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  • 1.
    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).
    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).
    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).
    Hultqvist, Klas
    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).
    Astrophysical neutrinos and cosmic rays observed by IceCube2018In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 62, no 10, p. 2902-2930Article in journal (Refereed)
    Abstract [en]

    The core mission of the IceCube neutrino observatory is to study the origin and propagation of cosmic rays. IceCube, with its surface component IceTop, observes multiple signatures to accomplish this mission. Most important are the astrophysical neutrinos that are produced in interactions of cosmic rays, close to their sources and in interstellar space. IceCube is the first instrument that measures the properties of this astrophysical neutrino flux and constrains its origin. In addition, the spectrum, composition, and anisotropy of the local cosmic-ray flux are obtained from measurements of atmospheric muons and showers. Here we provide an overview of recent findings from the analysis of IceCube data, and their implications to our understanding of cosmic rays.

  • 2. Dikpati, Mausumi
    et al.
    Mitra, Dhrubaditya
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
    Anderson, Jeffrey L.
    Role of response time of a Babcock-Leighton solar dynamo model in meridional flow-speed reconstruction by EnKF data assimilation2016In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 58, no 8, p. 1589-1595Article in journal (Refereed)
    Abstract [en]

    Ensemble Kalman Filter in the framework of Data Assimilation Research Testbed (DART) has been successfully implemented into a 2D kinematic flux-transport dynamo model by Dikpati and colleagues in order to do a parameter estimation, the parameter being the meridional flow-speed as function of time. They performed several 'Observing System Simulation Experiments' (OSSEs), and showed that an optimal reconstruction of time-series of meridional flow-speed can be obtained by using 16 ensemble members and only one surface magnetic observation with 30% observational error. Error in reconstruction can be reduced by increasing the ensemble size and number of observations. However, this parameter reconstruction has been found to be sensitive to locations from where observational data are taken. While assimilation of low-latitudes' surface poloidal magnetic field data can produce good reconstruction, medium frequency oscillations appear in time-series of reconstructed flow-speed if tachocline toroidal field data are assimilated. These oscillations occur primarily because tachocline toroidal fields change very little during an assimilation interval taken to be 15 days, due to changes in meridional flow. A Babcock-Leighton dynamo model's response time to changes in meridional flow-speed is a few months. We show here that rms error in reconstruction can be significantly reduced if model's response time is taken into consideration in assimilation of tachocline toroidal field data.

  • 3.
    Hedin, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Waldemarsson, Tomas
    Stockholm University, Faculty of Science, Department of Meteorology .
    Giovane, Frank
    Naval Research Laboratory, Washington, DC.
    The aerodynamics of the MAGIC meteoric smoke sampler2007In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 40, no 6, p. 818-824Article in journal (Refereed)
    Abstract [en]

    The detection of nanometre-sized meteoric smoke particles in the Earth’s mesosphere and lower thermosphere is difficult. The particles are too small for optical detection and so far only the charged fraction of the particles has been probed by rocket-borne instruments. One way to obtain maximum information about the smoke particles is direct sampling with rocket-borne particle samplers. The MAGIC project (Mesospheric Aerosol – Genesis, Interaction and Composition) aims to quantitatively answer fundamental questions about the properties of smoke in the atmosphere. The first launch of such particle samplers was performed during the MAGIC rocket campaign from Esrange, Sweden, in January 2005. In order to characterise the sampling process, we have performed simulations of the trajectories of nanometre-sized dust particles towards the MAGIC detectors with a new particle motion model. An important feature of this model is the Brownian motion of the particles due to thermal collisions of the gas molecules. As a result, we obtain the detection efficiency for the MAGIC detectors as a function of altitude and particle size. Our simulations confirm that particles of radii down to 0.75 nm impact on the sampling surface with an efficiency exceeding 80% over the entire mesospheric altitude range of interest.

