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  • 1. Aalbers, J.
    et al.
    Agostini, F.
    Alfonsi, M.
    Amaro, F. D.
    Amsler, C.
    Aprile, E.
    Arazi, L.
    Arneodo, F.
    Barrow, P.
    Baudis, L.
    Benabderrahmane, M. L.
    Berger, T.
    Beskers, B.
    Breskin, A.
    Breur, P. A.
    Brown, A.
    Brown, E.
    Bruenner, S.
    Bruno, G.
    Budnik, R.
    Butikofer, L.
    Calvén, Jakob
    Stockholm University, Faculty of Science, Department of Physics.
    Cardoso, J. M. R.
    Cichon, D.
    Coderre, D.
    Colijn, A. P.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Cussonneau, J. P.
    Decowski, M. P.
    Diglio, S.
    Drexlin, G.
    Duchovni, E.
    Erdal, E.
    Eurin, G.
    Ferella, Alfredo
    Stockholm University, Faculty of Science, Department of Physics.
    Fieguth, A.
    Fulgione, W.
    Rosso, A. Gallo
    Di Gangi, P.
    Di Giovanni, A.
    Galloway, M.
    Garbini, M.
    Geis, C.
    Glueck, F.
    Grandi, L.
    Greene, Z.
    Grignon, C.
    Hasterok, C.
    Hannen, V.
    Hogenbirk, E.
    Howlett, J.
    Hilk, D.
    Hils, C.
    James, A.
    Kaminsky, B.
    Kazama, S.
    Kilminster, B.
    Kish, A.
    Krauss, L. M.
    Landsman, H.
    Lang, R. F.
    Lin, Q.
    Linde, F. L.
    Lindemann, S.
    Lindner, M.
    Lopes, J. A. M.
    Undagoitia, T. Marrodan
    Masbou, J.
    Massoli, F. V.
    Mayani, D.
    Messina, M.
    Micheneau, K.
    Molinario, A.
    Morå, Knut D.
    Stockholm University, Faculty of Science, Department of Physics.
    Morteau, E.
    Murra, M.
    Naganoma, J.
    Newstead, J. L.
    Ni, K.
    Oberlack, U.
    Pakarha, P.
    Pelssers, Bart
    Stockholm University, Faculty of Science, Department of Physics.
    de Perio, P.
    Persiani, R.
    Piastra, F.
    Piro, M. C.
    Plante, G.
    Rauch, L.
    Reichard, S.
    Rizzo, A.
    Rupp, N.
    Dos Santos, J. M. F.
    Sartorelli, G.
    Scheibelhut, M.
    Schindler, S.
    Schumann, M.
    Schreiner, J.
    Lavina, L. Scotto
    Selvi, M.
    Shagin, P.
    Silva, M. C.
    Simgen, H.
    Sissol, P.
    von Sivers, M.
    Thers, D.
    Thum, J.
    Tiseni, A.
    Trotta, R.
    Tunnell, C. D.
    Valerius, K.
    Vargas, M. A.
    Wang, H.
    Wei, Y.
    Weinheimer, C.
    Wester, T.
    Wulf, J.
    Zhang, Y.
    Zhu, T.
    Zuber, K.
    DARWIN: towards the ultimate dark matter detector2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 11, article id 017Article in journal (Refereed)
    Abstract [en]

    DARk matter WImp search with liquid xenoN (DARWIN(2)) will be an experiment for the direct detection of dark matter using a multi-ton liquid xenon time projection chamber at its core. Its primary goal will be to explore the experimentally accessible parameter space for Weakly Interacting Massive Particles (WIMPs) in a wide mass-range, until neutrino interactions with the target become an irreducible background. The prompt scintillation light and the charge signals induced by particle interactions in the xenon will be observed by VUV sensitive, ultra-low background photosensors. Besides its excellent sensitivity to WIMPs above a mass of 5 GeV/c(2), such a detector with its large mass, low-energy threshold and ultra-low background level will also be sensitive to other rare interactions. It will search for solar axions,galactic axion-like particles and the neutrinoless double-beta decay of Xe-136, as well as measure the low-energy solar neutrino flux with <1% precision, observe coherent neutrino-nucleus interactions, and detect galactic supernovae. We present the concept of the DARWIN detector and discuss its physics reach, the main sources of backgrounds and the ongoing detector design and R&D efforts.

  • 2. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Bloom, E. D.
    Bonino, R.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cuoco, Alessandro
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Italy; Universita degli Studi di Torino, Italy.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Ferrara, E. C.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Guiriec, S.
    Gustafsson, M.
    Hewitt, J. W.
    Hou, X.
    Kamae, T.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Malyshev, D.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Negro, M.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Sánchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 9, article id 008Article in journal (Refereed)
    Abstract [en]

    We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Telescope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predictions compared to previous work. More specifically, we estimate the cosmologically-induced gamma-ray intensity to have an uncertainty of a factor similar to 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former on the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies. This is possible thanks to the new Fermi LAT IGRB measurement, which now extends up to an energy of 820 GeV. We quantify uncertainties in detail and show the potential this type of search offers for testing the WIMP paradigm with a complementary and truly cosmological probe of DM particle signals.

  • 3. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bouvier, A.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    de Angelis, A.
    de Palma, F.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Dumora, D.
    Edmonds, Y.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Frailis, M.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Guiriec, S.
    Gustafsson, M.
    Harding, A. K.
    Hayashida, M.
    Horan, D.
    Hughes, R. E.
    Jeltema, T. E.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S. -H
    Garde, Maja Llena
    Stockholm University, Faculty of Science, Department of Physics.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Panetta, J. H.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Profumo, S.
    Raino, S.
    Razzano, M.
    Reposeur, T.
    Ritz, S.
    Rodriguez, A. Y.
    Roth, M.
    Sadrozinski, H. F. -W
    Sander, A.
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Usher, T. L.
    Vasileiou, V.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Ylinen, T.
    Ziegler, M.
    Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope2010In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 5, p. 25-Article in journal (Refereed)
    Abstract [en]

    Nearby clusters and groups of galaxies are potentially bright sources of highenergy gamma-ray emission resulting from the pair-annihilation of dark matter particles. However, no significant gamma-ray emission has been detected so far from clusters in the first 11 months of observations with the Fermi Large Area Telescope. We interpret this non-detection in terms of constraints on dark matter particle properties. In particular for leptonic annihilation final states and particle masses greater than similar to 200GeV, gamma-ray emission from inverse Compton scattering of CMB photons is expected to dominate the dark matter annihilation signal from clusters, and our gamma-ray limits exclude large regions of the parameter space that would give a good fit to the recent anomalous Pamela and Fermi-LAT electron-positron measurements. We also present constraints on the annihilation of more standard dark matter candidates, such as the lightest neutralino of supersymmetric models. The constraints are particularly strong when including the fact that clusters are known to contain substructure at least on galaxy scales, increasing the expected gammaray flux by a factor of similar to 5 over a smooth-halo assumption. We also explore the effect of uncertainties in cluster dark matter density profiles, finding a systematic uncertainty in the constraints of roughly a factor of two, but similar overall conclusions. In this work, we focus on deriving limits on dark matter models; a more general consideration of the Fermi-LAT data on clusters and clusters as gamma-ray sources is forthcoming.

  • 4. Ahnen, M. L.
    et al.
    Ansoldi, S.
    Antonelli, L. A.
    Antoranz, P.
    Babic, A.
    Banerjee, B.
    Bangale, P.
    Barres de Almeida, U.
    Barrio, J. A.
    Gonzalez, J. Becerra
    Bednarek, W.
    Bernardinik, E.
    Biasuzzi, B.
    Biland, A.
    Blanch, O.
    Bonnefoy, S.
    Bonnoli, G.
    Borracci, F.
    Bretz, T.
    Carmona, E.
    Carosi, A.
    Chatterjee, A.
    Clavero, R.
    Colin, P.
    Colombo, E.
    Contreras, J. L.
    Cortina, J.
    Covino, S.
    Da Vela, P.
    Dazzi, F.
    De Angelis, A.
    De Lotto, B.
    De Ona Wilhelmi, E.
    Delgado Mendez, C.
    Di Pierro, F.
    Dominis Prester, D.
    Dorner, D.
    Doro, M.
    Einecke, S.
    Eisenacher Glawion, D.
    Elsaesser, D.
    Fernandez-Barral, A.
    Fidalgo, D.
    Fonseca, M. V.
    Font, L.
    Frantzen, K.
    Fruck, C.
    Galindo, D.
    Garcia Lopez, R. J.
    Garczarczyk, M.
    Garrido Terrats, D.
    Gaug, M.
    Giammaria, P.
    Godinovic, N.
    Gonzalez Munoz, A.
    Guberman, D.
    Hahn, A.
    Hanabata, Y.
    Hayashida, M.
    Herrera, J.
    Hose, J.
    Hrupec, D.
    Hughes, G.
    Idec, W.
    Kodani, K.
    Konno, Y.
    Kubo, H.
    Kushida, J.
    La Barbera, A.
    Lelas, D.
    Lindfors, E.
    Lombardi, S.
    Longo, F.
    Lopez, M.
    Lopez-Coto, R.
    Lopez-Dramas, A.
    Lorenz, E.
    Majumdar, P.
    Makariev, M.
    Mallot, K.
    Maneva, G.
    Manganaro, M.
    Mannheim, K.
    Maraschi, L.
    Marcote, B.
    Mariotti, M.
    Martinez, M.
    Mazing, D.
    Menzel, U.
    Miranda, J. M.
    Mirzoyan, R.
    Moralejo, A.
    Moretti, E.
    Nakajima, D.
    Neustroev, V.
    Niedzwiecki, A.
    Nievas Rosillo, M.
    Nilsson, K.
    Nishijima, K.
    Noda, K.
    Orito, R.
    Overkemping, A.
    Paiano, S.
    Palacio, J.
    Palatiello, M.
    Paneque, D.
    Paoletti, R.
    Paredes, J. M.
    Paredes-Fortuny, X.
    Persic, M.
    Poutanen, J.
    Prada Moroni, P. G.
    Prandini, E.
    Puljak, I.
    Rhode, W.
    Ribo, M.
    Rico, J.
    Rodriguez Garcia, J.
    Saito, T.
    Satalecka, K.
    Schultz, C.
    Schweizer, T.
    Shore, S. N.
    Sillanpaa, A.
    Sitarek, J.
    Snidaric, I.
    Sobczynska, D.
    Stamerra, A.
    Steinbring, T.
    Strzys, M.
    Takalo, L.
    Takami, H.
    Tavecchio, F.
    Temnikov, P.
    Terzic, T.
    Tescaro, D.
    Teshimag, M.
    Thaele, J.
    Torres, D. F.
    Toyama, T.
    Treves, A.
    Verguilov, V.
    Vovk, I.
    Ward, J. E.
    Will, M.
    Wu, M. H.
    Zanins, R.
    Aleksic, J.
    Wood, M.
    Anderson, Brandon
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bloom, E. D.
    Cohen-Tanugi, J.
    Drlica-Wagner, A.
    Mazziotta, M. N.
    Sanchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Strigari, L.
    Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 2, article id 039Article in journal (Refereed)
    Abstract [en]

    We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. These limits improve on previously published Fermi-LAT and MAGIC results by up to a factor of two at certain masses. Our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors.

