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  • 301.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Universums största stjärna2012Inngår i: Forskning och framsteg, ISSN 0015-7937, nr 9, s. 18-22Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Nyligen trodde astronomerna att stjärnor inte kunde bli större än 150 solmassor. Nya fynd visar att stjärnorna förmodligen kan bli dubbelt så stora – och dessa jättar spelar en avgörande roll för rymdens utveckling.

  • 302.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Inserra, C.
    Valenti, S.
    Wilson, P. A.
    Jon Juliusson, S.
    Holma, H.
    Ingemyr, M.
    Saxen, O.
    Haukanes, L.
    Supernova 2009md in NGC 33892009Inngår i: Central Bureau Electronic Telegrams, Vol. 2068, s. 1-Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    CBET 2068 available at Central Bureau for Astronomical Telegrams.

  • 303.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, C.
    Horesh, A.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, S.
    Sfaradi, I.
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bellm, E. C.
    Burruss, R.
    Cunningham, V.
    De, K.
    Drake, A. J.
    Golkhou, V. Z.
    Green, D. A.
    Kasliwal, M.
    Kulkarni, S.
    Kupfer, T.
    Laher, R. R.
    Masci, F. J.
    Rodriguez, H.
    Rusholme, B.
    Williams, D. R. A.
    Yan, L.
    Zolkower, J.
    Two stripped envelope supernovae with circumstellar interaction: But only one really shows it2020Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 643, artikkel-id A79Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. We present observations of SN 2019tsf (ZTF19ackjszs) and SN 2019oys (ZTF19abucwzt). These two stripped envelope (SE) Type Ib supernovae (SNe) suddenly showed a (re-)brightening in their late light curves. We investigate this in the context of circumstellar material (CSM) interaction with previously ejected material, a phenomenon that is unusual among SE SNe.

    Aims. We use our follow-up photometry and spectroscopy for these supernovae to demonstrate the presence of CSM interaction, estimate the properties of the CSM, and discuss why the signals are so different for the two objects.

    Methods. We present and analyze observational data, consisting of optical light curves and spectra. For SN 2019oys, we also have detections in radio as well as limits from UV and X-rays.

    Results. Both light curves show spectacular re-brightening after about 100 days. In the case of SN 2019tsf, the re-brightening is followed by a new period of decline, and the spectra never show signs of narrow emission lines that would indicate CSM interaction. On the contrary, SN 2019oys made a spectral makeover from a Type Ib to a spectrum clearly dominated by CSM interaction at the light curve brightening phase. Deep Keck spectra reveal a plethora of narrow high-ionization lines, including coronal lines, and the radio observations show strong emission.

    Conclusions. The rather similar light curve behavior – with a late linear re-brightening – of these two Type Ib SE SNe indicate CSM interaction as the powering source. For SN 2019oys the evidence for a phase where the ejecta hit H-rich material, likely ejected from the progenitor star, is conspicuous. We observe strong narrow lines of H and He, but also a plethora of high-ionization lines, including coronal lines, revealing shock interaction. Spectral simulations of SN 2019oys show two distinct density components, one with density ≳109 cm−3, dominated by somewhat broader, low-ionization lines of H I, He I, Na I, and Ca II, and one with narrow, high-ionization lines at a density ∼106 cm−3. The former is strongly affected by electron scattering, while the latter is unaffected. The evidence for CSM interaction in SN 2019oys is corroborated by detections in radio. On the contrary, for SN 2019tsf, we find little evidence in the spectra for any CSM interaction.

     

  • 304.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Nobelpriset i Fysik 20112012Inngår i: Kosmos, ISSN 0368-6213, nr 2011, s. 7-16Artikkel, forskningsoversikt (Annet (populærvitenskap, debatt, mm))
  • 305.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Leloudas, G
    Supernova 2007rb in NGC 28892007Annet (Annet vitenskapelig)
  • 306.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lindler, Don
    Chevalier, Roger A.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Gull, Theodore R.
    Pun, Chun S. J.
    Sonneborn, George
    Observations of the Crab Nebula and Its Pulsar in the Far-Ultraviolet and in the Optical2000Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 537, s. 861-874Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present far-UV observations of the Crab Nebula and its pulsar made with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Broad, blueshifted absorption arising in the nebula is seen in C IV λ1550, reaching a blueward velocity of ~2500 km s-1. This can be interpreted as evidence for a fast outer shell surrounding the Crab Nebula, and we adopt a spherically symmetric model to constrain the properties of such a shell. From the line profile we find that the density appears to decrease outward in the shell. A likely lower limit to the shell mass is ~0.3 Msolar with an accompanying kinetic energy of ~1.5×1049 ergs. A fast massive shell with 1051 ergs cannot be excluded but is less likely if the density profile is much steeper than ρ(R)~R-4 and the maximum velocity is <~6000 km s-1. The observations cover the region 1140-1720 Å, which is further into the ultraviolet than has previously been obtained for the pulsar. With the time-tag mode of the spectrograph we obtain the pulse profile in this spectral regime. The profile is similar to that previously obtained by us in the near-UV, although the primary peak is marginally narrower. Together with the near-UV data, and new optical data from the Nordic Optical Telescope, our spectrum of the Crab pulsar covers the entire region from 1140 to 9250 Å. Dereddening the spectrum with a standard extinction curve we achieve a flat spectrum for the reddening parameters E(B-V)=0.52, R=3.1. This dereddened spectrum of the Crab pulsar can be fitted by a power law with spectral index αν=0.11+/-0.04. The main uncertainty in determining the spectral index is the amount and characteristics of the interstellar reddening, and we have investigated the dependence of αν on E(B-V) and R. In the extended emission covered by our 25''×0.5" slit in the far-UV, we detect C IV λ1550 and He II λ1640 emission lines from the Crab Nebula. Several interstellar absorption lines are detected along the line of sight to the pulsar. The Lyα absorption indicates a column density of (3.0+/-0.5)×1021 cm-2 of neutral hydrogen, which agrees well with our estimate of E(B-V)=0.52 mag. Other lines show no evidence of severe depletion of metals in atomic gas. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.

  • 307.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Selsing, J.
    Vreeswijk, P. M.
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Nyholm, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    The optical and NIR spectrum of the Crab pulsar with X-shooter2019Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 629, artikkel-id A140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. Pulsars are well studied all over the electromagnetic spectrum, and the Crab pulsar may be the most studied object in the sky. Nevertheless, a high-quality optical to near-infrared (NIR) spectrum of the Crab or any other pulsar has not been published to date.

    Aims. Obtaining a properly flux-calibrated spectrum enables us to measure the spectral index of the pulsar emission, without many of the caveats from previous studies. This was the main aim of this project, but in addition we could also detect absorption and emission features from the pulsar and nebula over an unprecedentedly wide wavelength range.

    Methods. A spectrum was obtained with the X-shooter spectrograph on the Very Large Telescope. Special care was given to the flux-calibration of these data.

    Results. A high signal-to-noise spectrum of the Crab pulsar was obtained from 300 nm to 2400 nm. The spectral index fit to this spectrum is flat with alpha(nu) = 0.16 +/- 0.07. For the emission lines we measured a maximum velocity of similar to 1600 km s(-1), whereas the absorption lines from the material between us and the pulsar is unresolved at the similar to 50 km s(-1) resolution. A number of diffuse interstellar bands and a few NIR emission lines that have previously not been reported from the Crab are highlighted.

  • 308.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Arcavi, I.
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). California Institute of Technology, USA.
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Burke, J.
    Cenko, S. B.
    Andersen, O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Andreoni, I.
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Blagorodova, N.
    Brink, T. G.
    Filippenko, A. V.
    Gal-Yam, A.
    Hiramatsu, D.
    Hosseinzadeh, G.
    Howell, D. A.
    de Jaeger, T.
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    McCully, C.
    Perley, D. A.
    Tartaglia, Leonardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Terreran, G.
    Valenti, S.
    Wang, X.
    Late-time observations of the extraordinary Type II supernova iPTF14hls2019Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 621, artikkel-id A30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims. We study iPTF14hls, a luminous and extraordinary long-lived Type II supernova, which lately has attracted much attention and disparate interpretation.

    Methods. We have presented new optical photometry that extends the light curves up to more than three years past discovery. We also obtained optical spectroscopy over this period, and furthermore present additional space-based observations using Swift and HST.

    Results. After an almost constant luminosity for hundreds of days, the later light curve of iPTF14hls finally fades and then displays a dramatic drop after about 1000 d, but the supernova is still visible at the latest epochs presented. The spectra have finally turned nebular, and our very last optical spectrum likely displays signatures from the deep and dense interior of the explosion. A high-resolution HST image highlights the complex environment of the explosion in this low-luminosity galaxy.

    Conclusions. We provide a large number of additional late-time observations of iPTF14hls, which are (and will continue to be) used to assess the many different interpretations for this intriguing object. In particular, the very late (+1000 d) steep decline of the optical light curve is difficult to reconcile with the proposed central engine models. The lack of very strong X-ray emission, and the emergence of intermediate-width emission lines including [S II] that we propose originate from dense, processed material in the core of the supernova ejecta, are also key observational tests for both existing and future models.

