Suchergebnisse

Full list of authors: Dhillon, V. S.; Bezawada, N.; Black, M.; Dixon, S. D.; Gamble, T.; Gao, X.; Henry, D. M.; Kerry, P.; Littlefair, S. P.; Lunney, D. W.; Marsh, T. R.; Miller, C.; Parsons, S. G.; Ashley, R. P.; Breedt, E.; Brown, A.; Dyer, M. J.; Green, M. J.; Pelisoli, I.; Sahman, D. I. Wild, J.; Ives, D. J.; Mehrgan, L.; Stegmeier, J.; Dubbeldam, C. M.; Morris, T. J.; Osborn, J.; Wilson, R. W.; Casares, J.; Muñoz-Darias, T.; Pallé, E.; Rodríguez-Gil, P.; Shahbaz, T.; Torres, M. A. P.; de Ugarte Postigo, A.; Cabrera-Lavers, A.; Corradi, R. L. M.; Domínguez, R. D.; García-Alvarez, D. ; HiPERCAM is a portable, quintuple-beam optical imager that saw first light on the 10.4-m Gran Telescopio Canarias (GTC) in 2018. The instrument uses re-imaging optics and four dichroic beamsplitters to record us, gs, rs, is, zs (320-1060 nm) images simultaneously on its five CCD cameras, each of 3.1-arcmin (diagonal) field of view. The detectors in HiPERCAM are frame-transfer devices cooled thermo-electrically to 183 K, thereby allowing both long-exposure, deep imaging of faint targets, as well as high-speed (over 1000 windowed frames per second) imaging of rapidly varying targets. A comparison-star pick-off system in the telescope focal plane increases the effective field of view to 6.7 arcmin for differential photometry. Combining HiPERCAM with the world's largest optical telescope enables the detection of astronomical sources to gs ∼23 in 1 s and gs ∼28 in 1 h. In this paper, we describe the scientific motivation behind HiPERCAM, present its design, report on its measured performance, and outline some planned enhancements. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. ; HiPERCAM was funded by the European Research Council under the European Union's Seventh Framework Programme (FP/20072013) under ERC-2013-ADG GrantAgreement no. 340040 (HiPERCAM), with additional funding for operations and enhancements provided by the Science and Technology Facilities Council (STFC). This paper is based on observations made with the Gran Telescopio Canarias, installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. SGP acknowledges the support of an STFC Ernest Rutherford Fellowship. PR-G and TMD acknowledge support from the State Research Agency (AEI) of the Spanish Ministry of Science, Innovation and Universities (MCIU), and the European Regional Development Fund (FEDER) under grant AYA2017-83383-P. MAPT and TM-D acknowledge support via Ram ' on y Cajal Fellowships RYC-2015-17854 and RYC-201518148. ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed

Full list of authors: Melandri, A.; Izzo, L. ; Pian, E.; Malesani, D. B.; Della Valle, M.; Rossi, A.; D'Avanzo, P.; Guetta, D.; Mazzali, P. A.; Benetti, S.; Masetti, N.; Palazzi, E.; Savaglio, S.; Amati, L.; Antonelli, L. A.; Ashall, C.; Bernardini, M. G.; Campana, S.; Carini, R.; Covino, S.; D'Elia, V.; de Ugarte Postigo, A.; De Pasquale, M.; Filippenko, A. V.; Fruchter, A. S.; Fynbo, J. P. U.; Giunta, A.; Hartmann, D. H.; Jakobsson, P.; Japelj, J.; Jonker, P. G.; Kann, D. A.; Lamb, G. P.; Levan, A. J.; Martin-Carrillo, A.; Møller, P.; Piranomonte, S.; Pugliese, G.; Salvaterra, R.; Schulze, S.; Starling, R. L. C.; Stella, L.; Tagliaferri, G.; Tanvir, N.; Watson, D. ; We observed GRB 190114C (redshift z = 0.4245), the first gamma-ray burst (GRB) ever detected at TeV energies, at optical and near-infrared wavelengths with several ground-based telescopes and the Hubble Space Telescope, with the primary goal of studying its underlying supernova, SN 2019jrj. The monitoring spanned the time interval between 1.3 and 370 days after the burst, in the observer frame. We find that the afterglow emission can be modelled with a forward shock propagating in a uniform medium modified by