  • 5.
    Ahrens, Maryon
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Danninger, Matthias
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Dumm, Jonathan P.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Edsjö, Joakim
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Finley, Chad
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Flis, Samuel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hulth, Per Olof
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Hultqvist, Klas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Savage, Christopher
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Walck, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Wolf, Martin
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zoll, Marcel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Improved limits on dark matter annihilation in the Sun with the 79-string IceCube detector and implications for supersymmetry2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, article id 022Article in journal (Refereed)
    Abstract [en]

    We present an improved event-level likelihood formalism for including neutrino telescope data in global fits to new physics. We derive limits on spin-dependent dark matter-proton scattering by employing the new formalism in a re-analysis of data from the 79-string IceCube search for dark matter annihilation in the Sun, including explicit energy information for each event. The new analysis excludes a number of models in the weak-scale minimal supersymmetric standard model (MSSM) for the first time. This work is accompanied by the public release of the 79-string IceCube data, as well as an associated computer code for applying the new likelihood to arbitrary dark matter models.

  • 6.
    Ahrens, Maryon
    et al.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Bohm, Christian
    Stockholm University, Faculty of Science, Department of Physics.
    Dumm, Jonathan P.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Finley, Chad
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Flis, Samuel
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Hulth, Per Olof
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Hultqvist, Klas
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Walck, Christian
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Wolf, Martin
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Zoll, Marcel
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 1, article id 037Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.

  • 7. Ajello, M.
    et al.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Enoto, T.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Graham, P.
    Grenier, I. A.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashida, M.
    Hughes, R. E.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lionetto, A. M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Razzano, M.
    Ritz, S.
    Roth, M.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schalk, T. L.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Yang, Z.
    Zimmer, S.
    Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT2012In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 2, p. 012-Article in journal (Refereed)
    Abstract [en]

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to gamma gamma should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  • 8.
    Akrami, Yashar
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Savage, Christopher
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Scott, Pat
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Edsjö, Joakim
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    How well will ton-scale dark matter direct detection experiments constrain minimal supersymmetry?2011In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, p. 012-Article in journal (Refereed)
    Abstract [en]

    Weakly interacting massive particles (WIMPs) are amongst the most interesting dark matter (DM) candidates. Many DM candidates naturally arise in theories beyond the standard model (SM) of particle physics, like weak-scale supersymmetry (SUSY). Experiments aim to detect WIMPs by scattering, annihilation or direct production, and thereby determine the underlying theory to which they belong, along with its parameters. Here we examine the prospects for further constraining the Constrained Minimal Supersymmetric Standard Model (CMSSM) with future ton-scale direct detection experiments. We consider ton-scale extrapolations of three current experiments: CDMS, XENON and COUPP, with 1000 kg-years of raw exposure each. We assume energy resolutions, energy ranges and efficiencies similar to the current versions of the experiments, and include backgrounds at target levels. Our analysis is based on full likelihood constructions for the experiments. We also take into account present uncertainties on hadronic matrix elements for neutralino-quark couplings, and on halo model parameters. We generate synthetic data based on four benchmark points and scan over the CMSSM parameter space using nested sampling. We construct both Bayesian posterior PDFs and frequentist profile likelihoods for the model parameters, as well as the mass and various cross-sections of the lightest neutralino. Future ton-scale experiments will help substantially in constraining supersymmetry, especially when results of experiments primarily targeting spin-dependent nuclear scattering are combined with those directed more toward spin-independent interactions.

  • 9.
    Akrami, Yashar
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Savage, Christopher
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Scott, Pat
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Edsjö, Joakim
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Statistical coverage for supersymmetric parameter estimation: a case study with direct detection of dark matter2011In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, p. 002-Article in journal (Refereed)
    Abstract [en]

    Models of weak-scale supersymmetry offer viable dark matter (DM) candidates. Their parameter spaces are however rather large and complex, such that pinning down the actual parameter values from experimental data can depend strongly on the employed statistical framework and scanning algorithm. In frequentist parameter estimation, a central requirement for properly constructed confidence intervals is that they cover true parameter values, preferably at exactly the stated confidence level when experiments are repeated infinitely many times. Since most widely-used scanning techniques are optimised for Bayesian statistics, one needs to assess their abilities in providing correct confidence intervals in terms of the statistical coverage. Here we investigate this for the Constrained Minimal Supersymmetric Standard Model (CMSSM) when only constrained by data from direct searches for dark matter. We construct confidence intervals from one-dimensional profile likelihoods and study the coverage by generating several pseudo-experiments for two benchmark sets of pseudo-true parameters. We use nested sampling to scan the parameter space and evaluate the coverage for the two benchmarks when either flat or logarithmic priors are imposed on gaugino and scalar mass parameters. We observe both under- and over-coverage, which in some cases vary quite dramatically when benchmarks or priors are modified. We show how most of the variation can be explained as the impact of explicit and implicit priors, where the latter are indirectly imposed by physicality conditions. For comparison, we also evaluate the coverage for Bayesian credible intervals, and (predictably) observe significant under-coverage in those cases.

  • 10. Albornoz, N. L. González
    et al.
    Schmidt-May, Angnis
    von Strauss, Mikael
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Dark matter scenarios with multiple spin-2 fields2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 1, article id 014Article in journal (Refereed)
    Abstract [en]

    We study ghost-free multimetric theories for (N + 1) tensor fields with a coupling to matter and maximal global symmetry group S-N x (Z(2))(N). Their mass spectra contain a massless mode, the graviton, and N massive spin-2 modes. One of the massive modes is distinct by being the heaviest, the remaining (N - 1) massive modes are simply identical copies of each other. All relevant physics can therefore be understood from the case N = 2. Focussing on this case, we compute the full perturbative action up to cubic order and derive several features that hold to all orders in perturbation theory. The lighter massive mode does not couple to matter and neither of the massive modes decay into massless gravitons. We propose the lighter massive particle as a candidate for dark matter and investigate its phenomenology in the parameter region where the matter coupling is dominated by the massless graviton. The relic density of massive spin-2 can originate from a freeze-in mechanism or from gravitational particle production, giving rise to two different dark matter scenarios. The allowed parameter regions are very different from those in scenarios with only one massive spin-2 field and more accessible to experiments.

  • 11.
    Anderson, Brandon
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Wallenberg Academy Fellow, Sweden.
    Gustafsson, M.
    Sánchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Caputo, R.
    Search for Gamma-ray Lines Towards Galaxy Clusters with the Fermi-LAT2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 2, article id 026Article in journal (Refereed)
    Abstract [en]

    We report on a search for monochromatic gamma-ray features in the spectra of galaxy clusters observed by the Fermi Large Area Telescope. Galaxy clusters are the largest structures in the Universe that are bound by dark matter (DM), making them an important testing ground for possible self-interactions or decays of the DM particles. Monochromatic gamma-ray lines provide a unique signature due to the absence of astrophysical backgrounds and are as such considered a smoking-gun signature for new physics. An unbinned joint likelihood analysis of the sixteen most promising clusters using five years of data at energies between 10 and 400 GeV revealed no significant features. For the case of self-annihilation, we set upper limits on the monochromatic velocity-averaged interaction cross section. These limits are compatible with those obtained from observations of the Galactic Center, albeit weaker due to the larger distance to the studied clusters.

  • 12. Aprile, E.
    et al.
    Aalbers, J.
    Agostini, F.
    Alfonsi, M.
    Amaro, F. D.
    Anthony, M.
    Arazi, L.
    Arneodo, F.
    Balan, C.
    Barrow, P.
    Baudis, L.
    Bauermeister, Boris
    Stockholm University, Faculty of Science, Department of Physics. Johannes Gutenberg-Universität Mainz, Germany.
    Berger, T.
    Breur, P.
    Breskin, A.
    Brown, A.
    Brown, E.
    Bruenner, S.
    Bruno, G.
    Budnik, R.
    Butikofer, L.
    Cardoso, J. M. R.
    Cervantes, M.
    Cichon, D.
    Coderre, D.
    Colijn, A. P.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Contreras, H.
    Cussonneau, J. P.
    Decowski, M. P.
    de Perio, P.
    Di Gangi, P.
    Di Giovanni, A.
    Duchovni, E.
    Fattori, S.
    Ferella, Alfredo D.
    Stockholm University, Faculty of Science, Department of Physics. INFN-Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, Italy.
    Fieguth, A.
    Franco, D.
    Fulgione, W.
    Galloway, M.
    Garbini, M.
    Geis, C.
    Goetzke, L. W.
    Greene, Z.
    Grignon, C.
    Gross, E.
    Hampel, W.
    Hasterok, C.
    Itay, R.
    Kaether, F.
    Kaminsky, B.
    Kessler, G.
    Kish, A.
    Landsman, H.
    Lang, R. F.
    Lellouch, D.
    Levinson, L.
    Le Calloch, M.
    Levy, C.
    Lindemann, S.
    Lindner, M.
    Lopes, J. A. M.
    Lyashenko, A.
    Macmullin, S.
    Manfredini, A.
    Undagoitia, T. Marrodan
    Masbou, J.
    Massoli, F. V.
    Mayani, D.
    Fernandez, A. J. Melgarejo
    Meng, Y.
    Messina, M.
    Micheneau, K.
    Miguez, B.
    Molinario, A.
    Murra, M.
    Naganoma, J.
    Oberlack, U.
    Orrigo, S. E. A.
    Pakarha, P.
    Pelssers, Bart
    Stockholm University, Faculty of Science, Department of Physics.
    Persiani, R.
    Piastra, F.
    Pienaar, J.
    Plante, G.
    Priel, N.
    Rauch, L.
    Reichard, S.
    Reuter, C.
    Rizzo, A.
    Rosendahl, S.
    Rupp, N.
    dos Santos, J. M. F.
    Sartorelli, G.
    Scheibelhut, M.
    Schindler, S.
    Schreiner, J.
    Schumann, M.
    Lavina, L. Scotto
    Selvi, M.
    Shagin, P.
    Simgen, H.
    Stein, A.
    Thers, D.
    Tiseni, A.
    Trinchero, G.
    Tunnell, C.
    von Sivers, M.
    Wall, R.
    Wang, H.
    Weber, M.
    Wei, Y.
    Weinheimer, C.
    Wulf, J.
    Zhang, Y.
    Physics reach of the XENON1T dark matter experiment2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, article id 027Article in journal (Refereed)
    Abstract [en]

    The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds. The total electronic recoil background in 1 tonne fiducial volume and (1, 12) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is (1.80+/-0.15) . 10(-4) (kg.day.keV)(-1), mainly due to the decay of Rn-222 daughters inside the xenon target. The nuclear recoil background in the corresponding nuclear recoil equivalent energy region (4, 50) keV, is composed of (0.6 +/- 0.1) (t.y)(-1) from radiogenic neutrons, (1.8+/-0.3) . 10(-2) (t.y)(-1) from coherent scattering of neutrinos, and less than 0.01 (t.y)(-1) from muon-induced neutrons. The sensitivity of XENON1T is calculated with the Pro file Likelihood Ratio method, after converting the deposited energy of electronic and nuclear recoils into the scintillation and ionization signals seen in the detector. We take into account the systematic uncertainties on the photon and electron emission model, and on the estimation of the backgrounds, treated as nuisance parameters. The main contribution comes from the relative scintillation efficiency L-eff, which affects both the signal from WIMPs and the nuclear recoil backgrounds. After a 2 y measurement in 1 tonne fiducial volume, the sensitivity reaches a minimum cross section of 1.6 . 10(-47) cm(2) at m(chi) = 50 GeV/c(2).