  • 309.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Perley, D.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, C.
    Kasliwal, M.
    Shin, K.
    Racine, B.
    Maximum luminosities of normal stripped-envelope supernovae are brighter than explosion models allow2022Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 657, artikkel-id A64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. Stripped-envelope supernovae (SE SNe) of Type Ib and Type Ic are thought to be the result of explosions of massive stars that have lost their outer envelopes. The favored explosion mechanism is via core-collapse, with the shock later revived by neutrino heating. However, there is an upper limit to the amount of radioactive Ni-56 that such models can accommodate. Recent studies in the literature point to a tension between the maximum luminosity from such simulations and the observations.

    Aims. We used a well-characterized sample of SE SNe from the Zwicky Transient Facility (ZTF) Bright Transient Survey (BTS) to scrutinize the observational caveats regarding estimates of the maximum luminosity (and thus the amount of ejected radioactive nickel) for the sample members.

    Methods. We employed the strict selection criteria for the BTS to collect a sample of spectroscopically classified normal Type Ibc SNe, for which we used the ZTF light curves to determine the maximum luminosity. We culled the sample further based on data quality, shape of the light curves, distances, and colors. Then we examined the uncertainties that may affect the measurements. The methodology of the sample construction based on this BTS sample can be used for other future investigations.

    Results. We analyzed the observational data, consisting of optical light curves and spectra, for the selected sub-samples. In total, we used 129 Type Ib or Type Ic BTS SNe with an initial rough luminosity distribution peaking at M-r = -17.61 +/- 0.72, and where 36% are apparently brighter than the theoretically predicted maximum brightness of M-r = -17.8. When we further culled this sample to ensure that the SNe are normal Type Ibc with good LC data within the Hubble flow, the sample of 94 objects gives M-r = -17.64 +/- 0.54. A main uncertainty in absolute magnitude determinations for SNe is the host galaxy extinction correction, but the reddened objects only get more luminous after corrections. If we simply exclude red objects, or those with unusual or uncertain colors, then we are left with 14 objects at M-r = -17.90 +/- 0.73, whereof a handful are most certainly brighter than the suggested theoretical limit. The main result of this study is thus that normal SNe Ibc do indeed reach luminosities above 10(426) erg s(-1), which is apparently in conflict with existing explosion models.

  • 310.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Henan Academy of Sciences, PR China.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Lundqvist, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    The broad-lined Type-Ic supernova SN 2022xxf and its extraordinary two-humped light curves I. Signatures of H/He-free interaction in the first four months2023Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 678, artikkel-id A209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on our study of the supernova (SN) 2022xxf based on observations obtained during the first four months of its evolution. The light curves (LCs) display two humps of similar maximum brightness separated by 75 days, unprecedented for a broad-lined (BL) Type Ic supernova (SN IcBL). SN 2022xxf is the most nearby SN IcBL to date (in NGC 3705, z = 0.0037, at a distance of about 20 Mpc). Optical and near-infrared photometry and spectroscopy were used to identify the energy source powering the LC. Nearly 50 epochs of high signal-to-noise ratio spectroscopy were obtained within 130 days, comprising an unparalleled dataset for a SN IcBL, and one of the best-sampled SN datasets to date. The global spectral appearance and evolution of SN 2022xxf points to typical SN Ic/IcBL, with broad features (up to ~14 000 km s−1) and a gradual transition from the photospheric to the nebular phase. However, narrow emission lines (corresponding to ~ 1000–2500 km s−1) are present in the spectra from the time of the second rise, suggesting slower-moving circumstellar material (CSM). These lines are subtle, in comparison to the typical strong narrow lines of CSM-interacting SNe, for example, Type IIn, Ibn, and Icn, but some are readily noticeable at late times, such as in Mg I λ5170 and [O I] λ5577. Unusually, the near-infrared spectra show narrow line peaks in a number of features formed by ions of O and Mg. We infer the presence of CSM that is free of H and He. We propose that the radiative energy from the ejecta-CSM interaction is a plausible explanation for the second LC hump. This interaction scenario is supported by the color evolution, which progresses to blue as the light curve evolves along the second hump, and by the slow second rise and subsequent rapid LC drop. SN 2022xxf may be related to an emerging number of CSM-interacting SNe Ic, which show slow, peculiar LCs, blue colors, and subtle CSM interaction lines. The progenitor stars of these SNe likely experienced an episode of mass loss consisting of H/He-free material shortly prior to explosion.

  • 311.
    Sollerman, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strotjohann, N. L.
    Jerkstrand, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Van Dyk, S. D.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Tel Aviv University, Israel.
    Brink, T. G.
    Bruch, R.
    De, K.
    Filippenko, A. V.
    Fremling, C.
    Patra, K. C.
    Perley, D.
    Yan, L.
    Yang, Y.
    Andreoni, I.
    Campbell, R.
    Coughlin, M.
    Kasliwal, M.
    Kim, Y. -L.
    Rigault, M.
    Shin, K.
    Tzanidakis, A.
    Ashley, M. C. B.
    Moore, A. M.
    Travouillon, T.
    The Type II supernova SN 2020jfo in M 61, implications for progenitor system, and explosion dynamics2021Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 655, artikkel-id A105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the discovery and extensive follow-up observations of SN 2020jfo, a Type IIP supernova (SN) in the nearby (14.5 Mpc) galaxy M 61. Optical light curves (LCs) and spectra from the Zwicky Transient Facility (ZTF), complemented with data from Swift/UVOT and near-infrared photometry is presented. These were used to model the 350-day duration bolometric light curve, which exhibits a relatively short (∼65 days) plateau. This implies a moderate ejecta mass (∼5 M⊙) at the time of explosion, whereas the deduced amount of ejected radioactive nickel is ∼0.025 M⊙. An extensive series of spectroscopy is presented, including spectropolarimetric observations. The nebular spectra are dominated by Hα, but also reveal emission lines from oxygen and calcium. Comparisons to synthetic nebular spectra indicate an initial progenitor mass of ∼12 M⊙. We also note the presence of stable nickel in the nebular spectrum, and SN 2020jfo joins a small group of SNe that have inferred super-solar Ni/Fe ratios. Several years of prediscovery data were examined, but no signs of precursor activity were found. Pre-explosion Hubble Space Telescope imaging reveals a probable progenitor star, detected only in the reddest band (MF814W ≈ −5.8) and it is fainter than expected for stars in the 10−15 M⊙ range. There is thus some tension between the LC analysis, the nebular spectral modeling, and the pre-explosion imaging. To compare and contrast, we present two additional core-collapse SNe monitored by the ZTF, which also have nebular Hα-dominated spectra. This illustrates how the absence or presence of an interaction with circumstellar material (CSM) affect both the LCs and in particular the nebular spectra. Type II SN 2020amv has a LC powered by CSM interaction, in particular after ∼40 days when the LC is bumpy and slowly evolving. The late-time spectra show strong Hα emission with a structure suggesting emission from a thin, dense shell. The evolution of the complex three-horn line profile is reminiscent of that observed for SN 1998S. Finally, SN 2020jfv has a poorly constrained early-time LC, but it is of interest because of the transition from a hydrogen-poor Type IIb to a Type IIn, where the nebular spectrum after the light-curve rebrightening is dominated by Hα, although with an intermediate line width.

  • 312. Soumagnac, Maayane T.
    et al.
    Ganot, Noam
    Irani, Ido
    Gal-yam, Avishay
    Ofek, Eran O.
    Waxman, Eli
    Morag, Jonathan
    Yaron, Ofer
    Schulze, Steve
    Yang, Yi
    Rubin, Adam
    Cenko, S. Bradley
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Perley, Daniel A.
    Fremling, Christoffer
    Nugent, Peter
    Neill, James D.
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bellm, Eric C.
    Bruch, Rachel J.
    Burruss, Rick
    Cunningham, Virginia
    Dekany, Richard
    Golkhou, V. Zach
    Graham, Matthew J.
    Kasliwal, Mansi M.
    Konidaris, Nicholas P.
    Kulkarni, Shrinivas R.
    Kupfer, Thomas
    Laher, Russ R.
    Masci, Frank J.
    Riddle, Reed
    Rigault, Mickael
    Rusholme, Ben
    van Roestel, Jan
    Zackay, Barak
    SN 2018fif: The Explosion of a Large Red Supergiant Discovered in Its Infancy by the Zwicky Transient Facility2020Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 902, nr 1, artikkel-id 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-cadence transient surveys are able to capture supernovae closer to their first light than ever before. Applying analytical models to such early emission, we can constrain the progenitor stars' properties. In this paper, we present observations of SN 2018fif (ZTF 18abokyfk). The supernova was discovered close to first light and monitored by the Zwicky Transient Facility (ZTF) and the Neil Gehrels Swift Observatory. Early spectroscopic observations suggest that the progenitor of SN 2018fif was surrounded by relatively small amounts of circumstellar material compared to all previous cases. This particularity, coupled with the high-cadence multiple-band coverage, makes it a good candidate to investigate using shock-cooling models. We employ the SOPRANOS code, an implementation of the model by Sapir & Waxman and its extension to early times by Morag et al. Compared with previous implementations, SOPRANOS has the advantage of including a careful account of the limited temporal validity domain of the shock-cooling model as well as allowing usage of the entirety of the early UV data. We find that the progenitor of SN 2018fif was a large red supergiant with a radius of R = 744.0(-128.0)(+183.0) R-circle dot and an ejected mass of M-ej = 9.3(-5.8)(+0.4) M-circle dot. Our model also gives information on the explosion epoch, the progenitor's inner structure, the shock velocity, and the extinction. The distribution of radii is double-peaked, with smaller radii corresponding to lower values of the extinction, earlier recombination times, and a better match to the early UV data. If these correlations persist in future objects, denser spectroscopic monitoring constraining the time of recombination, as well as accurate UV observations (e.g., with ULTRASAT), will help break the extinction/radius degeneracy and independently determine both.