time-variable extinction along the line of sight. A jet break could be present after 7 rest-frame days, and accordingly the maximum luminosity of the underlying supernova (SN) ranges between that of stripped-envelope core-collapse SNe of intermediate luminosity and that of the luminous GRB-associated SN 2013dx. The observed spectral absorption lines of SN 2019jrj are not as broad as in classical GRB SNe and are instead more similar to those of less-luminous core-collapse SNe. Taking the broad-lined stripped-envelope core-collapse SN 2004aw as an analogue, we tentatively derive the basic physical properties of SN 2019jrj. We discuss the possibility that a fraction of the TeV emission of this source might have had a hadronic origin and estimate the expected high-energy neutrino detection level with IceCube. © ESO 2022. ; A. M., M. G. B., P. D. A., S. C., and G. T. acknowledge support from ASI grant I/004/11/5. P. D. A., M. D. V., E. Pa., S. Sa., and S. P. acknowledge support from PRIN-MIUR 2017 (grant 20179ZF5KS). L. I. was supported by the VILLUM FONDEN (project numbers 16599 and 25501). D. B. M. acknowledges support from research grant 19054 from VILLUM FONDEN. A. V. F.'s research is supported by the Christopher R. Redlich Fund, the Miller Institute for Basic Research in Science (in which he is a Senior Miller Fellow), and many individual donors. D. A. K. acknowledges support from Spanish National Research Project RTI2018-098104-JI00 (GRBPhot). D. W. is supported by Independent Research Fund Denmark grant DFF-7014-00017. The Cosmic Dawn Center is supported by the Danish National Research Foundation under grant 140. A. R. acknowledges support from the project Supporto Arizona and Italia. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, representing OSU, University of Notre Dame, University of Minnesota, and University of Virginia. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed

Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. T.P. acknowledges support from NASA under the Swift GI grant 1619152, the Tess GI grant G03267, from the NYU Center for Cosmology and Particle Physics, from a 19 Washington Square North Award awarded to M.M, and in part by a grant from the New York University Research Challenge FundProgram. M.M. and the SNYU group have been supported by the NSF CAREER award AST-1352405, by the NSF award AST1413260, and by a Humboldt Faculty Fellowship. M.M. is grateful for her sabbatical stay supported by the Center for Computational Astrophysics at the Flatiron institute and for the hospitality of the Max-Planck Institute for Astronomy, Heidelberg, during which some of this work was accomplished. K.B. acknowledges financial support from the Ministerio de Economia y Competitividad through the Spanish grant BES2014-069767. K.B., C.T. and A.d.U.P. acknowledge support from the Spanish research project AYA2017-89384-P. C.T. acknowledges support from funding associated to a Ramon y Cajal fellowship RyC-2012-09984. A.d.U.P. acknowledges support from funding associated to a Ramon y Cajal fellowship RyC-2012-09975. L.I. acknowledges support from funding associated to a Juan de la Cierva Incorporacion fellowship IJCI-2016-30940. D.A.K. acknowledges support from the Spanish research projects AYA 2014-58381-P, AYA201789384-P, from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153, and from Spanish National Project research project RTI2018-098104-J-I00 (GRBPhot). J.V. and his research group at Konkoly Observatory is supported by the "Transient Astrophysical Objects" GINOP 2.3.2-15-2016-00033 project of the National Research, Development and Innovation Office (NKFIH), Hungary, funded by the European Union. K.V. and L.K. thank the financial support from the National Research, Development and Innovation Office (NKFIH), Hungary, under grants NKFI-K-131508 and NKFI-KH-130526. A.B. and K.V. are supported by the Lendulet program grant LP2018-7/2019 of the Hungarian Academy of Sciences. T.N.D. also acknowledges the support of the Hungarian OTKA grant No. 119993. The work of X.W. was funded by the National Science Foundation of China (NSFC grants 12033003, 11633002, and 11761141001), the Major State Basic Research Development Program (grant No. 2016YFA0400803), and the Scholar Program of Beijing Academy of Science and Technology (DZ:BS202002). L.G. was funded by the European Union's Horizon 2020 research and innovation program under the Marie SklodowskaCurie grant agreement No. 839090. This work has been partially supported by the Spanish grant PGC2018-095317-BC21 within the European Funds for Regional Development (FEDER). R.G.B. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through grant AYA2016-77846-P and from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709). These observations made use of the LCO network. D.A.H., C.P., D.H., and J.B. are supported by NSF Grant AST-1911225 and NASA Grant 80NSSC19k1639. ; In the last decade a number of rapidly evolving transients have been discovered that are not easily explained by traditional supernova models. We present optical and UV data on one such object, SN 2018gep, that displayed a fast rise with a mostly featureless blue continuum around peak, and evolved to develop broad features typical of an SN Ic-bl while retaining significant amounts of blue flux throughout its observations. This blue excess is most evident in its near-UV flux, which is over 4 mag brighter than other stripped-envelope supernovae, and is still visible in optical g-r colors. Its fast rise time of t (rise,V ) = 5.6 +/- 0.5 days puts it squarely in the emerging class of Fast Evolving Luminous Transients, or Fast Blue Optical Transients. With a peak absolute magnitude of M ( v ) = -19.53 +/- 0.23 mag it is on the extreme end of both the rise time and peak magnitude distribution for SNe Ic-bl. These observations are consistent with a simple SN Ic-bl model that has an additional form of energy injection at early times that drives the observed rapid, blue rise. We show that SN 2018gep and the literature SN iPTF16asu have similar photometric and spectroscopic properties and that they overall share many similarities with both SNe Ic-bl and Fast Evolving Transients. Based on our SN 2018gep host galaxy data we derive a number of properties, and we show that the derived host galaxy properties for both SN 2018gep and iPTF16asu are consistent with the SNe Ic-bl and gamma-ray burst/supernova sample while being on the extreme edge of the observed Fast Evolving Transient sample. ; W.M. Keck Foundation ; NASA under the Swift GI grant 1619152 ; Tess GI grant G03267 ; NYU Center for Cosmology and Particle Physics ; New York University Research Challenge FundProgram ; National Science Foundation (NSF) NSF - Office of the Director (OD) AST-1352405 National Science Foundation (NSF) AST-1911225 AST-1413260 ; Humboldt Faculty Fellowship ; Center for Computational Astrophysics at the Flatiron institute ; Spanish Government BES2014-069767 RyC-2012-09975 RyC-2012-09984 ; Juan de la Cierva Incorporacion fellowship IJCI-2015-26153 IJCI-2016-30940 ; "Transient Astrophysical Objects" project of the National Research, Development and Innovation Office (NKFIH), Hungary - European Union GINOP 2.3.2-15-2016-00033 ; National Research, Development & Innovation Office (NRDIO) - Hungary NKFI-K-131508 NKFI-KH-130526 ; Hungarian Academy of Sciences LP2018-7/2019 ; Orszagos Tudomanyos Kutatasi Alapprogramok (OTKA) 119993 ; National Natural Science Foundation of China (NSFC) 12033003 11633002 11761141001 ; National Basic Research Program of China 2016YFA0400803 ; Scholar Program of Beijing Academy of Science and Technology DZ:BS202002 ; European Commission 839090 PGC2018-095317-BC21 ; Spanish Ministry of Economy and Competitiveness AYA2016-77846-P ; State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award SEV-2017-0709 ; National Aeronautics & Space Administration (NASA) 80NSSC19k1639 ; 19 Washington Square North Award AYA 2014-58381-P AYA201789384-P RTI2018-098104-J-I00 AYA2017-89384-P