  • 13. Aprile, E.
    et al.
    Aalbers, J.
    Agostini, F.
    Alfonsi, M.
    Amaro, F. D.
    Anthony, M.
    Arneodo, F.
    Barrow, P.
    Baudis, L.
    Bauermeister, Boris
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Benabderrahmane, M. L.
    Berger, T.
    Breur, P. A.
    Brown, A.
    Brown, E.
    Bruenner, S.
    Bruno, G.
    Budnik, R.
    Buetikofer, L.
    Calvén, Jakob
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cardoso, J. M. R.
    Cervantes, M.
    Cichon, D.
    Coderre, D.
    Colijn, A. P.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cussonneau, J. P.
    Decowski, M. P.
    de Perio, P.
    Di Gangi, P.
    Di Giovanni, A.
    Diglio, S.
    Eurin, G.
    Fei, J.
    Ferella, Alfredo D.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Fieguth, A.
    Franco, D.
    Fulgione, W.
    Rosso, A. Gallo
    Galloway, M.
    Gao, F.
    Garbini, M.
    Geis, C.
    Goetzke, L. W.
    Greene, Z.
    Grignon, C.
    Hasterok, C.
    Hogenbirk, E.
    Itay, R.
    Kaminsky, B.
    Kessler, G.
    Kish, A.
    Landsman, H.
    Lang, R. F.
    Lellouch, D.
    Levinson, L.
    Lin, Q.
    Lindemann, S.
    Lindner, M.
    Lombardi, F.
    Lopes, J. A. M.
    Manfredini, A.
    Maris, I.
    Undagoitia, T. Marrodan
    Masbou, J.
    Massoli, F. V.
    Masson, D.
    Mayani, D.
    Messina, M.
    Micheneau, K.
    Molinario, A.
    Murra, M.
    Naganoma, J.
    Ni, K.
    Oberlack, U.
    Pakarha, P.
    Pelssers, Bart
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Persiani, R.
    Piastra, F.
    Pienaar, J.
    Pizzella, V.
    Piro, M. -C.
    Plante, G.
    Priel, N.
    Rauch, L.
    Reichard, S.
    Reuter, C.
    Rizzo, A.
    Rosendahl, S.
    Rupp, N.
    dos Santos, J. M. F.
    Sartorelli, G.
    Scheibelhut, M.
    Schindler, S.
    Schreiner, J.
    Schumann, M.
    Lavina, L. Scotto
    Selvi, M.
    Shagin, P.
    Silva, M.
    Simgen, H.
    von Sivers, M.
    Stein, A.
    Thers, D.
    Tiseni, A.
    Trinchero, G.
    Tunnell, C.
    Vargas, M.
    Wang, H.
    Wei, Y.
    Weinheimer, C.
    Wulf, J.
    Ye, J.
    Zhang, Y.
    Search for magnetic inelastic dark matter with XENON1002017In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 10, article id 039Article in journal (Refereed)
    Abstract [en]

    We present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II. This very distinct signature is predicted in the framework of magnetic inelastic dark matter which has been proposed to reconcile the modulation signal reported by the DAMA/LIBRA collaboration with the null results from other direct detection experiments. No candidate event has been found in the region of interest and upper limits on the WIMP's magnetic dipole moment are derived. The scenarios proposed to explain the DAMA/LIBRA modulation signal by magnetic inelastic dark matter interactions of WIMPs with masses of 58.0 GeV/c(2) and 122.7 GeV/c(2) are excluded at 3.3 sigma and 9.3 sigma, respectively.

  • 14. Ashoorioon, Amjad
    et al.
    Casadio, Roberto
    Koivisto, Tomi
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Anisotropic non-gaussianity from rotational symmetry breaking excited initial states2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, article id 002Article in journal (Refereed)
    Abstract [en]

    If the initial quantum state of the primordial perturbations broke rotational invariance, that would be seen as a statistical anisotropy in the angular correlations of the cosmic microwave background radiation (CMBR) temperature fluctuations. This can be described by a general parameterisation of the initial conditions that takes into account the possible direction-dependence of both the amplitude and the phase of particle creation during inflation. The leading effect in the CMBR two-point function is typically a quadrupole modulation, whose coefficient is analytically constrained here to be vertical bar B vertical bar less than or similar to 0.06. The CMBR three-point function then acquires enhanced non-gaussianity, especially for the local con figurations. In the large occupation number limit, a distinctive prediction is a modulation of the non-gaussianity around a mean value depending on the angle that short and long wavelength modes make with the preferred direction. The maximal variations with respect to the mean value occur for the con figurations which are coplanar with the preferred direction and the amplitude of the non-gaussianity increases (decreases) for the short wavelength modes aligned with (perpendicular to) the preferred direction. For a high scale model of inflation with maximally pumped up isotropic occupation and epsilon similar or equal to 0. 01 the difference between these two configurations is about 0. 27, which could be detectable in the future. For purely anisotropic particle creation, the non-Gaussianity can be larger and its anisotropic feature very sharp. The non-gaussianity can then reach f(NL)similar to 30 in the preferred direction while disappearing from the correlations in the orthogonal plane.

  • 15.
    Baltz, Edward A.
    et al.
    Stanford, USA.
    Bergström, Lars
    Stockholm University, Faculty of Science, Department of Physics.
    Bringmann, Torsten
    Stockholm University, Faculty of Science, Department of Physics.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Edsjö, Joakim
    Stockholm University, Faculty of Science, Department of Physics.
    Sellerholm, Alexander
    Stockholm University, Faculty of Science, Department of Physics.
    Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals2008In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 0807, no 013Article in journal (Refereed)
    Abstract [en]

    We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) for indirectly detecting weakly interacting massive particles (WIMPs) through the γ-ray signal that their pair annihilation produces. WIMPs are among the favorite candidates for explaining the compelling evidence that about 80% of the mass in the Universe is non-baryonic dark matter (DM). They are serendipitously motivated by various extensions of the standard model of particle physics such as supersymmetry and universal extra dimensions (UED). With its unprecedented sensitivity and its very large energy range (20 MeV to more than 300 GeV) the main instrument on board the GLAST satellite, the Large Area Telescope (LAT), will open a new window of discovery. As our estimates show, the LAT will be able to detect an indirect DM signature for a large class of WIMP models given a cuspy profile for the DM distribution. Using the current state of the art Monte Carlo and event reconstruction software developed within the LAT collaboration, we present preliminary sensitivity studies for several possible sources inside and outside the Galaxy. We also discuss the potential of the LAT to detect UED via the electron/positron channel. Diffuse background modeling and other background issues that will be important in setting limits or seeing a signal are presented

  • 16. Beltran Jimenez, Jose
    et al.
    Heisenberg, Lavinia
    Koivisto, Tomi S.
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Helsinki Institute of Physics, Finland; Helsinki University, Finland.
    Teleparallel Palatini theories2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, article id 039Article in journal (Refereed)
    Abstract [en]

    The Palatini formalism, which assumes the metric and the affine connection as independent variables, is developed for gravitational theories in flat geometries. We focus on two particularly interesting scenarios. First, we fix the connection to be metric compatible, as done in the usual teleparallel theories, but we follow a completely covariant approach by imposing the constraints with suitable Lagrange multipliers. For a general quadratic theory we show how torsion naturally propagates and we reproduce the Teleparallel Equivalent of General Relativity as a particular quadratic action that features an additional Lorentz symmetry. We then study the much less explored theories formulated in a geometry with neither curvature nor torsion, so that all the geometrical information is encoded in the non-metricity. We discuss how this geometrical framework leads to a purely inertial connection that can thus be completely removed by a coordinate gauge choice, the coincident gauge. From the quadratic theory we recover a simpler formulation of General Relativity in the form of the Einstein action, which enjoys an enhanced symmetry that reduces to a second linearised diffeomorphism at linear order. More general theories in both geometries can be formulated consistently by taking into account the inertial connection and the associated additional degrees of freedom. As immediate applications, the new cosmological equations and their Newtonian limit are considered, where the role of the lapse in the consistency of the equations is clarified, and the Schwarzschild black hole entropy is computed by evaluating the corresponding Euclidean action. We discuss how the boundary terms in the usual formulation of General Relativity are related to different choices of coordinates in its coincident version and show that in isotropic coordinates the Euclidean action is finite without the need to introduce boundary or normalisation terms. Finally, we discuss the double-copy structure of the gravity amplitudes and the bootstrapping of gravity within the framework of coincident General Relativity.

  • 17.
    Berg, Marcus
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Karlstad University, Sweden.
    Buchberger, Igor
    Enander, Jonas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mörtsell, Edvard
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sjörs, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Growth histories in bimetric massive gravity2012In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, article id 021Article in journal (Refereed)
    Abstract [en]

    We perform cosmological perturbation theory in Hassan-Rosen bimetric gravity for general homogeneous and isotropic backgrounds. In the de Sitter approximation, we obtain decoupled sets of massless and massive scalar gravitational fluctuations. Matter perturbations then evolve like in Einstein gravity. We perturb the future de Sitter regime by the ratio of matter to dark energy, producing quasi-de Sitter space. In this more general setting the massive and massless fluctuations mix. We argue that in the quasi-de Sitter regime, the growth of structure in bimetric gravity differs from that of Einstein gravity.

  • 18.
    Berg, Marcus
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Edsjö, Joakim
    Stockholm University, Faculty of Science, Department of Physics.
    Gondolo, Paolo
    University of Utah.
    Lundström, Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Sjörs, Stefan
    Stockholm University, Faculty of Science, Department of Physics.
    Neutralino Dark Matter in BMSSM Effective Theory2009In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 08Article in journal (Refereed)
    Abstract [en]

    We study thermal neutralino dark matter in an effective field theory extension of the MSSM, called ``Beyond the MSSM'' (BMSSM) in Dine, Seiberg and Thomas (2007). In this class of effective field theories, the field content of the MSSM is unchanged, but the little hierarchy problem is alleviated by allowing small corrections to the Higgs/higgsino part of the Lagrangian. We perform parameter scans and compute the dark matter relic density. The light higgsino LSP scenario is modified the most; we find new regions of parameter space compared to the standard MSSM. This involves interesting interplay between the WMAP dark matter bounds and the LEP chargino bound. We also find some changes for gaugino LSPs, partly due to annihilation through a Higgs resonance, and partly due to coannihilation with light top squarks in models that are ruled in by the new effective terms.