  • 313. Soumagnac, Maayane T.
    et al.
    Ofek, Eran O.
    Liang, Jingyi
    Gal-yam, Avishay
    Nugent, Peter
    Yang, Yi
    Cenko, S. Bradley
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Perley, Daniel A.
    Andreoni, Igor
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Burdge, Kevin B.
    Bruch, Rachel J.
    De, Kishalay
    Dugas, Alison
    Fremling, Christoffer
    Graham, Melissa L.
    Hankins, Matthew J.
    Strotjohann, Nora Linn
    Moran, Shane
    Neill, James D.
    Schulze, Steve
    Shupe, David L.
    Sipőcz, Brigitta M.
    Taggart, Kirsty
    Tartaglia, Leonardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walters, Richard
    Yan, Lin
    Yao, Yuhan
    Yaron, Ofer
    Bellm, Eric C.
    Cannella, Chris
    Dekany, Richard
    Duev, Dmitry A.
    Feeney, Michael
    Frederick, Sara
    Graham, Matthew J.
    Laher, Russ R.
    Masci, Frank J.
    Kasliwal, Mansi M.
    Kowalski, Marek
    Kupfer, Thomas
    Miller, Adam A.
    Rigault, Mickael
    Rusholme, Ben
    Early Ultraviolet Observations of Type IIn Supernovae Constrain the Asphericity of Their Circumstellar Material2020Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 899, nr 1, artikkel-id 51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a survey of the early evolution of 12 Type IIn supernovae (SNe IIn) at ultraviolet and visible light wavelengths. We use this survey to constrain the geometry of the circumstellar material (CSM) surrounding SN IIn explosions, which may shed light on their progenitor diversity. In order to distinguish between aspherical and spherical CSM, we estimate the blackbody radius temporal evolution of the SNe IIn of our sample, following the method introduced by Soumagnac et al. We find that higher-luminosity objects tend to show evidence for aspherical CSM. Depending on whether this correlation is due to physical reasons or to some selection bias, we derive a lower limit between 35% and 66% for the fraction of SNe IIn showing evidence for aspherical CSM. This result suggests that asphericity of the CSM surrounding SNe IIn is common-consistent with data from resolved images of stars undergoing considerable mass loss. It should be taken into account for more realistic modeling of these events.

  • 314. Sparre, M.
    et al.
    Hartoog, O. E.
    Kruhler, T.
    Fynbo, J. P. U.
    Watson, D. J.
    Wiersema, K.
    D'Elia, V.
    Zafar, T.
    Afonso, P. M. J.
    Covino, S.
    Postigo, A. de Ugarte
    Flores, H.
    Goldoni, P.
    Greiner, J.
    Hjorth, J.
    Jakobsson, P.
    Kaper, L.
    Klose, S.
    Levan, A. J.
    Malesani, D.
    Milvang-Jensen, B.
    Nardini, M.
    Piranomonte, S.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sanchez-Ramirez, R.
    Schulze, S.
    Tanvir, N. R.
    Vergani, S. D.
    Wijers, R. A. M. J.
    THE METALLICITY AND DUST CONTENT OF A REDSHIFT 5 GAMMA-RAY BURST HOST GALAXY2014Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 785, nr 2, s. 150-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GRB host galaxy at z = 5.0. The host absorption system is a damped Ly alpha absorber with a very large neutral hydrogen column density of log N (H I)/cm(-2) = 22.30 +/- 0.06 and a metallicity of [S/H] = -1.70 +/- 0.10. It is the highest-redshift GRB with such a precise metallicity measurement. The presence of fine-structure lines confirms the z = 5.0 system as the GRB host galaxy and makes this the highest redshift where Fe II fine-structure lines have been detected. The afterglow is mildly reddened with A(V) = 0.11 +/- 0.04 mag, and the host galaxy has a DTM that is consistent with being equal to or lower than typical values in the Local Group.

  • 315. Sparre, M.
    et al.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fynbo, J. P. U.
    Malesani, D.
    Goldoni, P.
    Postigo, A. de Ugarte
    Covino, S.
    D'Elia, V.
    Flores, H.
    Hammer, F.
    Hjorth, J.
    Jakobsson, P.
    Kaper, L.
    Leloudas, G.
    Levan, A. J.
    Milvang-Jensen, B.
    Schulze, S.
    Tagliaferri, G.
    Tanvir, N. R.
    Watson, D. J.
    Wiersema, K.
    Wijers, R. A. M. J.
    SPECTROSCOPIC EVIDENCE FOR SN 2010ma ASSOCIATED WITH GRB 101219B2011Inngår i: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 735, nr 1, s. L24-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on the spectroscopic detection of supernova SN 2010ma associated with the long gamma-ray burst GRB 101219B. We observed the optical counterpart of the GRB on three nights with the X-shooter spectrograph at the Very Large Telescope. From weak absorption lines, we measure a redshift of z = 0.55. The first-epoch UV-near-infrared afterglow spectrum, taken 11.6 hr after the burst, is well fit by a power law consistent with the slope of the X-ray spectrum. The second-and third-epoch spectra (obtained 16.4 and 36.7 days after the burst), however, display clear bumps closely resembling those of the broad-lined type-Ic SN 1998bw if placed at z = 0.55. Apart from demonstrating that spectroscopic SN signatures can be observed for GRBs at these large distances, our discovery makes a step forward in establishing a general connection between GRBs and SNe. In fact, unlike most previous unambiguous GRB-associated SNe, GRB 101219B has a large gamma-ray energy (E(iso) = 4.2x10(51) erg), a bright afterglow, and obeys the Amati relation, thus being fully consistent with the cosmological population of GRBs.

  • 316. Spiro, S.
    et al.
    Pastorello, A.
    Pumo, M. L.
    Zampieri, L.
    Turatto, M.
    Smartt, S. J.
    Benetti, S.
    Cappellaro, E.
    Valenti, S.
    Agnoletto, I.
    Altavilla, G.
    Aoki, T.
    Brocato, E.
    Corsini, E. M.
    Di Cianno, A.
    Elias-Rosa, N.
    Hamuy, M.
    Enya, K.
    Fiaschi, M.
    Folatelli, G.
    Desidera, S.
    Harutyunyan, A.
    Howell, D. A.
    Kawka, A.
    Kobayashi, Y.
    Leibundgut, B.
    Minezaki, T.
    Navasardyan, H.
    Nomoto, K.
    Mattila, S.
    Pietrinferni, A.
    Pignata, G.
    Raimondo, G.
    Salvo, M.
    Schmidt, B. P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Spyromilio, J.
    Taubenberger, S.
    Valentini, G.
    Vennes, S.
    Yoshii, Y.
    Low luminosity Type II supernovae - II. Pointing towards moderate mass precursors2014Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 439, nr 3, s. 2873-2892Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present new data for five underluminous Type II-plateau supernovae (SNe IIP), namely SN 1999gn, SN 2002gd, SN 2003Z, SN 2004eg and SN 2006ov. This new sample of low-luminosity SNe IIP (LL SNe IIP) is analysed together with similar objects studied in the past. All of them show a flat light-curve plateau lasting about 100 d, an underluminous late-time exponential tail, intrinsic colours that are unusually red, and spectra showing prominent and narrow P Cygni lines. A velocity of the ejected material below 10(3) km s(-1) is inferred from measurements at the end of the plateau. The Ni-56 masses ejected in the explosion are very small (< 10(-2) M-circle dot). We investigate the correlations among Ni-56 mass, expansion velocity of the ejecta and absolute magnitude in the middle of the plateau, confirming the main findings of Hamuy, according to which events showing brighter plateau and larger expansion velocities are expected to produce more Ni-56. We propose that these faint objects represent the LL tail of a continuous distribution in parameters space of SNe IIP. The physical properties of the progenitors at the explosion are estimated through the hydrodynamical modelling of the observables for two representative events of this class, namely SN 2005cs and SN 2008in. We find that the majority of LL SNe IIP, and quite possibly all, originate in the core collapse of intermediate-mass stars, in the mass range 10-15 M-circle dot.