  • 4. Hjalmarson, Åke
    et al.
    Bergman, Per
    Biver, Nicolas
    Florén, H.-G.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Frisk, Urban
    Hasegawa, Tatsuhiko
    Justtanont, Kay
    Stockholm University, Faculty of Science, Department of Astronomy.
    Larsson, Bengt
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundin, Stefan
    Olberg, Michael
    Olofsson, Henrik
    Persson, Glenn
    Rydbeck, Gustaf
    Sandqvist, Aage
    Stockholm University, Faculty of Science, Department of Astronomy.
    The Odin Team,
    Recent astronomy highlights from the Odin satellite2005In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 36, p. 1031-1047Article in journal (Refereed)
    Abstract [en]

    Astronomy highlights, mainly from the third year of Odin observations time shared 50/50% with aeronomy are presented: the very low O2 abundance limits achieved, the highly pressure broadened absorption lines of H2O, H218O, and CO (5 → 4) in the atmosphere of Mars, the high precision H2O and H218O observations of comets, the detections of NH3 and H2O around the C-rich star IRC+10216 (CW Leo) and of H2O around the O-rich star W Hya, NH3 and H2O observations of infall/outflow interactions, observations of H2O, H218O, H217O as well as NH3 and 15NH3 in multiple absorptions towards Sgr B2, and in emission towards Orion KL, the H2O detection of several new outflows in the DR21 W75S region. We also discuss the results of deconvolution of high S/N H2O, CO and 13CO (5 → 4) maps of the Orion KL region to 40″ resolution (the beam size of the Herschel telescope) and the first results from our ongoing “spectral scan” of Orion KL in bands around 555 and 570 GHz. Finally, a search for primordial molecules is presented.

  • 5. Jurčák, Jan
    et al.
    Collados, Manuel
    Leenaarts, Jorrit
    Stockholm University, Faculty of Science, Department of Astronomy.
    van Noort, Michiel
    Schlichenmaier, Rolf
    Recent advancements in the EST project2019In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 63, no 4, p. 1389-1395Article in journal (Refereed)
    Abstract [en]

    The European Solar Telescope (EST) is a project of a new-generation solar telescope. It has a large aperture of 4 m, which is necessary for achieving high spatial and temporal resolution. The high polarimetric sensitivity of the EST will allow to measure the magnetic field in the solar atmosphere with unprecedented precision. Here, we summarise the recent advancements in the realisation of the EST project regarding the hardware development and the refinement of the science requirements.

  • 6. Kosenko, D. I.
    et al.
    Blinnikov, S. I.
    Postnov, K. A.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Sorokina, E. I.
    Time-dependent thermal X-ray afterglows from GRBS2004In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 34, p. 2705-2710Article in journal (Refereed)
    Abstract [en]

    Time-dependent thermal X-ray spectra are calculated from physically plausible conditions around GRB. It is shown that account for time-dependent ionization processes strongly affects the observed spectra of hot rarefied plasma. These calculations may provide an alternative explanation to the observed X-ray lines of early GRBs afterglows (such as GRB 011211). Our technique will allow one to obtain independent constraints on the GRB collimation angle and on the clumpiness of circumstellar matter.

  • 7. Kosenko, D. I.
    et al.
    Sorokina, E. I.
    Blinnikov, S. I.
    Lundqvist, P.
    Stockholm University, Faculty of Science, Department of Astronomy.
    X-ray emission of young SN Ia remnants as a probe for an explosion model2004In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 33, p. 392-397Article in journal (Refereed)
    Abstract [en]

    We present results of hydrodynamical simulations of young supernova remnants. To model the ejecta, we use several models (discussed in the literature) of type Ia supernova explosions with different abundances. Our hydro models are one-dimensional and spherically symmetrical, but they take into account ionization kinetics with all important processes. We include detailed calculations for the X-ray emission, allowing for time-dependent ionization and recombination. In particular, we compare the computed X-ray spectra with recent XMM-Newton observations of the Tycho supernova remnant (SNR). Our goal is to find the most viable thermonuclear SN model that gives good fits to both these X-ray observations and typical SN Ia light curves.