  • 19.
    Bergström, Lars
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bertone, Gianfranco
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Farnier, Christian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Weniger, Christoph
    Investigating gamma ray lines from dark matter with future observatories2012In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 11, p. 025-Article in journal (Refereed)
    Abstract [en]

    We study the prospects for studying line features in gamma-ray spectra with upcoming gamma-ray experiments, such as HESS-II, the Cherenkov Telescope Array (CTA), and the GAMMA-400 satellite. As an example we use the narrow feature at 130 GeV seen in public data from the Fermi-LAT satellite. We found that all three experiments should be able to confidently confirm or rule out the presence of this 130 GeV feature. If it is real, it should be confirmed with a confidence level higher than 5 sigma. Assuming it to be a spectral signature of dark matter origin, GAMMA-400, thanks to a projected energy resolution of about 1.5 % at 100 GeV, should also be able to resolve both the gamma gamma line and a corresponding Z gamma or H gamma feature, if the corresponding branching ratio is comparable to that into two photons. It will also allow to distinguish between a gamma-ray line and the similar feature resulting from internal bremsstrahlung photons.

  • 20. Blanchet, Luc
    et al.
    Heisenberg, Lavinia
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Dipolar dark matter with massive bigravity2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, article id 026Article in journal (Refereed)
    Abstract [en]

    Massive gravity theories have been developed as viable IR, modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because of the particular couplings of the matter fields and vector field to the metrics, a ghost in the decoupling limit is present in the dark matter sector. However, it might be possible to push the mass of the ghost beyond the strong coupling scale by an appropriate choice of the parameters of the model. Crucial questions to address in future work are the exact mass of the ghost, and the cosmological implications of the model.

  • 21. Blennow, Mattias
    et al.
    Edsjoe, Joakim
    Stockholm University, Faculty of Science, Department of Physics.
    Ohlsson, Tommy
    Neutrinos from WIMP annihilations obtained using a full three-flavor Monte Carlo approach2008In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 1, p. 21-Article in journal (Refereed)
    Abstract [en]

    Weakly interacting massive particles (WIMPs) are one of the main candidates for making up the dark matter in the Universe. If these particles make up the dark matter, then they can be captured by the Sun or the Earth, sink to the respective cores, annihilate, and produce neutrinos. Thus, these neutrinos can be a striking dark matter signature at neutrino telescopes looking towards the Sun and/or the Earth. Here, we improve previous analyses on computing the neutrino yields from WIMP annihilations in several respects. We include neutrino oscillations in a full three-flavor framework as well as all effects from neutrino interactions on the way through the Sun (absorption, energy loss, and regeneration from tau decays). In addition, we study the effects of non-zero values of the mixing angle theta(13) as well as the normal and inverted neutrino mass hierarchies. Our study is performed in an event-based setting which makes these results very useful both for theoretical analyses and for building a neutrino telescope Monte Carlo code. All our results for the neutrino yields, as well as our Monte Carlo code, are publicly available. We find that the yield of muontype neutrinos from WIMP annihilations in the Sun is enhanced or suppressed, depending on the dominant WIMP annihilation channel. This effect is due to an effective favor mixing caused by neutrino oscillations. For WIMP annihilations inside the Earth, the distance from source to detector is too small to allow for any significant amount of oscillations at the neutrino energies relevant for neutrino telescopes.

  • 22. Blennow, Mattias
    et al.
    Herrero-Garcia, Juan
    Schwetz, Thomas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    A halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 5, article id 036Article in journal (Refereed)
    Abstract [en]

    We show that a positive signal in a dark matter (DM) direct detection experiment can be used to place a lower bound on the DM capture rate in the Sun, independent of the DM halo. For a given particle physics model and DM mass we obtain a lower bound on the capture rate independent of the local DM density, velocity distribution, galactic escape velocity, as well as the scattering cross section. We illustrate this lower bound on the capture rate by assuming that upcoming direct detection experiments will soon obtain a significant signal. When comparing the lower bound on the capture rate with limits on the high-energy neutrino flux from the Sun from neutrino telescopes, we can place upper limits on the branching fraction of DM annihilation channels leading to neutrinos. With current data from IceCube and Super-Kamiokande non-trivial limits can be obtained for spin-dependent interactions and direct annihilations into neutrinos. In some cases also annihilations into tau tau or bb start getting constrained. For spin-independent interactions current constraints are weak, but they may become interesting for data from future neutrino telescopes.

  • 23. Blennow, Mattias
    et al.
    Herrero-Garcia, Juan
    Schwetz, Thomas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Vogl, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Halo-independent tests of dark matter direct detection signals: local DM density, LHC, and thermal freeze-out2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, article id 039Article in journal (Refereed)
    Abstract [en]

    From an assumed signal in a Dark Matter (DM) direct detection experiment a lower bound on the product of the DM-nucleon scattering cross section and the local DM density is derived, which is independent of the local DM velocity distribution. This can be combined with astrophysical determinations of the local DM density. Within a given particle physics model the bound also allows a robust comparison of a direct detection signal with limits from the LHC. Furthermore, the bound can be used to formulate a condition which has to be fulfilled if the particle responsible for the direct detection signal is a thermal relic, regardless of whether it constitutes all DM or only part of it. We illustrate the arguments by adopting a simplified DM model with a Z' mediator and assuming a signal in a future xenon direct detection experiment.

  • 24.
    Blomqvist, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Enander, Jonas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mörtsell, Edvard
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Constraining dark energy fluctuations with supernova correlations2010In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 10, p. 018-Article in journal (Refereed)
    Abstract [en]

    We investigate constraints on dark energy fluctuations using type Ia supernovae. If dark energy is not in the form of a cosmological constant, that is if the equation of state is not equal to -1, we expect not only temporal, but also spatial variations in the energy density. Such fluctuations would cause local variations in the universal expansion rate and directional dependences in the redshift-distance relation. We present a scheme for relating a power spectrum of dark energy fluctuations to an angular covariance function of standard candle magnitude fluctuations. The predictions for a phenomenological model of dark energy fluctuations are compared to observational data in the form of the measured angular covariance of Hubble diagram magnitude residuals for type Ia supernovae in the Union2 compilation. The observational result is consistent with zero dark energy fluctuations. However, due to the limitations in statistics, current data still allow for quite general dark energy fluctuations as long as they are in the linear regime.

  • 25.
    Blomqvist, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mörtsell, Edvard
    Stockholm University, Faculty of Science, Department of Physics.
    Supernovae as seen by off-center observers in a local void2010In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 05, p. 006-Article in journal (Refereed)
    Abstract [en]

    Inhomogeneous universe models have been proposed as an alternative explanation for the apparent acceleration of the cosmic expansion that does not require dark energy. In the simplest class of inhomogeneous models, we live within a large, spherically symmetric void. Several studies have shown that such a model can be made consistent with many observations, in particular the redshift-luminosity distance relation for type Ia supernovae, provided that the void is of Gpc size and that we live close to the center. Such a scenario challenges the Copernican principle that we do not occupy a special place in the universe. We use the first-year Sloan Digital Sky Survey-II supernova search data set as well as the Constitution supernova data set to put constraints on the observer position in void models, using the fact that off-center observers will observe an anisotropic universe. We first show that a spherically symmetric void can give good fits to the supernova data for an on-center observer, but that the two data sets prefer very different voids. We then continue to show that the observer can be displaced at least fifteen percent of the void scale radius from the center and still give an acceptable fit to the supernova data. When combined with the observed dipole anisotropy of the cosmic microwave background however, we find that the data compells the observer to be located within about one percent of the void scale radius. Based on these results, we conclude that considerable fine-tuning of our position within the void is needed tofit the supernova data, strongly disfavouring the model from a Copernican principle point of view.

  • 26.
    Blomqvist, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Mörtsell, Edvard
    Stockholm University, Faculty of Science, Department of Physics.
    Noboli, Serena
    Stockholm University, Faculty of Science, Department of Physics.
    Probing dark energy inhomogeneities with supernovae2008In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 06, p. 027-Article in journal (Refereed)
    Abstract [en]

    We discuss the possibility of identifying anisotropic and/or inhomogeneous cosmological models using type Ia supernova data. A search for correlations in current type Ia peak magnitudes over a large range of angular scales yields a null result. However, the same analysis limited to supernovae at low redshift shows a feeble anticorrelation at the 2σ level at angular scales θ≈40°. Upcoming data from, e.g., the SNLS (Supernova Legacy Survey) and the SDSS-II (SDSS: Sloan Digital Sky Survey) supernova searches will improve our limits on the size of—or possibly detect—possible correlations also at high redshift at the per cent level in the near future. With data from the proposed SNAP (SuperNova Acceleration Probe) satellite, we will be able to detect the induced correlations from gravitational lensing on type Ia peak magnitudes on scales less than a degree.

  • 27. Boucenna, Sofiane M.
    et al.
    Kühnel, Florian
    Ohlsson, Tommy
    Visinelli, Luca
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Novel constraints on mixed dark-matter scenarios of primordial black holes and WIMPs2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 003Article in journal (Refereed)
    Abstract [en]

    We derive constraints on mixed dark-matter scenarios consisting of primordial black holes (PBHs) and weakly interacting massive particles (WIMPs). In these scenarios, we expect a density spike of the WIMPs that are gravitationally bound to the PBHs, which results in an enhanced annihilation rate and increased indirect detection prospects. We show that such scenarios provide strong constraints on the allowed fraction of PBHs that constitutes the dark matter, depending on the WIMP mass m(x) and the velocity-averaged annihilation cross-section <sigma v >. For the standard scenario with m(x) = 100 GeV and <sigma v > = 3 x 10(-26) cm(3)/s, we derive bounds that are stronger than all existing bounds for PBHs with masses 10(-12) M-circle dot less than or similar to M-BH less than or similar to 10(4) where M-circle dot, is the solar mass, and mostly so by several orders of magnitude.