Full list of authors: Christensen, L.; Vergani, S. D.; Schulze, S.; Annau, N.; Selsing, J.; Fynbo, J. P. U.; de Ugarte Postigo, A.; Cañameras, R.; Lopez, S.; Passi, D.; Cortés-Zuleta, P.; Ellison, S. L.; D'Odorico, V.; Becker, G.; Berg, T. A. M.; Cano, Z.; Covino, S.; Cupani, G.; D'Elia, V.; Goldoni, P. Gomboc, A.; Hammer, F.; Heintz, K. E.; Jakobsson, P.; Japelj, J.; Kaper, L.; Malesani, D.; Møller, P.; Petitjean, P.; Pugliese, V.; Sánchez-Ramírez, R.; Tanvir, N. R.; Thöne, C. C.; Vestergaard, M.; Wiersema, K.; Worseck, G. ; Previous studies have shown that the incidence rate of intervening strong Mgii absorbers towards gamma-ray bursts (GRBs) were a factor of 2-4 higher than towards quasars. Exploring the similar sized and uniformly selected legacy data sets XQ-100 and XSGRB, each consisting of 100 quasar and 81 GRB afterglow spectra obtained with a single instrument (VLT/X-shooter), we demonstrate that there is no disagreement in the number density of strong Mgii absorbers with rest-frame equivalent widths W r > 1 Å towards GRBs and quasars in the redshift range 0:1 . z . 5. With large and similar sample sizes, and path length coverages of Δz = 57:8 and 254.4 for GRBs and quasars, respectively, the incidences of intervening absorbers are consistent within 1σ uncertainty levels at all redshifts. For absorbers at z < 2:3; the incidence towards GRBs is a factor of 1.5± 0.4 higher than the expected number of strong Mgii absorbers in Sloan Digital Sky Survey (SDSS) quasar spectra, while for quasar absorbers observed with X-shooter we find an excess factor of 1.4 ± 0.2 relative to SDSS quasars. Conversely, the incidence rates agree at all redshifts with reported high-spectralresolution quasar data, and no excess is found. The only remaining discrepancy in incidences is between SDSS Mgii catalogues and high-spectral-resolution studies. The rest-frame equivalent-width distribution also agrees to within 1σ uncertainty levels between the GRB and quasar samples. Intervening strong Mgii absorbers towards GRBs are therefore neither unusually frequent, nor unusually strong. © ESO 2017. ; L.C. and R.C. are supported by YDUN grant DFF 4090-00079. S.D.V. is supported by the French National Research Agency (ANR) under contract ANR-16-CE31-0003 BEaPro. S.L. has been supported by FONDECYT grant number 1140838 and partially by PFB-06 CATA. A.d.U.P. and C.T. acknowledge support from Ramon y Cajal fellowships, and with RSR a BBVA Foundation Grant for Researchers and Cultural Creators, and the Spanish Ministry of Economy and Competitiveness through project AYA2014-58381-P. G.B. acknowledges support from the National Science Foundation through grant AST-1615814. Z.C. acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2014-21669 and from the Spanish research project AYA2014-58381-P. P.J. and K.E.H. acknowledge support by a Project Grant (162948-051) from The Icelandic Research Fund. J.J. acknowledges support from NOVA and NWO-FAPESP grant for advanced instrumentation in astronomy. R.S.R. acknowledges support from ASI (Italian Space Agency) through the Contract No. 2015-046-R.0 and from European Union Horizon 2020 Programme under the AHEAD project (grant agreement No. 654215). M.V. gratefully acknowledges financial support from the Danish Council for Independent Research via grant no. DFF 4002-00275.