  • 317. Srinivasaragavan, G. P.
    et al.
    Sfaradi, I.
    Jencson, J.
    De, K.
    Horesh, A.
    Kasliwal, M. M.
    Tinyanont, S.
    Hankins, M.
    Schulze, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ashley, M. C. B.
    Graham, M. J.
    Karambelkar, V.
    Lau, R.
    Mahabal, A. A.
    Moore, A. M.
    Ofek, E. O.
    Sharma, Y.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Soon, J.
    Soria, R.
    Travouillon, T.
    Walters, R.
    PGIR 20eid (SN 2020qmp): A Type IIP Supernova at 15.6 Mpc discovered by the Palomar Gattini-IR survey2022Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 660, artikkel-id A138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims. We present a detailed analysis of SN 2020qmp, a nearby Type IIP core-collapse supernova (CCSN) that was discovered by the Palomar Gattini-IR survey in the galaxy UGC07125 (distance of approximate to 15.6 +/- 4 Mpc). We illustrate how the multiwavelength study of this event helps our general understanding of stellar progenitors and circumstellar medium (CSM) interactions in CCSNe. We highlight the importance of near-infrared (NIR) surveys for detections of supernovae in dusty environments.

    Methods. We analyze data from observations in various bands: radio, NIR, optical, and X-rays. We use optical and NIR data for a spectroscopic and spectro-polarimetric study of the supernova and to model its light curve (LC). We obtain an estimate of the zero-age main-sequence (ZAMS) progenitor mass from the luminosity of the [OI] doublet lines (lambda lambda 6300, 6364) normalized to the decay power of Co-56. We also independently estimate the explosion energy and ZAMS progenitor mass through hydrodynamical LC modeling. From radio and X-ray observations, we derive the mass-loss rate and microphysical parameters of the progenitor star, and we investigate possible deviations from energy equipartition of magnetic fields and electrons in a standard CSM interaction model. Finally, we simulate a sample of CCSNe with plausible distributions of brightness and extinction, within 40 Mpc, and test what fraction of the sample is detectable at peak light by NIR surveys versus optical surveys.

    Results. SN 2020qmp displays characteristic hydrogen lines in its optical spectra as well as a plateau in its optical LC, hallmarks of a Type IIP supernova. We do not detect linear polarization during the plateau phase, with a 3 sigma upper limit of 0.78%. Through hydrodynamical LC modeling and an analysis of its nebular spectra, we estimate a ZAMS progenitor mass of around 11.0 M-circle dot and an explosion energy of around 0.8x10(51) erg. We find that the spectral energy distribution cannot be explained by a simple CSM interaction model, assuming a constant shock velocity and a steady mass-loss rate. In particular, the excess X-ray luminosity compared with the synchrotron radio luminosity suggests deviations from equipartition. Finally, we demonstrate the advantages of NIR surveys over optical surveys for the detection of dust-obscured CCSNe in the local Universe. Specifically, our simulations show that the WideField Infrared Transient Explorer will detect up to 14 more CCSNe (out of the 75 expected in its footprint) within 40 Mpc over five years than would an optical survey equivalent to the Zwicky Transient Facility.

    Conclusions. We have determined or constrained the main properties of SN 2020qmp and its progenitor, highlighting the value of multiwavelength follow-up observations of nearby CCSNe. We have shown that forthcoming NIR surveys will enable us to improve constraints on the local CCSN rate by detecting obscured supernovae that would be missed by optical searches.

  • 318. Srinivasaragavan, Gokul P.
    et al.
    O'Connor, Brendan
    Cenko, S. Bradley
    Dittmann, Alexander J.
    Yang, Sheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Henan Academy of Sciences, Zhengzhou, Henan, People's Republic of China.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Anupama, G. C.
    Barway, Sudhanshu
    Bhalerao, Varun
    Kumar, Harsh
    Swain, Vishwajeet
    Hammerstein, Erica
    Holt, Isiah
    Anand, Shreya
    Andreoni, Igor
    Coughlin, Michael W.
    Dichiara, Simone
    Gal-Yam, Avishay
    Miller, M. Coleman
    Soon, Jaime
    Soria, Roberto
    Durbak, Joseph
    Gillanders, James H.
    Laha, Sibasish
    Moore, Anna M.
    Ragosta, Fabio
    Troja, Eleonora
    A Sensitive Search for Supernova Emission Associated with the Extremely Energetic and Nearby GRB 221009A2023Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 949, nr 2, artikkel-id L39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report observations of the optical counterpart of the long gamma-ray burst GRB 221009A. Due to the extreme rarity of being both nearby (z = 0.151) and highly energetic (E ( gamma,iso) >= 10(54) erg), GRB 221009A offers a unique opportunity to probe the connection between massive star core collapse and relativistic jet formation across a very broad range of gamma-ray properties. Adopting a phenomenological power-law model for the afterglow and host galaxy estimates from high-resolution Hubble Space Telescope imaging, we use Bayesian model comparison techniques to determine the likelihood of an associated supernova (SN) contributing excess flux to the optical light curve. Though not conclusive, we find moderate evidence (K (Bayes) = 10(1.2)) for the presence of an additional component arising from an associated SN, SN 2022xiw, and find that it must be substantially fainter (<67% as bright at the 99% confidence interval) than SN 1998bw. Given the large and uncertain line-of-sight extinction, we attempt to constrain the SN parameters (M (Ni), M (ej), and E (KE)) under several different assumptions with respect to the host galaxy's extinction. We find properties that are broadly consistent with previous GRB-associated SNe: M (Ni) = 0.05-0.25 M (circle dot), M (ej) = 3.5-11.1 M (circle dot), and E (KE) = (1.6-5.2) x 10(52) erg. We note that these properties are weakly constrained due to the faintness of the SN with respect to the afterglow and host emission, but we do find a robust upper limit on M (Ni) of M (Ni) < 0.36 M (circle dot). Given the tremendous range in isotropic gamma-ray energy release exhibited by GRBs (seven orders of magnitude), the SN emission appears to be decoupled from the central engine in these systems.

  • 319. Srinivasaragavan, Gokul P.
    et al.
    Swain, Vishwajeet
    O'Connor, Brendan
    Anand, Shreya
    Ahumada, Tomás
    Perley, Daniel
    Stein, Robert
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, Christoffer
    Cenko, S. Bradley
    Antier, S.
    Guessoum, Nidhal
    Hussenot-Desenonges, Thomas
    Hello, Patrice
    Lesage, Stephen
    Hammerstein, Erica
    Miller, M. Coleman
    Andreoni, Igor
    Bhalerao, Varun
    Bloom, Joshua S.
    Dutta, Anirban
    Gal-Yam, Avishay
    Hinds, K-Ryan
    Jaodand, Amruta
    Kasliwal, Mansi
    Kumar, Harsh
    Kutyrev, Alexander S.
    Ragosta, Fabio
    Ravi, Vikram
    Sharma, Kritti
    Singh Teja, Rishabh
    Yang, Sheng
    Anupama, G. C.
    Bellm, Eric C.
    Coughlin, Michael W.
    Mahabal, Ashish A.
    Masci, Frank J.
    Pathak, Utkarsh
    Purdum, Josiah
    Roberts, Oliver J.
    Smith, Roger
    Wold, Avery
    Characterizing the Ordinary Broad-line Type Ic SN 2023pel from the Energetic GRB 230812B2024Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 960, nr 2, artikkel-id L18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report observations of the optical counterpart of the long gamma-ray burst (GRB) GRB 230812B and its associated supernova (SN) SN 2023pel. The proximity (z = 0.36) and high energy (Eγ,iso ∼ 1053 erg) make it an important event to study as a probe of the connection between massive star core collapse and relativistic jet formation. With a phenomenological power-law model for the optical afterglow, we find a late-time flattening consistent with the presence of an associated SN. SN 2023pel has an absolute peak r-band magnitude of Mr = −19.46 ± 0.18 mag (about as bright as SN 1998bw) and evolves on quicker timescales. Using a radioactive heating model, we derive a nickel mass powering the SN of MNi = 0.38 ± 0.01 M and a peak bolometric luminosity of Lbol ∼ 1.3 × 1043 erg s−1. We confirm SN 2023pel's classification as a broad-line Type Ic SN with a spectrum taken 15.5 days after its peak in the r band and derive a photospheric expansion velocity of vph = 11,300 ± 1600 km s−1 at that phase. Extrapolating this velocity to the time of maximum light, we derive the ejecta mass Mej = 1.0 ± 0.6 M and kinetic energy EKE = 1.3 +3.3/-1.2 x 1051 erg. We find that GRB 230812B/SN 2023pel has SN properties that are mostly consistent with the overall GRB-SN population. The lack of correlations found in the GRB-SN population between SN brightness and Eγ,iso for their associated GRBs across a broad range of 7 orders of magnitude provides further evidence that the central engine powering the relativistic ejecta is not coupled to the SN powering mechanism in GRB-SN systems.