  • 28. Boulanger, Francois
    et al.
    Ensslin, Torsten
    Fletcher, Andrew
    Girichides, Philipp
    Hackstein, Stefan
    Haverkorn, Marijke
    Horandel, Jorg R.
    Jaffe, Tess
    Jasche, Jens
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Kachelriess, Michael
    Kotera, Kumiko
    Pfrommer, Christoph
    Rachen, Jorg P.
    Rodrigues, Luiz F. S.
    Ruiz-Granados, Beatriz
    Seta, Amit
    Shukurov, Anvar
    Sigl, Guenter
    Steininger, Theo
    Vacca, Valentina
    van der Velden, Ellert
    van Vliet, Arjen
    Wang, Jiaxin
    IMAGINE: a comprehensive view of the interstellar medium, Galactic magnetic fields and cosmic rays2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, article id 049Article in journal (Refereed)
    Abstract [en]

    In this white paper we introduce the IMAGINE Consortium and its scientific background, goals and structure. The purpose of the consortium is to coordinate and facilitate the efforts of a diverse group of researchers in the broad areas of the interstellar medium, Galactic magnetic fields and cosmic rays, and our overarching goal is to develop more comprehensive insights into the structures and roles of interstellar magnetic fields and their interactions with cosmic rays within the context of Galactic astrophysics. The ongoing rapid development of observational and numerical facilities and techniques has resulted in a widely felt need to advance this subject to a qualitatively higher level of self-consistency, depth and rigour. This can only be achieved by the coordinated efforts of experts in diverse areas of astrophysics involved in observational, theoretical and numerical work. We present our view of the present status of this research area, identify its key unsolved problems and suggest a strategy that will underpin our work. The backbone of the consortium is the Interstellar MAGnetic field INference Engine, a publicly available Bayesian platform that employs robust statistical methods to explore the multi-dimensional likelihood space using any number of modular inputs. This tool will be used by the IMAGINE Consortium to develop an interpretation and modelling framework that provides the method, power and flexibility to interfuse information from a variety of observational, theoretical and numerical lines of evidence into a self-consistent and comprehensive picture of the thermal and non-thermal interstellar media. An important innovation is that a consistent understanding of the phenomena that are directly or indirectly influenced by the Galactic magnetic field, such as the deflection of ultra-high energy cosmic rays or extragalactic backgrounds, is made an integral part of the modelling. The IMAGINE Consortium, which is informal by nature and open to new participants, hereby presents a methodological framework for the modelling and understanding of Galactic magnetic fields that is available to all communities whose research relies on a state of the art solution to this problem.

  • 29. Bozorgnia, Nassim
    et al.
    Catena, Riccardo
    Schwetz, Thomas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Max Planck Society, Germany.
    Anisotropic dark matter distribution functions and impact on WIMP direct detection2013In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, p. 050-Article in journal (Refereed)
    Abstract [en]

    Dark matter N-body simulations suggest that the velocity distribution of dark matter is anisotropic. In this work we employ a mass model for the Milky Way whose parameters are determined from a fit to kinematical data. Then we adopt an ansatz for the dark matter phase space distribution which allows to construct self-consistent halo models which feature a degree of anisotropy as a function of the radius such as suggested by the simulations. The resulting velocity distributions are then used for an analysis of current data from dark matter direct detection experiments. We find that velocity distributions which are radially biased at large galactocentric distances (up to the virial radius) lead to an increased high velocity tail of the local dark matter distribution. This affects the interpretation of data from direct detection experiments, especially for dark matter masses around 10 GeV, since in this region the high velocity tail is sampled. We find that the allowed regions in the dark matter mass-cross section plane as indicated by possible hints for a dark matter signal reported by several experiments as well as conflicting exclusion limits from other experiments shift in a similar way when the halo model is varied. Hence, it is not possible to improve the consistency of the data by referring to anisotropic halo models of the type considered in this work.

  • 30. Bozorgnia, Nassim
    et al.
    Gelmini, Graciela B.
    Gondolo, Paolo
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). University of Utah, U.S.A..
    Ring-like features in directional dark matter detection2012In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 6, article id 037Article in journal (Refereed)
    Abstract [en]

    We discuss a novel dark matter signature relevant for directional detection of Weakly Interacting Massive Particles (WIMPs). For heavy enough WIMPs and low enough recoil energies, the maximum of the recoil rate is not in the direction of the average WIMP arrival direction but in a ring around it at an angular radius that increases with the WIMP mass and can approach 90 degrees at very low energies. The ring is easier to detect for smaller WIMP velocity dispersion and larger average WIMP velocities relative to the detector. In principle the ring could be used as an additional indication of the WIMP mass range.

  • 31. Bozorgnia, Nassim
    et al.
    Schwetz, Thomas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Is the effect of the Sun's gravitational potential on dark matter particles observable?2014In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, p. 013-Article in journal (Refereed)
    Abstract [en]

    We consider the effect of the Sun's gravitational potential on the local phase space distribution of dark matter particles, focusing on its implication for the annual modulation signal in direct detection experiments. We perform a fit to the modulation signal observed in DAMA/LIBRA and show that the allowed region shrinks if Solar gravitational focusing (GF) is included compared to the one without GF. Furthermore, we consider a possible signal in a generic future direct detection experiment, irrespective of the DAMA/LIBRA signal. Even for scattering cross sections close to the current bound and a large exposure of a xenon target with 270 ton yr it will be hard to establish the presence of GF from data. In the region of dark matter masses below 40 GeV an annual modulation signal can be established for our assumed experimental setup, however GF is negligible for low masses. In the high mass region, where GF is more important, the significance of annual modulation itself is very low. We obtain similar results for lighter targets such as Ge and Ar. We comment also on inelastic scattering, noting that GF becomes somewhat more important for exothermic scattering compared to the elastic case.

  • 32. Bozorgnia, Nassim
    et al.
    Schwetz, Thomas
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    What is the probability that direct detection experiments have observed dark matter?2014In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, p. 015-Article in journal (Refereed)
    Abstract [en]

    In Dark Matter direct detection we are facing the situation of some experiments reporting positive signals which are in conflict with limits from other experiments. Such conclusions are subject to large uncertainties introduced by the poorly known local Dark Matter distribution. We present a method to calculate an upper bound on the joint probability of obtaining the outcome of two potentially conflicting experiments under the assumption that the Dark Matter hypothesis is correct, but completely independent of assumptions about the Dark Matter distribution. In this way we can quantify the compatibility of two experiments in an astrophysics independent way. We illustrate our method by testing the compatibility of the hints reported by DAMA and CDMS-Si with the limits from the LUX and SuperCDMS experiments. The method does not require Monte Carlo simulations but is mostly based on using Poisson statistics. In order to deal with signals of few events we introduce the so-called signal length to take into account energy information. The signal length method provides a simple way to calculate the probability to obtain a given experimental outcome under a specified Dark Matter and background hypothesis.

  • 33.
    Brandenburg, Axel
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Colorado, U.S.A; Carnegie Mellon University, U.S.A..
    Durrer, Ruth
    Kahniashvili, Tina
    Mandalc, Sayan
    Yin, Weichen Winston
    Statistical properties of scale-invariant helical magnetic fields and applications to cosmology2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, article id 034Article in journal (Refereed)
    Abstract [en]

    We investigate the statistical properties of isotropic, stochastic, Gaussian distributed, helical magnetic fields characterized by different shapes of the energy spectra at large length scales and study the associated realizability condition. We discuss smoothed magnetic fields that are commonly used when the primordial magnetic field is constrained by observational data. We are particularly interested in scale-invariant magnetic fields that can be generated during the inflationary stage by quantum fluctuations. We determine the correlation length of such magnetic fields and relate it to the infrared cutoff of perturbations produced during inflation. We show that this scale determines the observational signatures of the inflationary magnetic fields on the cosmic microwave background. At smaller scales, the scale-invariant spectrum changes with time. It becomes a steeper weak-turbulence spectrum at progressively larger scales. We show numerically that the critical length scale where this happens is the turbulent-diffusive scale, which increases with the square root of time.

  • 34.
    Bringmann, Torsten
    Stockholm University, Faculty of Science, Department of Physics.
    High-energetic Cosmic Antiprotons from Kaluza-Klein Dark Matter2005In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 2005, no 08Article in journal (Refereed)
    Abstract [en]

    The lightest Kaluza–Klein particle (LKP) in models with universal extra dimensions is an interesting dark matter candidate that has recently received great attention. Here, we investigate the antiproton flux from LKP annihilations in the galactic halo. In our analysis we include different halo density profiles and allow for part of the dark matter to be concentrated in 'clumps' rather than being distributed homogeneously. After re-analysing the observational bounds on the allowed amount of clumpiness, we find that LKP annihilations may well give a significant contribution to the antiproton flux at energies higher than about 10 GeV, while for energies above around 500 GeV the conventional background is expected to dominate again. The shortly upcoming PAMELA satellite will already be able to measure part of this high-energy window, while planned experiments like AMS-02 will have access to the full energy range of interest.

  • 35.
    Bringmann, Torsten
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Doro, Michele
    Padova Univ.
    Fornasa, Mattia
    IAP, Paris.
    Dark Matter signals from Draco and Willman 1: Prospects for MAGIC II and CTA2009In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 01, no 016Article in journal (Refereed)
    Abstract [en]

    The next generation of ground-based Imaging Air Cherenkov Telescopes (IACTs) will play an important role in indirect dark matter searches. In this article, we consider two particularly promising candidate sources for dark matter annihilation signals, the nearby dwarf galaxies Draco and Willman 1, and study the prospects of detecting such a signal for the soon-operating MAGIC II telescope system as well as for the planned installation of CTA, taking special care of describing the experimental features that affect the detectional prospects. For the first time in such a study, we fully take into account the effect of internal bremsstrahlung, which has recently been shown to considerably enhance, in some cases, the gamma-ray flux at the high energies where Atmospheric Cherenkov Telescopes operate, thus leading to significantly harder annihilation spectra than traditionally considered. While the detection of the spectral features introduced by internal bremsstrahlung would constitute a smoking gun signature for dark matter annihilation, we find that for most models the overall flux still remains at a level that will be challenging to detect unless one adopts rather (though by no means overly) optimistic astrophysical assumptions about the distribution of dark matter in the dwarfs

  • 36. Bringmann, Torsten
    et al.
    Edsjö, Joakim
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gondolo, Paolo
    Ullio, Piero
    Bergström, Lars
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    DarkSUSY 6: an advanced tool to compute dark matter properties numerically2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 033Article in journal (Refereed)
    Abstract [en]

    The nature of dark matter remains one of the key science questions. Weakly Interacting Massive Particles (WIMPs) are among the best motivated particle physics candidates, allowing to explain the measured dark matter density by employing standard big-bang thermodynamics. Examples include the lightest supersymmetric particle, though many alternative particles have been suggested as a solution to the dark matter puzzle. We introduce here a radically new version of the widely used DarkSUSY package, which allows to compute the properties of such dark matter particles numerically. With DarkSUSY 6 one can accurately predict a large variety of astrophysical signals from dark matter, such as direct detection rates in low-background counting experiments and indirect detection signals through antiprotons, antideuterons, gamma rays and positrons from the Galactic halo, or high-energy neutrinos from the center of the Earth or of the Sun. For thermally produced dark matter like WIMPs, high-precision tools are provided for the computation of the relic density in the Universe today, as well as for the size of the smallest dark matter protohalos. Furthermore, the code allows to calculate dark matter self-interaction rates, which may affect the distribution of dark matter at small cosmological scales. Compared to earlier versions, DarkSUSY 6 introduces many significant physics improvements and extensions. The most fundamental new feature of this release, however, is that the code has been completely reorganized and brought into a highly modular and flexible shape. Switching between different pre-implemented dark matter candidates has thus become straight-forward, just as adding new - WIMP or non-WIMP - particle models or replacing any given functionality in a fully user-specified way. In this article, we describe the physics behind the computer package, along with the main structure and philosophy of this major revision of DarkSUSY. A detailed manual is provided together with the public release at www.darksusy.org.