Tanvir, N.R. et. al. ; We report the discovery and monitoring of the near-infrared counterpart (AT2017gfo) of a binary neutron-star merger event detected as a gravitational wave source by Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo (GW170817) and as a short gamma-ray burst by Fermi Gamma-ray Burst Monitor (GBM) and Integral SPI-ACS (GRB 170817A). The evolution of the transient light is consistent with predictions for the behavior of a >kilonova/macronova> powered by the radioactive decay of massive neutron-rich nuclides created via r-process nucleosynthesis in the neutron-star ejecta. In particular, evidence for this scenario is found from broad features seen in Hubble Space Telescope infrared spectroscopy, similar to those predicted for lanthanide-dominated ejecta, and the much slower evolution in the near-infrared k-band compared to the optical. This indicates that the late-time light is dominated by high-opacity lanthanide-rich ejecta, suggesting nucleosynthesis to the third r-process peak (atomic masses A ≈ 195). This discovery confirms that neutron-star mergers produce kilo-/macronovae and that they are at least a major - if not the dominant - site of rapid neutron capture nucleosynthesis in the universe. ; A.J.L., D.S., and J.D.L. acknowledge support from STFC via grant ST/P000495/1. N.R.T. and A.J.L. have received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement No. 725246, TEDE, Levan). Ad.U.P., C.T., Z.C., and D.A.K. acknowledge support from the Spanish project AYA 2014-58381-P. Z.C. also acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2014-21669, and D.A.K. from Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. J.H. is supported by a VILLUM FONDEN Investigator grant (project number 16599). P.D.A., S.C., and A.M. acknowledge support from the ASI grant I/004/11/3. S.R. has been supported by the Swedish Research Council (VR) under grant No. 2016-03657_3, by the Swedish National Space Board under grant No. Dnr. 107/16, and by the research environment grant >Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT)> funded by the Swedish Research council (VR) under Dnr 2016-06012. ; Peer Reviewed

We report on multi-band observations of the transient source Swift J0840.7-3516, which was detected in outburst in 2020 February by the Neil Gehrels Swift Observatory. The outburst episode lasted just ∼5 days, during which the X-ray luminosity quickly decreased from LX ≈ 3 × 1037 d102 erg s-1 at peak down to LX ≈ 5 × 1033 d102 erg s-1 in quiescence (0.3-10 keV; d10 is the distance to the source in units of 10 kpc). Such x display--inline-block" style="background: var(--highlight-yellow); color: inherit;">a marked and rapid decrease in the flux was also registered at UV and optical wavelengths. In outburst, the source showed considerable aperiodic variability in the X-rays on timescales as short as x display--inline-block" style="background: var(--highlight-yellow); color: inherit;">a few seconds. The spectrum of the source in the energy range 0.3-20 keV was well described by x display--inline-block" style="background: var(--highlight-yellow); color: inherit;">a thermal, blackbody-like, component plus x display--inline-block" style="background: var(--highlight-yellow); color: inherit;">a non-thermal, power law-like, component and it softened considerably as the source returned to quiescence. The spectrum of the optical counterpart in quiescence showed broad emission features mainly associated with ionised carbon and oxygen, superposed on x display--inline-block" style="background: var(--highlight-yellow); color: inherit;">a blue continuum. No evidence for bright continuum radio emission was found in quiescence. We discuss possible scenarios for the nature of this source and show that the observed phenomenology points to x display--inline-block" style="background: var(--highlight-yellow); color: inherit;">a transient ultra-compact X-ray binary system. © ESO 2021. ; This research is based on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias in the island of La Palma, under Director's Discretionary Time (code GTC2020-142). The data were obtained with OSIRIS, built by a Consortium led by the Instituto de Astrofísica de Canarias in collaboration with the Instituto de Astronomía of the Universidad Autónoma de México. OSIRIS was funded by GRANTECAN and the National Plan of Astronomy and Astrophysics of the Spanish Government. We are indebted to Antonio Cabrera and the GTC staff for their efforts in performing the GTC observations. The NuSTAR mission is a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory and funded by NASA. The NICER mission operates on the International Space Station and is funded by NASA. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the traditional owners of the ATCA observatory site. This research made use of: the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC) and the California Institute of Technology; software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory; IRAF, distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation; APLpy (Robitaille & Bressert 2012), an open-source plotting package for Python hosted at https://aplpy.github.io/; and Astropy (Astropy Collaboration 2013, 2018), a community-developed core Python package for Astronomy. We also made use of the following software: CASA (McMullin et al. 2007), HEASOFT v. 6.28, HENDRICS v. 5.1 (Bachetti 2018), XSPEC v. 12.11.1 (Arnaud 1996). FCZ and AB are supported by Juan de la Cierva fellowships. FCZ, AB and NR are supported by the ERC Consolidator Grant 'MAGNESIA' (nr. 817661) and acknowledge funding from grants SGR2017-1383 and PGC2018-095512-BI00. AdUP acknowledges funding from a Ramón y Cajal fellowship (RyC-2012-09975). TDR acknowledges financial contribution from the agreement ASI-INAF n.2017-14-H.0. We thank support from the COST Action 'PHAROS' (CA 16124). ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (SEV-2017-0709). ; Peer reviewed