  • 8.
    Körnich, Heiner
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Becker, Erich
    A simple model for the interhemispheric coupling of the middle atmosphere circulation2010In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 45, no 5, p. 661-668Article in journal (Refereed)
    Abstract [en]

    The interhemispheric coupling of the middle atmosphere general circulation is characterized by a global anomaly pattern of the zonal-mean temperature. This pattern reflects an anomalous stratospheric and mesospheric residual circulation, in which a weaker (stronger) stratospheric winter circulation is linked to an upward (downward) shift of its upper mesospheric branch reaching from the summer to the winter pole. This phenomenon is robust in observational data and several middle atmosphere general circulation models. In the present study, the recently proposed mechanism of the interhemispheric coupling is unequivocally proven within the framework of a zonally symmetric model that excludes any additional effects due to resolved waves and non-zonally propagating gravity waves. Two simulations are conducted that differ in the strength of the polar vortex. A weaker polar vortex results in a downward shift of the winter mesospheric gravity wave drag. This leads to changes also in the summer upper mesosphere via a feedback solely between gravity wave breaking and the zonal-mean state. The accompanying temperature anomaly reproduces the pattern of the interhemispheric coupling. (C) 2009 COSPAR.

  • 9. Leonov, A. A.
    et al.
    Galper, A. M.
    Bonvicini, V.
    Topchiev, N. P.
    Adriain, O.
    Aptekar, R. L.
    Arkhangelskaja, I. V.
    Arkhangelskiy, A. I.
    Bergström, Lars
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Berti, E.
    Bigongiari, G.
    Bobkov, S. G.
    Boezio, M.
    Bogomolov, E. A.
    Bonechi, S.
    Bongi, M.
    Bottai, S.
    Castellini, G.
    Cattaneo, P. W.
    Cumani, P.
    Dedenko, G. L.
    De Donato, C.
    Dogiel, V. A.
    Gorbunov, M. S.
    Gusakov, Yu. V.
    Hnatyk, B. I.
    Kadilin, V. V.
    Kaplin, V. A.
    Kaplun, A. A.
    Kheymits, M. D.
    Korepanov, V. E.
    Larsson, J.
    Loginov, V. A.
    Longo, F.
    Maestro, P.
    Marrocchesi, P. S.
    Mikhailov, V. V.
    Mocchiutti, E.
    Moiseev, A. A.
    Mori, N.
    Moskalenko, I. V.
    Naumov, P. Yu.
    Papini, P.
    Pearce, M.
    Picozza, P.
    Rappoldi, A.
    Ricciarini, S.
    Runtso, M. F.
    Ryde, F.
    Serdin, O. V.
    Sparvoli, R.
    Spillantini, P.
    Suchkov, S. I.
    Taraskin, A. A.
    Tavani, M.
    Tiberio, A.
    Tyurin, E. M.
    Ulanov, M. V.
    Vacchi, A.
    Vannuccini, E.
    Vasilyev, G. I.
    Yurkin, Yu. T.
    Zampa, N.
    Zirakashvili, V. N.
    Zverev, V. G.
    Separation of electrons and protons in the GAMMA-400 gamma-ray telescope2015In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 56, no 7, p. 1538-1545Article in journal (Refereed)
    Abstract [en]

    The GAMMA-400 telescope will measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. These measurements will allow it to achieve the following scientific objectives: search for signatures of dark matter, investigation of gamma-ray point-like and extended sources, study of the energy spectrum of the Galactic and extragalactic diffuse emission, study of gamma-ray bursts and gamma-ray emission from the active Sun, together with high-precision measurements of the high-energy electrons and positrons spectra, protons and nuclei up to the knee. The bulk of cosmic rays are protons and helium nuclei, whereas the lepton component in the total flux is similar to 10(-3) at high energy. In the present paper, the simulated capability of the GAMMA-400 telescope to distinguish electrons and positrons from protons in cosmic rays is addressed. The individual contribution to the proton rejection from each detector system of GAMMA-400 is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of the order of similar to 4 x 10(5) for vertical incident particles and similar to 3 x 10(5) for particles with initial inclination of 30 degrees in the electron energy range from 50 GeV to 1 TeV. (C) 2015 COSPAR.