  • 37. Burigana, C.
    et al.
    Carvalho, C. S.
    Trombetti, T.
    Notari, A.
    Quartin, M.
    Gasperis, G. D.
    Buzzelli, A.
    Vittorio, N.
    De Zotti, G.
    de Bernardis, P.
    Chluba, J.
    Bilicki, M.
    Danese, L.
    Delabrouille, J.
    Toffolatti, L.
    Lapi, A.
    Negrello, M.
    Mazzotta, P.
    Scott, D.
    Contreras, D.
    Achucarro, A.
    Ade, P.
    Allison, R.
    Ashdown, M.
    Ballardini, M.
    Banday, A. J.
    Banerji, R.
    Bartlett, J.
    Bartolo, N.
    Basak, S.
    Bersanelli, M.
    Bonaldi, A.
    Bonato, M.
    Borrill, J.
    Bouchet, F.
    Boulanger, F.
    Brinckmann, T.
    Bucher, M.
    Cabella, P.
    Cai, Z. -Y.
    Calvo, M.
    Castellano, M. G.
    Challinor, A.
    Clesse, S.
    Colantoni, I.
    Coppolecchia, A.
    Crook, M.
    D'Alessandro, G.
    Diego, J. -M.
    Di Marco, A.
    Di Valentino, E.
    Errard, J.
    Feeney, S.
    Fernandez-Cobos, R.
    Ferraro, S.
    Finelli, F.
    Forastieri, F.
    Galli, S.
    Genova-Santos, R.
    Gerbino, Martina
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gonzalez-Nuevo, J.
    Grandis, S.
    Greenslade, J.
    Hagstotz, S.
    Hanany, S.
    Handley, W.
    Hernandez-Monteagudo, C.
    Hervias-Caimapo, C.
    Hills, M.
    Hivon, E.
    Kiiveri, K.
    Kisner, T.
    Kitching, T.
    Kunz, M.
    Kurki-Suonio, H.
    Lamagna, L.
    Lasenby, A.
    Lattanzi, M.
    Lesgourgues, J.
    Liguori, M.
    Lindholm, V.
    Lopez-Caniego, M.
    Luzziio, G.
    Maffei, B.
    Mandolesi, N.
    Martinez-Gonzalez, E.
    Martins, C. J. A. P.
    Masi, S.
    Matarrese, S.
    McCarthy, D.
    Melchiorri, A.
    Melin, J. -B.
    Molinari, D.
    Monfardini, A.
    Natoli, P.
    Paiellam, A.
    Paoletti, D.
    Patanchon, G.
    Piat, M.
    Pisano, G.
    Polastri, L.
    Polenta, G.
    Pollo, A.
    Poulin, V.
    Remazeilles, M.
    Roman, M.
    Rubino-Martin, J. -A.
    Salvati, L.
    Tartari, A.
    Tomasi, M.
    Tramonte, D.
    Trappe, N.
    Tucker, C.
    Valiviita, J.
    Van de Weijgaert, R.
    van Tent, B.
    Vennin, V.
    Vielva, P.
    Young, K.
    Zannoni, M.
    Exploring cosmic origins with CORE: Effects of observer peculiar motion2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, article id 021Article in journal (Refereed)
    Abstract [en]

    We discuss the effects on the cosmic microwave background (CMB), cosmic infrared background (CIB), and thermal Sunyaev-Zeldovich effect due to the peculiar motion of an observer with respect to the CMB rest frame, which induces boosting effects. After a brief review of the current observational and theoretical status, we investigate the scientific perspectives opened by future CMB space missions, focussing on the Cosmic Origins Explorer (CORE) proposal. The improvements in sensitivity offered by a mission like CORE, together with its high resolution over a wide frequency range, will provide a more accurate estimate of the CMB dipole. The extension of boosting effects to polarization and cross-correlations will enable a more robust determination of purely velocity-driven effects that are not degenerate with the intrinsic CMB dipole, allowing us to achieve an overall signal-to-noise ratio of 13; this improves on the Planck detection and essentially equals that of an ideal cosmic variance-limited experiment up to a multipole l similar or equal to 2000. Precise inter-frequency calibration will offer the opportunity to constrain or even detect CMB spectral distortions, particularly from the cosmological reionization epoch, because of the frequency dependence of the dipole spectrum, without resorting to precise absolute calibration. The expected improvement with respect to COBE-FIRAS in the recovery of distortion parameters (which could in principle be a factor of several hundred for an ideal experiment with the CORE configuration) ranges from a factor of several up to about 50, depending on the quality of foreground removal and relative calibration. Even in the case of similar or equal to 1% accuracy in both foreground removal and relative calibration at an angular scale of 1 degrees, we find that dipole analyses for a mission like CORE will be able to improve the recovery of the CIB spectrum amplitude by a factor similar or equal to 17 in comparison with current results based on COBE-FIRAS. In addition to the scientific potential of a mission like CORE for these analyses, synergies with other planned and ongoing projects are also discussed.

  • 38. Casadio, Roberto
    et al.
    Kühnel, Florian
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Orlandi, Alessio
    Consistent cosmic microwave background spectra from quantum depletion2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 9, article id 002Article in journal (Refereed)
    Abstract [en]

    Following a new quantum cosmological model proposed by Dvali and Gomez, we quantitatively investigate possible modifications to the Hubble parameter and following corrections to the cosmic microwave background spectrum. In this model, scalar and tensor perturbations are generated by the quantum depletion of the background inflaton and graviton condensate respectively. We show how the inflaton mass affects the power spectra and the tensor-to-scalar ratio. Masses approaching the Planck scale would lead to strong deviations, while standard spectra are recovered for an inflaton mass much smaller than the Planck mass.

  • 39. Catena, Riccardo
    et al.
    Widmark, Axel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Chalmers University of Technology. Sweden.
    WIMP capture by the Sun in the effective theory of dark matter self-interactions2016In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, article id 016Article in journal (Refereed)
    Abstract [en]

    We study the capture of WIMP dark matter by the Sun in the non-relativistic effective theory of dark matter self-interactions. The aim is to assess how self-interactions affect the expected neutrino flux coming from WIMP annihilation in the Sun, and to do so in a model independent manner. We consider all non-relativistic Galilean invariant selfinteraction operators that can arise from the exchange of a heavy particle of spin less than or equal to 1 for WIMPs of spin equal to 0, 1/ 2 and 1. We show that for interaction operators depending at most linearly on the momentum transfer, the WIMP-induced neutrino flux can be enhanced by several orders of magnitude compared to the same flux in absence of self-interactions. This is true even for standard values of the thermally averaged annihilation cross-section. This conclusion impacts the analysis of present and future observations performed at neutrino telescopes.

  • 40. Challinor, A.
    et al.
    Allison, R.
    Carron, J.
    Errard, J.
    Feeney, S.
    Kitching, T.
    Lesgourgues, J.
    Lewis, A.
    Zubeldia, I.
    Achucarro, A.
    Ade, P.
    Ashdown, M.
    Ballardini, M.
    Banday, A. J.
    Banerji, R.
    Bartlett, J.
    Bartolo, N.
    Basak, S.
    Baumann, D.
    Bersanelli, M.
    Bonaldi, A.
    Bonato, M.
    Borri, J.
    Bouchet, F.
    Boulanger, F.
    Brinckmann, T.
    Bucher, M.
    Burigana, C.
    Buzzelli, A.
    Cai, Z. -Y.
    Calvo, M.
    Carvalho, C. -S.
    Castellano, G.
    Chluba, J.
    Clesse, S.
    Colantoni, I.
    Coppolecchia, A.
    Crook, M.
    d'Alessandro, G.
    de Bernardis, P.
    de Gasperis, G.
    De Zotti, G.
    Delabrouille, J.
    Di Valentino, E.
    Diego, J. -M.
    Fernandez-Cobos, R.
    Ferraro, S.
    Finelli, F.
    Forastieri, F.
    Galli, S.
    Genova-Santos, R.
    Gerbino, Martina
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Gonzalez-Nuevo, J.
    Grandis, S.
    Greenslade, J.
    Hagstotz, S.
    Hanany, S.
    Handley, W.
    Hernandez-Monteagudo, C.
    Hervias-Caimapo, C.
    Hills, M.
    Hivon, E.
    Kiiveri, K.
    Kisner, T.
    Kunz, M.
    Kurki-Suonio, H.
    Lamagna, L.
    Lasenby, A.
    Lattanzi, M.
    Liguori, M.
    Lindholm, V.
    Lopez-Caniego, M.
    Luzzi, G.
    Maffei, B.
    Martinez-Gonzalez, E.
    Martins, C. J. A. P.
    Masi, S.
    Matarrese, S.
    McCarthy, D.
    Melchiorri, A.
    Melin, J. -B.
    Molinari, D.
    Monfardini, A.
    Natoli, P.
    Negrello, M.
    Notari, A.
    Paiella, A.
    Paoletti, D.
    Patanchon, G.
    Piat, M.
    Pisano, G.
    Polastri, L.
    Polenta, G.
    Polio, A.
    Poulin, V.
    Quartin, M.
    Remazeilles, M.
    Roman, M.
    Rubino-Martin, J. -A.
    Salvati, L.
    Tartari, A.
    Tomasi, M.
    Tramonte, D.
    Trappe, N.
    Trombetti, T.
    Tucker, C.
    Valiviita, J.
    Van de Weijgaert, R.
    van Tent, B.
    Vennin, V.
    Vielva, P.
    Vittorio, N.
    Young, K.
    Zannoni, M.
    Exploring cosmic origins with CORE: Gravitational lensing of the CMB2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, article id 018Article in journal (Refereed)
    Abstract [en]

    Lensing of the cosmic microwave background (CMB) is now a well-developed probe of the clustering of the large-scale mass distribution over a broad range of redshifts. By exploiting the non-Gaussian imprints of lensing in the polarization of the CMB, the CORE mission will allow production of a clean map of the lensing deflections over nearly the full-sky. The number of high-SAN modes in this map will exceed current CMB lensing maps by a factor of 40, and the measurement will be sample-variance limited on all scales where linear theory is valid. Here, we summarise this mission product and discuss the science that will follow from its power spectrum and the cross-correlation with other clustering data. For example, the summed mass of neutrinos will be determined to an accuracy of 17 meV combining CORE lensing and CMB two-point information with contemporaneous measurements of the baryon acoustic oscillation feature in the clustering of galaxies, three times smaller than the minimum total mass allowed by neutrino oscillation measurements. Lensing has applications across many other science goals of CORE, including the search for B-mode polarization from primordial gravitational waves. Here, lens-induced B-modes will dominate over instrument noise, limiting constraints on the power spectrum amplitude of primordial gravitational waves. With lensing reconstructed by CORE, one can delens the observed polarization internally, reducing the lensing B-mode power by 60 %. This can be improved to 70 % by combining lensing and measurements of the cosmic infrared background from CORE, leading to an improvement of a factor of 2.5 in the error on the amplitude of primordial gravitational waves compared to no delensing (in the null hypothesis of no primordial B-modes). Lensing measurements from CORE will allow calibration of the halo masses of the tens of thousands of galaxy clusters that it will find, with constraints dominated by the clean polarization-based estimators. The 19 frequency channels proposed for CORE will allow accurate removal of Galactic emission from CMB maps. We present initial findings that show that residual Galactic foreground contamination will not be a significant source of bias for lensing power spectrum measurements with CORE.