  • 320.
    Stanishev, Vallery
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Benetti, S
    Kotak, Rubina
    Pignata, G
    Navasardyan, H
    Mazzali, P
    Ahmanullah, Rahman
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Garavini, Gabriele
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Nobili, Serena
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Qiu, Y
    Elias-Rosa, N
    Ruiz-Lapuente, P
    Mendez, J
    Meikle, Peter
    Patat, F
    Pastorello, A
    Altavilla, G
    Gustafsson, M
    Harutyunyan, A
    Ijima, T
    Jakobsson, P
    Kichizhieva, M. V.
    Lundqvist, Peter
    Institutionen för astronomi.
    Mattila, Seppo
    Melinder, Jens
    Institutionen för astronomi.
    Pavlenko, E. P.
    Pavlyuk, N. N.
    Sollerman, Jesper
    Institutionen för astronomi.
    Tsvetkov, D. Yu.
    Turatto, M
    Hillebrandt, Wolfgang
    SN 2003du: 480 days in the life of a normal type Ia supernova2007Inngår i: Astronomy and Astrophysics, Vol. 469, nr 2, s. 645-661Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims.We present a study of the optical and near-infrared (NIR) properties of the Type Ia Supernova (SN Ia) 2003du.

    Methods: An extensive set of optical and NIR photometry and low-resolution long-slit spectra was obtained using a number of facilities. The observations started 13 days before B-band maximum light and continued for 480 days with exceptionally good time sampling. The optical photometry was calibrated through the S-correction technique.

    Results: The {UBVRIJHK} light curves and the color indices of SN 2003du closely resemble those of normal SNe Ia. SN 2003du reached a B-band maximum of 13.49 ± 0.02 mag on JD2 452 766.38 ± 0.5. We derive a B-band stretch parameter of 0.988 ±0.003, which corresponds to Δ m15=1.02 ±0.05, indicative of a SN Ia of standard luminosity. The reddening in the host galaxy was estimated by three methods, and was consistently found to be negligible. Using an updated calibration of the V and {JHK} absolute magnitudes of SNe Ia, we find a distance modulus μ=32.79±0.15 mag to the host galaxy, UGC 9391. We measure a peak {uvoir} bolometric luminosity of 1.35(±0.20)×1043 erg s-1 and Arnett's rule implies that M56Ni≃0.68 ±0.14 Mȯ of 56Ni was synthesized during the explosion. Modeling of the {uvoir} bolometric light curve also indicates M56Ni in the range 0.6-0.8 Mȯ. The spectral evolution of SN 2003du at both optical and NIR wavelengths also closely resembles normal SNe Ia. In particular, the Si II ratio at maximum R(Si II) = 0.22 ±0.02 and the time evolution of the blueshift velocities of the absorption line minima are typical. The pre-maximum spectra of SN 2003du showed conspicuous high-velocity features in the Ca II H&K doublet and infrared triplet, and possibly in Si II λ6355, lines. We compare the time evolution of the profiles of these lines with other well-observed SNe Ia and we suggest that the peculiar pre-maximum evolution of Si II λ6355 line in many SNe Ia is due to the presence of two blended absorption components.

  • 321. Starling, R. L. C.
    et al.
    Wiersema, K.
    Levan, A. J.
    Sakamoto, T.
    Bersier, D.
    Goldoni, P.
    Oates, S. R.
    Rowlinson, A.
    Campana, S.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tanvir, N. R.
    Malesani, D.
    Fynbo, J. P. U.
    Covino, S.
    D'Avanzo, P.
    O'Brien, P. T.
    Page, K. L.
    Osborne, J. P.
    Vergani, S. D.
    Barthelmy, S.
    Burrows, D. N.
    Cano, Z.
    Curran, P. A.
    De Pasquale, M.
    D'Elia, V.
    Evans, P. A.
    Flores, H.
    Fruchter, A. S.
    Garnavich, P.
    Gehrels, N.
    Gorosabel, J.
    Hjorth, J.
    Holland, S. T.
    van der Horst, A. J.
    Hurkett, C. P.
    Jakobsson, P.
    Kamble, A. P.
    Kouveliotou, C.
    Kuin, N. P. M.
    Kaper, L.
    Mazzali, P. A.
    Nugent, P. E.
    Pian, E.
    Stamatikos, M.
    Thoene, C. C.
    Woosley, S. E.
    Discovery of the nearby long, soft GRB 100316D with an associated supernova2011Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 411, nr 4, s. 2792-2803Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the Swift discovery of the nearby long, soft gamma-ray burst GRB 100316D, and the subsequent unveiling of its low-redshift host galaxy and associated supernova. We derive the redshift of the event to be z = 0.0591 +/- 0.0001 and provide accurate astrometry for the gamma-ray burst (GRB) supernova (SN). We study the extremely unusual prompt emission with time-resolved gamma-ray to X-ray spectroscopy and find that the spectrum is best modelled with a thermal component in addition to a synchrotron emission component with a low peak energy. The X-ray light curve has a remarkably shallow decay out to at least 800 s. The host is a bright, blue galaxy with a highly disturbed morphology and we use Gemini-South, Very Large Telescope and Hubble Space Telescope observations to measure some of the basic host galaxy properties. We compare and contrast the X-ray emission and host galaxy of GRB 100316D to a subsample of GRB-SNe. GRB 100316D is unlike the majority of GRB-SNe in its X-ray evolution, but resembles rather GRB 060218, and we find that these two events have remarkably similar high energy prompt emission properties. Comparison of the host galaxies of GRB-SNe demonstrates, however, that there is a great diversity in the environments in which GRB-SNe can be found. GRB 100316D is an important addition to the currently sparse sample of spectroscopically confirmed GRB-SNe, from which a better understanding of long GRB progenitors and the GRB-SN connection can be gleaned.

  • 322. Stein, Robert
    et al.
    Mahabal, Ashish
    Reusch, Simeon
    Graham, Matthew
    Kasliwal, Mansi M.
    Kowalski, Marek
    Gezari, Suvi
    Hammerstein, Erica
    Nakoneczny, Szymon J.
    Nicholl, Matt
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    van Velzen, Sjoert
    Yao, Yuhan
    Laher, Russ R.
    Rusholme, Ben
    tdescore: An Accurate Photometric Classifier for Tidal Disruption Events2024Inngår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 965, nr 2, artikkel-id L14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optical surveys have become increasingly adept at identifying candidate tidal disruption events (TDEs) in large numbers, but classifying these generally requires extensive spectroscopic resources. Here we present tdescore, a simple binary photometric classifier that is trained using a systematic census of ∼3000 nuclear transients from the Zwicky Transient Facility (ZTF). The sample is highly imbalanced, with TDEs representing ∼2% of the total. tdescore is nonetheless able to reject non-TDEs with 99.6% accuracy, yielding a sample of probable TDEs with recall of 77.5% for a precision of 80.2%. tdescore is thus substantially better than any available TDE photometric classifier scheme in the literature, with performance not far from spectroscopy as a method for classifying ZTF nuclear transients, despite relying solely on ZTF data and multiwavelength catalog cross matching. In a novel extension, we use "Shapley additive explanations" to provide a human-readable justification for each individual tdescore classification, enabling users to understand and form opinions about the underlying classifier reasoning. tdescore can serve as a model for photometric identification of TDEs with time-domain surveys, such as the upcoming Rubin observatory.

  • 323. Stein, Robert
    et al.
    Reusch, Simeon
    Franckowiak, Anna
    Kowalski, Marek
    Necker, Jannis
    Weimann, Sven
    Kasliwal, Mansi M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ahumada, Tomas
    Seoane, Pau Amaro
    Anand, Shreya
    Andreoni, Igor
    Bellm, Eric C.
    Bloom, Joshua S.
    Coughlin, Michael
    De, Kishalay
    Fremling, Christoffer
    Gezari, Suvi
    Graham, Matthew
    Groom, Steven L.
    Helou, George
    Kaplan, David L.
    Karambelkar, Viraj
    Kong, Albert K. H.
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lincetto, Massimiliano
    Mahabal, Ashish A.
    Masci, Frank J.
    Medford, Michael S.
    Morgan, Robert
    Nordin, Jakob
    Rodriguez, Hector
    Sharma, Yashvi
    van Santen, Jakob
    van Velzen, Sjoert
    Yan, Lin
    Neutrino follow-up with the Zwicky transient facility: results from the first 24 campaigns2023Inngår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 521, nr 4, s. 5046-5063Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Zwicky Transient Facility (ZTF) performs a systematic neutrino follow-up programme, searching for optical counterparts to high-energy neutrinos with dedicated Target-of-Opportunity (ToO) observations. Since first light in March 2018, ZTF has taken prompt observations for 24 high-quality neutrino alerts from the IceCube Neutrino Observatory, with a median latency of 12.2 h from initial neutrino detection. From two of these campaigns, we have already reported tidal disruption event (TDE) AT 2019dsg and likely TDE AT 2019fdr as probable counterparts, suggesting that TDEs contribute >7.8 per cent of the astrophysical neutrino flux. We here present the full results of our programme through to December 2021. No additional candidate neutrino sources were identified by our programme, allowing us to place the first constraints on the underlying optical luminosity function of astrophysical neutrino sources. Transients with optical absolutes magnitudes brighter that -21 can contribute no more than 87 per cent of the total, while transients brighter than -22 can contribute no more than 58 per cent of the total, neglecting the effect of extinction and assuming they follow the star formation rate. These are the first observational constraints on the neutrino emission of bright populations such as superluminous supernovae. None of the neutrinos were coincident with bright optical AGN flares comparable to that observed for TXS 0506+056/IC170922A, with such optical blazar flares producing no more than 26 per cent of the total neutrino flux. We highlight the outlook for electromagnetic neutrino follow-up programmes, including the expected potential for the Rubin Observatory.