  • 10.
    Lossow, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Urban, Joachim
    Chalmers University of Technology, Department of Radio and Space Science.
    Eriksson, Patrick
    Chalmers University of Technology, Department of Radio and Space Science.
    Murtagh, Donal
    Chalmers University of Technology, Department of Radio and Space Science.
    Gumbel, Jörg
    Stockholm University, Faculty of Science, Department of Meteorology .
    Critical parameters for the retrieval of mesospheric water vapour and tempera- ture from Odin/SMR limb measurements at 557 GHz2007In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 40, no 6, p. 835-845Article in journal (Refereed)
    Abstract [en]

    Limb measurements at 557 GHz by the Sub-millimetre and Millimetre Radiometer (SMR) onboard the Odin satellite provide water vapour and temperature information throughout the mesosphere. A sensitivity study for these retrievals has been performed, in order to identify the most critical parameters affecting the retrievals, with focus on the polar summer mesosphere conditions. Uncertainties in the instrument characterisation and the a priori value chosen for the pointing offset were found to have significant effects on the retrieved profiles. It is also shown that spectroscopic parameters play a role. An obvious improvement of the water and temperature retrieval can be obtained when we account for some of these critical parameters. However, some further improvement of the instrument behaviour characterisation is still needed

  • 11.
    Serafimovich, Natalia I.
    et al.
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lundqvist, Peter
    Stockholm University, Faculty of Science, Department of Astronomy.
    Shibanov, Yu. A.
    Sollerman, Jesper
    Stockholm University, Faculty of Science, Department of Astronomy.
    Optical observations of the young supernova remnant SNR 0540-69.3 and its pulsar2005In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 35, no 6, p. 1106-1111Article in journal (Refereed)
    Abstract [en]

    We have used the ESO NTT/EMMI and VLT/FORS1 instruments to examine the LMC supernova remnant 0540-69.3 as well as its pulsar (PSR B0540-69) and pulsar-powered nebula in the optical range. Spectroscopic observations of the remnant covering the range of 3600 7350 Å centered on the pulsar produced results consistent with those of [Kirshner, R.P., Morse, J.A., Winkler, P.F., et al. The penultimate supernova in the Large Magellanic Cloud - SNR 0540-69.3. Astrophys.J. 342, 260 271, 1989.] but also revealed many new emission lines. The most important are [Ne III] λλ3869, 3967 and Balmer lines of hydrogen. In both the central part of the remnant, as well as in nearby H II regions, the [O III] temperature is higher than ˜2 × 104 K, but lower than previously estimated. For PSR B0540-69, previous optical data are mutually inconsistent: HST/FOS spectra indicate a significantly higher absolute flux and steeper spectral index than suggested by early time-resolved groundbased UBVRI photometry. We show that the HST and VLT spectroscopic data for the pulsar have ≳50% nebular contamination, and that this is the reason for the previous difference. Using HST/WFPC2 archival images obtained in various bands from the red part of the optical to the NUV range we have performed an accurate photometric study of the pulsar, and find that the spectral energy distribution of the pulsar emission has a negative slope with α=1.07-0.19+0.20. This is steeper than derived from previous UBVRI photometry, and also different from the almost flat spectrum of the Crab pulsar. We also estimate that the proper motion of the pulsar is 4.9 ± 2.3 mas year‑1, corresponding to a transverse velocity of 1190 ± 560 km s‑1, projected along the southern jet of the pulsar nebula.

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