  • 41. Chen, Pisin
    et al.
    Hu, Yao-Chieh
    Stockholm University, Faculty of Science, Department of Physics. National Taiwan University, Taiwan.
    Yeom, Dong-han
    Fuzzy Euclidean wormholes in de Sitter space2017In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 001Article in journal (Refereed)
    Abstract [en]

    We investigate Euclidean wormholes in Einstein gravity with a massless scalar field in de Sitter space. Euclidean wormholes are possible due to the analytic continuation of the time as well as complexification of fields, where we need to impose the classicality after the Wick-rotation to the Lorentzian signatures. For some parameters, wormholes are preferred than Hawking-Moss instantons, and hence wormholes can be more fundamental than Hawking-Moss type instantons. Euclidean wormholes can be interpreted in three ways: (1) classical big bounce, (2) either tunneling from a small to a large universe or a creation of a collapsing and an expanding universe from nothing, and (3) either a transition from a contracting to a bouncing phase or a creation of two expanding universes from nothing. These various interpretations shed some light on challenges of singularities. In addition, these will help to understand tensions between various kinds of quantum gravity theories.

  • 42. Clifton, Timothy
    et al.
    Gregoris, Daniele
    Stockholm University, Faculty of Science, Department of Physics.
    Rosquist, Kjell
    Stockholm University, Faculty of Science, Department of Physics.
    Tavakol, Reza
    Exact evolution of discrete relativistic cosmological models2013In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 11, p. 010-Article in journal (Refereed)
    Abstract [en]

    We study the effects of inhomogeneities on the evolution of the Universe, by considering a range of cosmological models with discretized matter content. This is done using exact and fully relativistic methods that exploit the symmetries in and about submanifolds of spacetimes that themselves possess no continuous global symmetries. These methods allow us to follow the evolution of our models throughout their entire history, far beyond what has previously been possible. We find that while some space-like curves collapse to anisotropic singularities in finite time, others remain non-singular forever. The resulting picture is of a cosmological spacetime in which some behaviour remains close to Friedmann-like, while other behaviours deviate radically. In particular, we find that large-scale acceleration is possible without any violation of the energy conditions.

  • 43.
    Conrad, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sellerholm, Alexander
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Constraints on cosmological dark matter annihilation from the Fermi-LAT isotropic diffuse gamma-ray measurement2010In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, p. 014-Article in journal (Refereed)
    Abstract [en]

    The first published Fermi large area telescope (Fermi-LAT) measurement of the isotropic diffuse gamma-ray emission is in good agreement with a single power law, and is not showing any signature of a dominant contribution from dark matter sources in the energy range from 20 to 100 GeV. We use the absolute size and spectral shape of this measured flux to derive cross section limits on three types of generic dark matter candidates: annihilat- ing into quarks, charged leptons and monochromatic photons. Predicted gamma-ray fluxes from annihilating dark matter are strongly aected by the underlying distribution of dark matter, and by using different available results of matter structure formation we assess these uncertainties. We also quantify how the dark matter constraints depend on the assumed conventional backgrounds and on the Universe’s transparency to high-energy gamma-rays. In reasonable background and dark matter structure scenarios (but not in all scenarios we consider) it is possible to exclude models proposed to explain the excess of electrons and positrons measured by the Fermi-LAT and PAMELA experiments. Derived limits also start to probe cross sections expected from thermally produced relics (e.g. in minimal supersym- metry models) annihilating predominantly into quarks. For the monochromatic gamma-ray signature, the current measurement constrains only dark matter scenarios with very strong signals.

  • 44. De Zotti, G.
    et al.
    Gonzalez-Nuevo, J.
    Lopez-Caniego, M.
    Negrello, M.
    Greenslade, J.
    Hernandez-Monteagudo, C.
    Delabrouille, J.
    Cai, Z-Y.
    Bonato, M.
    Achucarro, A.
    Ade, P.
    Allison, R.
    Ashdown, M.
    Ballardini, M.
    Banday, A. J.
    Banerji, R.
    Bartlett, J. G.
    Bartolo, N.
    Basak, S.
    Bersanelli, M.
    Biesiada, M.
    Bilicki, M.
    Bonaldi, A.
    Bonavera, L.
    Borrill, J.
    Bouchet, F.
    Boulanger, F.
    Brinckmann, T.
    Bucher, M.
    Burigana, C.
    Buzzelli, A.
    Calvo, M.
    Carvalho, C. S.
    Castellano, M. G.
    Challinor, A.
    Chluba, J.
    Clements, D. L.
    Clesse, S.
    Colafrancesco, S.
    Colantoni, I.
    Coppolecchia, A.
    Crook, M.
    D'Alessandro, G.
    de Bernardis, P.
    de Gasperis, G.
    Diego, J. M.
    Di Valentino, E.
    Errard, J.
    Feeney, S. M.
    Fernandez-Cobos, R.
    Ferraro, S.
    Finelli, F.
    Forastieri, F.
    Galli, S.
    Genova-Santos, R. T.
    Gerbino, Martina
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Grandis, S.
    Hagstotz, S.
    Hanany, S.
    Handley, W.
    Hervias-Caimapo, C.
    Hills, M.
    Hivon, E.
    Kiiveri, K.
    Kisner, T.
    Kitching, T.
    Kunz, M.
    Kurki-Suonio, H.
    Lagache, G.
    Lamagna, L.
    Lasenby, A.
    Lattanzi, M.
    Le Brun, A.
    Lesgourgues, J.
    Lewis, A.
    Liguori, M.
    Lindholm, V.
    Luzzi, G.
    Maffei, B.
    Mandolesi, N.
    Martinez-Gonzalez, E.
    Martins, C. J. A. P.
    Masi, S.
    Massardi, M.
    Matarrese, S.
    McCarthy, D.
    Melchiorri, A.
    Melin, J-B.
    Molinari, D.
    Monfardini, A.
    Natoli, P.
    Notari, A.
    Paiella, A.
    Paoletti, D.
    Partridge, R. B.
    Patanchon, G.
    Piat, M.
    Pisano, G.
    Polastri, L.
    Polenta, G.
    Pollo, A.
    Poulin, V.
    Quartin, M.
    Remazeilles, M.
    Roman, M.
    Rossi, G.
    Roukema, B. F.
    Rubino-Martin, J-A.
    Salvati, L.
    Scott, D.
    Serjeant, S.
    Tartari, A.
    Toffolatti, L.
    Tomasi, M.
    Trappe, N.
    Triqueneaux, S.
    Trombetti, T.
    Tucci, M.
    Tucker, C.
    Valiviita, J.
    van de Weygaert, R.
    Van Tent, B.
    Vennin, V.
    Vielva, P.
    Vittorio, N.
    Young, K.
    Zannoni, M.
    Exploring cosmic origins with CORE: Extragalactic sources in cosmic microwave background maps2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, article id 020Article in journal (Refereed)
    Abstract [en]

    We discuss the potential of a next generation space-borne Cosmic Microwave Background (CMB) experiment for studies of extragalactic sources. Our analysis has particular bearing on the definition of the future space project, CORE, that has been submitted in response to ESA's call for a Medium-size mission opportunity as the successor of the Planck satellite. Even though the effective telescope size will be somewhat smaller than that of Planck, CORE will have a considerably better angular resolution at its highest frequencies, since, in contrast with Planck, it will be diffraction limited at all frequencies. The improved resolution implies a considerable decrease of the source confusion, i.e. substantially fainter detection limits. In particular, CORE will detect thousands of strongly lensed high-z galaxies distributed over the full sky. The extreme brightness of these galaxies will make it possible to study them, via follow-up observations, in extraordinary detail. Also, the CORE resolution matches the typical sizes of high-z galaxy proto-clusters much better than the Planck resolution, resulting in a much higher detection efficiency; these objects will be caught in an evolutionary phase beyond the reach of surveys in other wavebands. Furthermore, CORE will provide unique information on the evolution of the star formation in virialized groups and clusters of galaxies up to the highest possible redshifts. Finally, thanks to its very high sensitivity, CORE will detect the polarized emission of thousands of radio sources and, for the first time, of dusty galaxies, at mm and sub-mm wavelengths, respectively.