  • 324. Stein, Robert
    et al.
    van Velzen, Sjoert
    Kowalski, Marek
    Franckowiak, Anna
    Gezari, Suvi
    Miller-Jones, James C. A.
    Frederick, Sara
    Sfaradi, Itai
    Bietenholz, Michael F.
    Horesh, Assaf
    Fender, Rob
    Garrappa, Simone
    Ahumada, Tomas
    Andreoni, Igor
    Belicki, Justin
    Bellm, Eric C.
    Bottcher, Markus
    Brinnel, Valery
    Burruss, Rick
    Cenko, S. Bradley
    Coughlin, Michael W.
    Cunningham, Virginia
    Drake, Andrew
    Farrar, Glennys R.
    Feeney, Michael
    Foley, Ryan J.
    Gal-Yam, Avishay
    Golkhou, V. Zach
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Graham, Matthew J.
    Hammerstein, Erica
    Helou, George
    Hung, Tiara
    Kasliwal, Mansi M.
    Kilpatrick, Charles D.
    Kong, Albert K. H.
    Kupfer, Thomas
    Laher, Russ R.
    Mahabal, Ashish A.
    Masci, Frank J.
    Necker, Jannis
    Nordin, Jakob
    Perley, Daniel A.
    Rigault, Mickael
    Reusch, Simeon
    Rodriguez, Hector
    Rojas-Bravo, César
    Rusholme, Ben
    Shupe, David L.
    Singer, Leo P.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Soumagnac, Maayane T.
    Stern, Daniel
    Taggart, Kirsty
    van Santen, Jakob
    Ward, Charlotte
    Woudt, Patrick
    Yao, Yuhan
    A tidal disruption event coincident with a high-energy neutrino2021Inngår i: Nature Astronomy, E-ISSN 2397-3366, nr 5, s. 510-518Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cosmic neutrinos provide a unique window into the otherwise hidden mechanism of particle acceleration in astrophysical objects. The IceCube Collaboration recently reported the likely association of one high-energy neutrino with a flare from the relativistic jet of an active galaxy pointed towards the Earth. However a combined analysis of many similar active galaxies revealed no excess from the broader population, leaving the vast majority of the cosmic neutrino flux unexplained. Here we present the likely association of a radio-emitting tidal disruption event, AT2019dsg, with a second high-energy neutrino. AT2019dsg was identified as part of our systematic search for optical counterparts to high-energy neutrinos with the Zwicky Transient Facility. The probability of finding any coincident radio-emitting tidal disruption event by chance is 0.5%, while the probability of finding one as bright in bolometric energy flux as AT2019dsg is 0.2%. Our electromagnetic observations can be explained through a multizone model, with radio analysis revealing a central engine, embedded in a UV photosphere, that powers an extended synchrotron-emitting outflow. This provides an ideal site for petaelectronvolt neutrino production. Assuming that the association is genuine, our observations suggest that tidal disruption events with mildly relativistic outflows contribute to the cosmic neutrino flux. The tidal disruption event AT2019dsg is probably associated with a high-energy neutrino, suggesting that such events can contribute to the cosmic neutrino flux. The electromagnetic emission is explained in terms of a central engine, a photosphere and an extended synchrotron-emitting outflow.

  • 325. Stritzinger, M. D.
    et al.
    Taddia, F.
    Holmbo, S.
    Baron, E.
    Contreras, C.
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Aarhus University, Denmark.
    Phillips, M. M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Suntzeff, N. B.
    Vinko, J.
    Ashall, C.
    Avila, C.
    Burns, C. R.
    Campillay, A.
    Castellon, S.
    Folatelli, G.
    Galbany, L.
    Hoeflich, P.
    Hsiao, E. Y.
    Marion, G. H.
    Morrell, N.
    Wheeler, J. C.
    The Carnegie Supernova Project II Early observations and progenitor constraints of the Type Ib supernova LSQ13abf2020Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 634, artikkel-id A21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Supernova LSQ13abf was discovered soon after explosion by the La Silla-QUEST Survey and then followed by the Carnegie Supernova Project II at its optical and near-IR wavelengths. Our analysis indicates that LSQ13abf was discovered within two days of explosion and its first approximate to 10 days of evolution reveal a B-band light curve with an abrupt drop in luminosity. Contemporaneously, the V-band light curve exhibits a rise towards a first peak and the r- and i-band light curves show no early peak.The early light-curve evolution of LSQ13abf is reminiscent of the post-explosion cooling phase observed in the Type Ib SN 2008D, and the similarity between the two objects extends over weeks. Spectroscopically, LSQ13abf also resembles SN 2008D, with P Cygni Hei features that strengthen over several weeks. Spectral energy distributions are constructed from the broad-bandphotometry, a UVOIR light curve is constructed by fitting black-body (BB) functions, and the underlying BB-temperature and BB-radius profiles are estimated. Explosion parameters are estimated by simultaneously fitting an Arnett model to the UVOIR light curve and the velocity evolution derived from spectral features, and an in addition to a post-shock breakout cooling model to the first two epochs of the bolometric evolution. This combined model suggests an explosion energy of 1.27 +/- 0.23 x 10(51) ergs, in addition to a relatively high ejecta mass of 5.94 +/- 1.10 M-circle dot, a Ni-56 mass of 0.16 +/- 0.02 M-circle dot, and a progenitor-star radius of 28.0 +/- 7.5 R-circle dot. The ejecta mass suggests the origins of LSQ13abf lie with a >25 M-circle dot zero-age-main-sequence mass progenitor and its estimated radius is three times larger compared to the result obtained from the same analysis applied to observations of SN 2008D, and nine times larger compared to SN 1999ex. Alternatively, a comparison of hydrodynamical simulations of greater than or similar to 20-25 M-circle dot zero-age-main-sequence progenitors that evolve to pre-supernova envelope masses of less than or similar to 10 M-circle dot and extended (similar to 100 R-circle dot) envelopes also broadly match the observations of LSQ13abf.

  • 326. Stritzinger, M. D.
    et al.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Burns, C. R.
    Phillips, M. M.
    Bersten, M.
    Contreras, C.
    Folatelli, G.
    Holmbo, S.
    Hsiao, E. Y.
    Hoeflich, P.
    Leloudas, G.
    Morrell, N.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Suntzeff, N. B.
    The Carnegie Supernova Project I: Methods to estimate host-galaxy reddening of stripped-envelope supernovae2018Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 609, artikkel-id A135Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We aim to improve upon contemporary methods to estimate host-galaxy reddening of stripped-envelope (SE) supernovae (SNe). To this end the Carnegie Supernova Project (CSP-I) SE SN photometry data release, consisting of nearly three dozen objects, is used to identify a minimally reddened sub-sample for each traditionally defined spectroscopic sub-type (i.e., SNe IIb, SNe Ib, SNe Ic). Inspection of the optical and near-infrared (NIR) colors and color evolution of the minimally reddened sub-samples reveals a high degree of homogeneity, particularly between 0 d to +20 d relative to B-band maximum. This motivated the construction of intrinsic color-curve templates, which when compared to the colors of reddened SE SNe, yields an entire suite of optical and NIR color excess measurements. Comparison of optical/optical vs. optical/NIR color excess measurements indicates the majority of the CSP-I SE SNe suffer relatively low amounts of reddening (i.e., E(B - V)(host) < 0.20 mag) and we find evidence for different R-host(V) values among di ff erent SE SN. Fitting the color excess measurements of the seven most reddened (i. e., E(B - V)(host) > 0.20 mag) objects with the Fitzpatrick (1999, PASP, 111, 63) reddening law model provides robust estimates of the host visual-extinction A(host)(V) and R-host(V). In the case of the SE SNe with relatively low amounts of reddening, a preferred value of R-host(V) is adopted for each sub-type, resulting in estimates of A(V)(host) through Fitzpatrick (1999) reddening law model fits to the observed color excess measurements. Our analysis suggests SE SNe reside in galaxies characterized by a range of dust properties. We also find evidence that SNe Ic are more likely to occur in regions characterized by larger A(V)(host) values compared to SNe IIb/Ib and they also tend to suffer more extinction. The later finding is consistent with work in the literature suggesting SNe Ic tend to occur in regions of on-going star formation.

  • 327. Stritzinger, M
    et al.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Late-time emission of type Ia supernovae: optical and near-infrared observations of SN 2001el2007Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, Vol. 470, nr 1, s. L1-L4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aims.To elucidate the nature of the late-phase emission of the normal type Ia supernova SN 2001el.

    Methods: We present optical and near-infrared light curves of SN 2001el from 310 to 445 days past maximum light, obtained with the Very Large Telescope.

    Results: The late-time optical (UBVRI) light curves decay in a nearly linear fashion with decay time scales of 1.43±0.14, 1.43±0.06, 1.48±0.06, 1.45±0.07, and 1.03±0.07 magnitudes (per hundred days) in the U, B, V, R, and I bands, respectively. In contrast, in the near-infrared ({JHK}_s) bands the time evolution of the flux appears to be nearly constant at these epochs. We measure decline rates (per hundred days) of 0.19±0.10 and 0.17±0.11 magnitudes in the J and H bands, respectively. We construct a UVOIR light curve, and find that the late-time luminosity has a decay time scale nearly consistent with complete depostion of positron kinetic energy.

    Conclusions: The late-time light curves of the normal type Ia SN 2001el demonstrate the increased importance of the near-infrared contribution. This was previously observed in the peculiar SN 2000cx, and the results for SN 2001el thus ensure that the conclusions previously based on a single peculiar event are applicable to normal type Ia supernovae. The measured late-time UVOIR decline rate suggests that a majority of the positrons are trapped within the ejecta. This result does not favor the prediction of a weak and/or radially combed magnetic field configuration.

  • 328. Stritzinger, Maximilian
    et al.
    Mazzali, Paolo
    Phillips, Mark M.
    Immler, Stefan
    Soderberg, Alicia
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Boldt, Luis
    Braithwaite, Jonathan
    Brown, Peter
    Burns, Christopher R.
    Contreras, Carlos
    Covarrubias, Ricardo
    Folatelli, Gastón
    Freedman, Wendy L.
    González, Sergio
    Hamuy, Mario
    Krzeminski, Wojtek
    Madore, Barry F.
    Milne, Peter
    Morrell, Nidia
    Persson, S. E.
    Roth, Miguel
    Smith, Mathew
    Suntzeff, Nicholas B.
    The He-Rich Core-Collapse Supernova 2007Y: Observations from X-Ray to Radio Wavelengths2009Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 696, nr 1, s. 713-728Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A detailed study spanning approximately a year has been conducted on the Type Ib supernova (SN) 2007Y. Imaging was obtained from X-ray to radio wavelengths, and a comprehensive set of multi-band (w2m2w1u'g'r'i'UBVYJHKs ) light curves and optical spectroscopy is presented. A virtually complete bolometric light curve is derived, from which we infer a 56Ni mass of 0.06 M sun. The early spectrum strongly resembles SN 2005bf and exhibits high-velocity features of Ca II and Hα during late epochs the spectrum shows evidence of an ejecta-wind interaction. Nebular emission lines have similar widths and exhibit profiles that indicate a lack of major asymmetry in the ejecta. Late phase spectra are modeled with a non-LTE code, from which we find 56Ni, O, and total-ejecta masses (excluding He) to be 0.06, 0.2, and 0.42 M sun, respectively, below 4500 km s-1. The 56Ni mass confirms results obtained from the bolometric light curve. The oxygen abundance suggests that the progenitor was most likely a ≈3.3 M sun He core star that evolved from a zero-age-main-sequence mass of 10-13 M sun. The explosion energy is determined to be ≈1050 erg, and the mass-loss rate of the progenitor is constrained from X-ray and radio observations to be lsim10-6 M sun yr-1. SN 2007Y is among the least energetic normal Type Ib SNe ever studied. Partly based on observations collected at the European Southern Observatory, La Silla and Paranal Observatories, Chile (ESO Programme 078.D-0048 and 380.D-0272).

  • 329.
    Stritzinger, Maximilian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Aarhus University, Denmark.
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fox, Ori D.
    Morrell, Nidia
    Phillips, M. M.
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Anderson, J. P.
    Boldt, Luis
    Brown, Peter J.
    Campillay, Abdo
    Castellon, Sergio
    Contreras, Carlos
    Folatelli, Gastón
    Habergham, S. M.
    Hamuy, Mario
    Hjorth, Jens
    James, Phil A.
    Krzeminski, Wojtek
    Mattila, Seppo
    Persson, Sven E.
    Roth, Miguel
    Multi-wavelength Observations of the Enduring Type IIn Supernovae 2005ip and 2006jd2012Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 756, nr 2, artikkel-id 173Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an observational study of the Type IIn supernovae (SNe IIn) 2005ip and 2006jd. Broadband UV, optical, and near-IR photometry, and visual-wavelength spectroscopy of SN 2005ip complement and extend upon published observations to 6.5 years past discovery. Our observations of SN 2006jd extend from UV to mid-infrared wavelengths, and like SN 2005ip, are compared to reported X-ray measurements to understand the nature of the progenitor. Both objects display a number of similarities with the 1988Z-like subclass of SN IIn including (1) remarkably similar early- and late-phase optical spectra, (2) a variety of high-ionization coronal lines, (3) long-duration optical and near-IR emission, and (4) evidence of cold and warm dust components. However, diversity is apparent, including an unprecedented late-time r-band excess in SN 2006jd. The observed differences are attributed to differences between the mass-loss history of the progenitor stars. We conclude that the progenitor of SN 2006jd likely experienced a significant mass-loss event during its pre-SN evolution akin to the great 19th century eruption of η Carinae. Contrarily, as advocated by Smith et al., the circumstellar environment of SN 2005ip is found to be more consistent with a clumpy wind progenitor.

  • 330. Strotjohann, Nora L.
    et al.
    Ofek, Eran O.
    Gal-Yam, Avishay
    Bruch, Rachel
    Schulze, Steve
    Shaviv, Nir
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Filippenko, Alexei V.
    Yaron, Ofer
    Fremling, Christoffer
    Nordin, Jakob
    Kool, Erik C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Perley, Dan A.
    Ho, Anna Y. Q.
    Yang, Yi
    Yao, Yuhan
    Soumagnac, Maayane T.
    Graham, Melissa L.
    Barbarino, Cristina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tartaglia, Leonardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). INAF—Osservatorio Astronomico di Padova, Italy.
    De, Kishalay
    Goldstein, Daniel A.
    Cook, David O.
    Brink, Thomas G.
    Taggart, Kirsty
    Yan, Lin
    Lunnan, Ragnhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kasliwal, Mansi
    Kulkarni, Shri R.
    Nugent, Peter E.
    Masci, Frank J.
    Rosnet, Philippe
    Adams, Scott M.
    Andreoni, Igor
    Bagdasaryan, Ashot
    Bellm, Eric C.
    Burdge, Kevin
    Duev, Dmitry A.
    Dugas, Alison
    Frederick, Sara
    Goldwasser, Samantha
    Hankins, Matthew
    Irani, Ido
    Karambelkar, Viraj
    Kupfer, Thomas
    Liang, Jingyi
    Neill, James D.
    Porter, Michael
    Riddle, Reed L.
    Sharma, Yashvi
    Short, Phil
    Taddia, Francesco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tzanidakis, Anastasios
    Roestel, Jan van
    Walters, Richard
    Zhuang, Zhuyun
    Bright, Months-long Stellar Outbursts Announce the Explosion of Interaction-powered Supernovae2021Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 907, nr 2, artikkel-id 99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Interaction-powered supernovae (SNe) explode within an optically thick circumstellar medium (CSM) that could be ejected during eruptive events. To identify and characterize such pre-explosion outbursts, we produce forced-photometry light curves for 196 interacting SNe, mostly of Type IIn, detected by the Zwicky Transient Facility between early 2018 and 2020 June. Extensive tests demonstrate that we only expect a few false detections among the 70,000 analyzed pre-explosion images after applying quality cuts and bias corrections. We detect precursor eruptions prior to 18 Type IIn SNe and prior to the Type Ibn SN 2019uo. Precursors become brighter and more frequent in the last months before the SN and month-long outbursts brighter than magnitude -13 occur prior to 25% (5-69%, 95% confidence range) of all Type IIn SNe within the final three months before the explosion. With radiative energies of up to 10(49) erg, precursors could eject similar to 1 M of material. Nevertheless, SNe with detected precursors are not significantly more luminous than other SNe IIn, and the characteristic narrow hydrogen lines in their spectra typically originate from earlier, undetected mass-loss events. The long precursor durations require ongoing energy injection, and they could, for example, be powered by interaction or by a continuum-driven wind. Instabilities during the neon- and oxygen-burning phases are predicted to launch precursors in the final years to months before the explosion; however, the brightest precursor is 100 times more energetic than anticipated.