  • 45. Delabrouille, J.
    et al.
    de Bernardis, P.
    Bouchet, F. R.
    Achucarro, A.
    Ade, P. A. R.
    Allison, R.
    Arroja, F.
    Artal, E.
    Ashdown, M.
    Baccigalupi, C.
    Ballardini, M.
    Banday, A. J.
    Banerji, R.
    Barbosa, D.
    Bartlett, J.
    Bartolo, N.
    Basak, S.
    Baselmans, J. J. A.
    Basu, K.
    Battistelli, E. S.
    Battye, R.
    Baumann, D.
    Benoit, A.
    Bersanelli, M.
    Bideaud, A.
    Biesiada, M.
    Bilicki, M.
    Bonaldi, A.
    Bonato, M.
    Borrill, J.
    Boulanger, F.
    Brinckmann, T.
    Brown, M. L.
    Bucher, M.
    Burigana, C.
    Buzzelli, A.
    Cabass, G.
    Cai, Z. -Y.
    Calvo, M.
    Caputo, A.
    Carvalho, C. -S.
    Casas, F. J.
    Castellano, G.
    Catalano, A.
    Challinor, A.
    Charles, I.
    Chluba, J.
    Clements, D. L.
    Clesse, S.
    Colafrancesco, S.
    Colantoni, I.
    Contreras, D.
    Coppolecchia, A.
    Crook, M.
    D'Alessandro, G.
    D'Amico, G.
    da Silva, A.
    de Avillez, M.
    de Gasperis, G.
    De Petris, M.
    de Zotti, G.
    Danese, L.
    Desert, F. -X.
    Desjacques, V.
    Di Valentino, E.
    Dickinson, C.
    Diego, J. M.
    Doyle, S.
    Durrer, R.
    Dvorkin, C.
    Eriksen, H. K.
    Errard, J.
    Feeney, S.
    Fernandez-Cobos, R.
    FineIli, F.
    Forastieri, F.
    Franceschet, C.
    Fuskeland, U.
    Galli, S.
    Genova-Santos, R. T.
    Gerbino, Martina
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Giusarma, E.
    Gomez, A.
    Gonzalez-Nuevo, J.
    Grandis, S.
    Greenslade, J.
    Goupy, J.
    Hagstotz, S.
    Hanany, S.
    Handley, W.
    Henrot-Versille, S.
    Hernandez-Monteagudo, C.
    Hervias-Caimapo, C.
    Hills, M.
    Hindmarsh, M.
    Hivon, E.
    Hoang, D. T.
    Hooper, D. C.
    Hu, B.
    Keihanen, E.
    Keskitalo, R.
    Kiiveri, K.
    Kisner, T.
    Kitching, T.
    Kunz, M.
    Kurki-Suonio, H.
    Lagache, G.
    Lamagna, L.
    Lapi, A.
    Lasenby, A.
    Lattanzi, M.
    Le Brun, A. M. C.
    Lesgourgues, J.
    Liguori, M.
    Lindholm, V.
    Lizarraga, J.
    Luzzi, G.
    Macias-Perez, J. F.
    Maffei, B.
    Mandolesi, N.
    Martin, S.
    Martinez-Gonzalez, E.
    Martins, C. J. A. P.
    Masi, S.
    Massardi, M.
    Matarrese, S.
    Mazzotta, P.
    McCarthy, D.
    Melchiorri, A.
    Melin, J. -B.
    Mennella, A.
    Mohr, J.
    Molinari, D.
    Monfardini, A.
    Montier, L.
    Natoli, P.
    Negrello, M.
    Notari, A.
    Noviello, F.
    Oppizzi, F.
    O'Sullivan, C.
    Pagano, L.
    Paiella, A.
    Pajer, E.
    Paoletti, D.
    Paradiso, S.
    Partridge, R. B.
    Patanchon, G.
    Patil, S. P.
    Perdereau, O.
    Piacentini, F.
    Piat, M.
    Pisano, G.
    Polastri, L.
    Polenta, G.
    Pollo, A.
    Ponthieu, N.
    Poulin, V.
    Prele, D.
    Quartin, M.
    Ravenni, A.
    Remazeilles, M.
    Renzi, A.
    Ringeval, C.
    Roest, D.
    Roman, M.
    Roukema, B. F.
    Rubino-Martin, J. -A.
    Salvati, L.
    Scott, D.
    Serjeant, S.
    Signorelli, G.
    Starobinsky, A. A.
    Sunyaev, R.
    Tan, C. Y.
    Tartari, A.
    Tasinato, G.
    Toffolatti, L.
    Tomasi, M.
    Torrado, J.
    Tramonte, D.
    Trappe, N.
    Triqueneaux, S.
    Tristram, M.
    Trombetti, T.
    Tucci, M.
    Tucker, C.
    Urrestilla, J.
    Valiviita, J.
    Van de Weygaert, R.
    Van Tent, B.
    Vennin, V.
    Verde, L.
    Vermeulen, G.
    Vielva, P.
    Vittorio, N.
    Voisin, F.
    Wallis, C.
    Wandelt, B.
    Wehus, I. K.
    Weller, J.
    Young, K.
    Zannoni, M.
    Exploring cosmic origins with CORE: Survey requirements and mission design2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, article id 014Article in journal (Refereed)
    Abstract [en]

    Future observations of cosmic microwave background (CMB) polarisation have the potential to answer some of the most fundamental questions of modern physics and cosmology, including: what physical process gave birth to the Universe we see today? What are the dark matter and dark energy that seem to constitute 95% of the energy density of the Universe? Do we need extensions to the standard model of particle physics and fundamental interactions? Is the ACDM cosmological scenario correct, or are we missing an essential piece of the puzzle? In this paper, we list the requirements for a future CMB polarisation survey addressing these scientific objectives, and discuss the design drivers of the CORE space mission proposed to ESA in answer to the M5 call for a medium-sized mission. The rationale and options, and the methodologies used to assess the mission's performance, are of interest to other future CMB mission design studies. CORE has 19 frequency channels, distributed over a broad frequency range, spanning the 60-600 GHz interval, to control astrophysical foreground emission. The angular resolution ranges from 2' to 18', and the aggregate CMB sensitivity is about 2 mu K.arcmin. The observations are made with a single integrated focal-plane instrument, consisting of an array of 2100 cryogenically-cooled, linearly-polarised detectors at the focus of a 1.2-m aperture cross-Dragone telescope. The mission is designed to minimise all sources of systematic effects, which must be controlled so that no more than 10(-4) of the intensity leaks into polarisation maps, and no more than about 1% of E-type polarisation leaks into B-type modes. CORE observes the sky from a large Lissajous orbit around the Sun-Earth L2 point on an orbit that offers stable observing conditions and avoids contamination from sidelobe pick-up of stray radiation originating from the Sun, Earth, and Moon. The entire sky is observed repeatedly during four years of continuous scanning, with a combination of three rotations of the spacecraft over different timescales. With about 50% of the sky covered every few days, this scan strategy provides the mitigation of systematic effects and the internal redundancy that are needed to convincingly extract the primordial B-mode signal on large angular scales, and check with adequate sensitivity the consistency of the observations in several independent data subsets. CORE is designed as a near-ultimate CMB polarisation mission which, for optimal complementarity with ground-based observations, will perform the observations that are known to be essential to CMB polarisation science and cannot be obtained by any other means than a dedicated space mission. It will provide well-characterised, highly-redundant multi-frequency observations of polarisation at all the scales where foreground emission and cosmic variance dominate the final uncertainty for obtaining precision CMB science, as well as 2' angular resolution maps of high-frequency foreground emission in the 300-600 GHz frequency range, essential for complementarity with future ground-based observations with large telescopes that can observe the CMB with the same beamsize.

  • 46.
    Delahaye, Timur
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Grefe, Michael
    Antideuterons from decaying gravitino dark matter2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 012Article in journal (Refereed)
    Abstract [en]

    We study the possibility of improving the constraints on the lifetime of gravitino dark matter in scenarios with bilinear R-parity violation by estimating the amount of cosmicray antideuterons that can be produced in gravitino decays. Taking into account all different sources of theoretical uncertainties, we find that the margin of improvement beyond the limits already set by cosmic-ray antiproton data are quite narrow and unachievable for the next generation of experiments. However, we also identify more promising energy ranges for future experiments.

  • 47. Demozzi, Vittoria
    et al.
    Mukhanov, Viatcheslav
    Rubinstein, Hector
    Stockholm University, Faculty of Science, Department of Physics.
    Magnetic fields from inflation?2009In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, p. 25-Article in journal (Refereed)
    Abstract [en]

    We consider the possibility of generation of the primordial magnetic field on inflation and show that the effect of the back reaction of this field can be very important. Assuming that the back reaction does not spoil inflation we find a rather strong restriction on the amplitude of the primordial field which could be generated on inflation. Namely, this amplitude recalculated to the present epoch cannot exceed 10(-32)G in Mpc scales. This field seems to be too small to be amplified to the observable values by a possible dynamo mechanism.

  • 48.
    Dhawan, Suhail
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mörtsell, Edvard
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    The effect of inhomogeneities on dark energy constraints2018In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 024Article in journal (Refereed)
    Abstract [en]

    Constraints on models of the late time acceleration of the universe assume the cosmological principle of homogeneity and isotropy on large scales. However, small scale inhomogeneities can alter observational and dynamical relations, affecting the inferred cosmological parameters. For precision constraints on the properties of dark energy, it is important to assess the potential systematic effects arising from these inhomogeneities. In this study, we use the Type Ia supernova magnitude-redshift relation to constrain the inhomogeneities as described by the Dyer-Roeder distance relation and the effect they have on the dark energy equation of state (w), together with priors derived from the most recent results of the measurements of the power spectrum of the Cosmic Microwave Background and Baryon Acoustic Oscillations. We find that the parameter describing the inhomogeneities (eta) is weakly correlated with w. The best fit values w = -0.933 +/- 0.065 and eta = 0.61 +/- 0.37 are consistent with homogeneity at < 2 sigma level. Assuming homogeneity (eta = 1), we find w = -0.961 +/- 0.055, indicating only a small change in w. For a time-dependent dark energy equation of state, w(0) = -0.951 +/- 0.112 and w(a) = 0.059 +/- 0.418, to be compared with w(0) = -0.983 +/- 0.127 and w(a) = 0.07 +/- 0.432 in the homogeneous case, which is also a very small change. We do not obtain constraints on the fraction of dark matter in compact objects, f(p), at the 95% C.L. with conservative corrections to the distance formalism. Future supernova surveys will improve the constraints on eta, and hence, f(p), by a factor of similar to 10.

  • 49.
    Dhawan, Suhail
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Goobar, Ariel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Mörtsell, Edvard
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Amanullah, Rahman
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Feindt, Ulrich
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Narrowing down the possible explanations of cosmic acceleration with geometric probes2017In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 040Article in journal (Refereed)
    Abstract [en]

    Recent re-calibration of the Type Ia supernova (SNe Ia) magnitude-redshift relation combined with cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) data have provided excellent constraints on the standard cosmological model. Here, we examine particular classes of alternative cosmologies, motivated by various physical mechanisms, e.g. scalar fields, modified gravity and phase transitions to test their consistency with observations of SNe Ia and the ratio of the angular diameter distances from the CMB and BAO. Using a model selection criterion for a relative comparison of the models (the Bayes Factor), we find moderate to strong evidence that the data prefer flat Lambda CDM over models invoking a thawing behaviour of the quintessence scalar field. However, some exotic models like the growing neutrino mass cosmology and vacuum metamorphosis still present acceptable evidence values. The bimetric gravity model with only the linear interaction term as well as a simplified Galileon model can be ruled out by the combination of SNe Ia and CMB/BAO datasets whereas the model with linear and quadratic interaction terms has a comparable evidence value to standard Lambda CDM. Thawing models are found to have significantly poorer evidence compared to flat Lambda CDM cosmology under the assumption that the CMB compressed likelihood provides an adequate description for these non-standard cosmologies. We also present estimates for constraints from future data and find that geometric probes from oncoming surveys can put severe limits on non-standard cosmological models.

  • 50. Di Bari, Pasquale
    et al.
    King, Stephen F.
    Luhn, Christoph
    Merle, Alexander
    Schmidt-May, Angnis
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Radiative inflation and dark energy RIDEs again after BICEP22014In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 8, p. 040-Article in journal (Refereed)
    Abstract [en]

    Following the ground-breaking measurement of the tensor-to-scalar ratio r = 0.20(-0.05)(+0.07) by the BICEP2 collaboration, we perform a statistical analysis of a model that combines Radiative Inflation with Dark Energy (RIDE) based on the M-2 vertical bar Phi vertical bar(2) ln (vertical bar Phi vertical bar(2)/Lambda(2)) potential and compare its predictions to those based on the traditional chaotic inflation M-2 vertical bar Phi vertical bar(2) potential. We find a best-fit value in the RIDE model of r = 0.18 as compared to r = 0.17 in the chaotic model, with the spectral index being n(S) = 0.96 in both models.

123 1 - 50 of 115
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