  • 331. Strotjohann, Nora L.
    et al.
    Ofek, Eran O.
    Gal-Yam, Avishay
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Chen, Ping
    Yaron, Ofer
    Zackay, Barak
    Rehemtulla, Nabeel
    Gris, Phillipe
    Masci, Frank J.
    Rusholme, Ben
    Purdum, Josiah
    Search for Supernova Progenitor Stars with ZTF and LSST2024Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 960, nr 1, artikkel-id 72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The direct detection of core-collapse supernova (SN) progenitor stars is a powerful way of probing the last stages of stellar evolution. However, detections in archival Hubble Space Telescope images are limited to about one detection per year. Here, we explore whether we can increase the detection rate by using data from ground-based wide-field surveys. Due to crowding and atmospheric blurring, progenitor stars can typically not be identified in preexplosion images alone. Instead, we combine many pre-SN and late-time images to search for the disappearance of the progenitor star. As a proof of concept, we implement our search of ZTF data. For a few hundred images, we achieve limiting magnitudes of ∼23 mag in the g and r bands. However, no progenitor stars or long-lived outbursts are detected for 29 SNe within z ≤ 0.01, and the ZTF limits are typically several magnitudes less constraining than detected progenitors in the literature. Next, we estimate progenitor detection rates for the Legacy Survey of Space and Time (LSST) with the Vera C. Rubin telescope by simulating a population of nearby SNe. The background from bright host galaxies reduces the nominal LSST sensitivity by, on average, 0.4 mag. Over the 10 yr survey, we expect the detection of ∼50 red supergiant progenitors and several yellow and blue supergiants. The progenitors of Type Ib and Ic SNe will be detectable if they are brighter than −4.7 or −4.0 mag in the LSST i band, respectively. In addition, we expect the detection of hundreds of pre-SN outbursts depending on their brightness and duration.

  • 332. Strotjohann, Nora L.
    et al.
    Ofek, Eran O.
    Gal-Yam, Avishay
    Sullivan, Mark
    Kulkarni, Shrinivas R.
    Shaviv, Nir J.
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kasliwal, Mansi M.
    Nugent, Peter E.
    Cao, Yi
    Arcavi, Iair
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Filippenko, Alexei V.
    Yaron, Ofer
    Laher, Russ
    Surace, Jason
    SEARCH FOR PRECURSOR ERUPTIONS AMONG TYPE IIB SUPERNOVAE2015Inngår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 811, nr 2, artikkel-id 117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The progenitor stars of several Type IIb supernovae (SNe) show indications of extended hydrogen envelopes. These envelopes might be the outcome of luminous energetic pre-explosion events, so-called precursor eruptions. We use the Palomar Transient Factory (PTF) pre-explosion observations of a sample of 27 nearby SNe IIb to look for such precursors during the final years prior to the SN explosion. No precursors are found when combining the observations in 15-day bins, and we calculate the absolute-magnitude-dependent upper limit on the precursor rate. At the 90% confidence level, SNe IIb have on average <0.86 precursors as bright as an absolute R-band magnitude of -14 in the final 3.5 years before the explosion and <0.56 events over the final year. In contrast, precursors among SNe IIn have a greater than or similar to 5 times higher rate. The kinetic energy required to unbind a low-mass stellar envelope is comparable to the radiated energy of a few-weeks-long precursor that would be detectable for the closest SNe in our sample. Therefore, mass ejections, if they are common in such SNe, are radiatively inefficient or have durations longer than months. Indeed, when using 60-day bins, a faint precursor candidate is detected prior to SN 2012cs (similar to 2% false-alarm probability). We also report the detection of the progenitor of SN 2011dh that does not show detectable variability over the final two years before the explosion. The suggested progenitor of SN 2012P is still present, and hence is likely a compact star cluster or an unrelated object.

  • 333. Szkody, Paula
    et al.
    Loohuis, Claire Olde
    Koplitz, Brad
    van Roestel, Jan
    Dicenzo, Brooke
    Ho, Anna Y. Q.
    Hillenbrand, Lynne A.
    Bellm, Eric C.
    Dekany, Richard
    Drake, Andrew J.
    Duev, Dmitry A.
    Graham, Matthew J.
    Kasliwal, Mansi M.
    Mahabal, Ashish A.
    Masci, Frank J.
    Neill, James D.
    Riddle, Reed
    Rusholme, Benjamin
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walters, Richard
    Cataclysmic Variables in the Second Year of the Zwicky Transient Facility2021Inngår i: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 162, nr 3, artikkel-id 94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using a filter in the GROWTH Marshal based on color and the amplitude and timescale of variability, we have identified 372 objects as known or candidate cataclysmic variables (CVs) during the second year of the operation of the Zwicky Transient Facility. From the available difference imaging data, we found that 93 are previously confirmed CVs and 279 are strong candidates. Spectra of four of the candidates confirm them as CVs by the presence of Balmer emission lines, while one of the four has prominent He ii lines indicative of containing a magnetic white dwarf. Gaia EDR3 parallaxes are available for 154 of these systems, resulting in distances from 108–2096 pc and absolute magnitudes in the range of 7.5–15.0, with the largest number of candidates between 10.5 and 12.5. The total numbers are 21% higher than from the previous year of the survey with a greater number of distances available but a smaller percentage of systems close to the Galactic plane. Comparison of these findings with a machine-learning method of searching all the light curves reveals large differences in each data set related to the parameters involved in the search process.

  • 334.
    Taddia, Francesco
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fremling, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Corsi, A.
    Gal-Yam, A.
    Karamehmetoglu, Emir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lunnan, R.
    Bue, B.
    Ergon, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kasliwal, M.
    Vreeswijk, P. M.
    Wozniak, P. R.
    iPTF15dtg: a double-peaked Type Ic supernova from a massive progenitor2016Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 592, artikkel-id A89Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Context. Type Ic supernovae (SNe Ic) arise from the core-collapse of H-(and He-) poor stars, which could either be single Wolf-Rayet (WR) stars or lower-mass stars stripped of their envelope by a companion. Their light curves are radioactively powered and usually show a fast rise to peak (similar to 10-15 d), without any early (in the first few days) emission bumps (with the exception of broad-lined SNe Ic) as sometimes seen for other types of stripped-envelope SNe (e.g., Type IIb SN 1993J and Type Ib SN 2008D). Aims. We have studied iPTF15dtg, a spectroscopically normal SN Ic with an early excess in the optical light curves followed by a long (similar to 30 d) rise to the main peak. It is the first spectroscopically-normal double-peaked SN Ic to be observed. Our aim is to determine the properties of this explosion and of its progenitor star. Methods. Optical photometry and spectroscopy of iPTF15dtg was obtained with multiple telescopes. The resulting light curves and spectral sequence are analyzed and modeled with hydrodynamical and analytical models, with particular focus on the early emission. Results. iPTF15dtg is a slow rising SN Ic, similar to SN 2011bm. Hydrodynamical modeling of the bolometric properties reveals a large ejecta mass (similar to 10 M-circle dot) and strong Ni-56 mixing. The luminous early emission can be reproduced if we account for the presence of an extended (greater than or similar to 500 R-circle dot), low-mass (greater than or similar to 0.045 M-circle dot) envelope around the progenitor star. Alternative scenarios for the early peak, such as the interaction with a companion, a shock-breakout (SBO) cooling tail from the progenitor surface, or a magnetar-driven SBO are not favored. Conclusions. The large ejecta mass and the presence of H-and He-free extended material around the star suggest that the progenitor of iPTF15dtg was a massive (greater than or similar to 35 M-circle dot) WR star that experienced strong mass loss.

  • 335.
    Taddia, Francesco
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moquist, Patrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sollerman, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rubin, A.
    Leloudas, G.
    Gal-Yam, A.
    Arcavi, I.
    Cao, Y.
    Filippenko, A. V.
    Graham, M. L.
    Mazzali, P. A.
    Nugent, P. E.
    Pan, Y. -C.
    Silverman, J. M.
    Xu, D.
    Yaron, O.
    Metallicity from Type II supernovae from the (i)PTF2016Inngår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 587, artikkel-id L7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Type IIP supernovae (SNe IIP) have recently been proposed as metallicity (Z) probes. The spectral models of Dessart et al. (2014, MNRAS, 440, 1856) showed that the pseudo-equivalent width of Fe lambda 5018 (pEW(5018)) during the plateau phase depends on the primordial Z, but there was a paucity of SNe IIP exhibiting pEW(5018) that were compatible with Z < 0.4 Z(circle dot). This lack might be due to some physical property of the SN II population or to the fact that those SNe have been discovered in luminous, metal-rich targeted galaxies. Here we use SN II observations from the untargeted (intermediate) Palomar Transient Factory [(i)PTF] survey, aiming to investigate the pEW5018 distribution of this SN population and, in particular, to look for the presence of SNe II at lower Z. We perform pEW(5018) measurements on the spectra of a sample of 39 (i) PTF SNe II, selected to have well-constrained explosion epochs and light-curve properties. Based on t