Publisher's version (útgefin grein) ; We present here a survey of high-ionization absorption lines in the afterglow spectra of long-duration gamma-ray bursts (GRBs) obtained with the VLT/X-shooter spectrograph. Our main goal is to investigate the circumburst medium in the natal regions of GRBs. Our primary focus is on the N Vλλ 1238, 1242 line transitions, but we also discuss other high-ionization lines such as O VI, C IV, and Si IV. We find no correlation between the column density of N V and the neutral gas properties such as metallicity, H I column density, and dust depletion; however, the relative velocity of N V, typically a blueshift with respect to the neutral gas, is found to be correlated with the column density of H I. This may be explained if the N V gas is part of an H II region hosting the GRB, where the region's expansion is confined by dense, neutral gas in the GRB's host galaxy. We find tentative evidence (at 2σ significance) that the X-ray derived column density, NH, X, may be correlated with the column density of N V, which would indicate that both measurements are sensitive to the column density of the gas located in the vicinity of the GRB. We investigate the scenario where N V (and also O VI) is produced by recombination after the corresponding atoms have been stripped entirely of their electrons by the initial prompt emission, in contrast to previous models where highly ionized gas is produced by photoionization from the GRB afterglow. ; KEH and PJ acknowledge support by a Project Grant (162948–051) from The Icelandic Research Fund. JK acknowledges financial support from the Danish Council for Independent Research (EU-FP7 under the Marie-Curie grant agreement no. 600207) with reference DFF–MOBILEX–5051–00115. JJ acknowledges support from NOVA and NWO-FAPESP grant for advanced instrumentation in astronomy. AG acknowledges the financial support from the Slovenian Research Agency (research core funding no. P1-0031 and project grant no. J1-8136). AdUP, CCT, and ZC acknowledge support from the Spanish Ministry of Economy and Competitivity under grant number AYA 2014-58381-P. AdUP and CCT acknowledge support from Ramon y Cajal fellowships (RyC-2012-09975 and RyC-2012-09984). AdUP acknowledges support from a grant from the BBVA foundation for researchers and cultural creators. ZC acknowledges support from the Juan de la Cierva Incorporación fellowship IJCI-2014-21669 and from the Spanish research project AYA 2014-58381-P. RS-R acknowledges support from ASI (Italian Space Agency) through the contract no. 2015-046-R.0 and from European Union Horizon 2020 Programme under the AHEAD project (grant agreement no. 654215). ; Peer Reviewed

We report on multicolor photometry of long GRB080603B afterglow from BOOTES-1B and BOOTES-2. The optical afterglow has already been reported to present a break in the optical lightcurve at 0.12 ± 0.2 days after the trigger. We construct the lightcurve and the spectral energy distribution and discuss the nature of the afterglow.

The hosts of long duration gamma-ray bursts (GRBs) are predominantly starburst galaxies at subsolar metallicity. At redshifts z < 1, this implies that most of them are low-mass galaxies similar to the populations of blue compact dwarfs and dwarf irregulars. What triggers the massive star-formation needed for producing a GRB progenitor is still largely unknown, as are the resolved gas properties and kinematics of these galaxies and their formation history. Here we present a sample of six spatially resolved GRB hosts at z < 0.3 observed with 3D spectroscopy at high spectral resolution (R = 8000-13 000) using FLAMES/VLT. We analyzed the resolved gas kinematics of the full sample and the abundances in a subsample with strong enough emission lines. Only two galaxies show a regular disk-like rotation field, another two are dispersion-dominated, and the remaining ones have two narrow emission components associated with different parts of the galaxy but no regular rotation field, which might indicate a recent merger. All galaxies show evidence for broad components underlying the main emission peak with σ of 50-110 km s-1. This broad component is more metal-rich than the narrow components, it is blueshifted in most cases, and it follows a different velocity structure. We find a weak correlation between the star-formation rate and the width of the broad component, its flux compared to the narrow component, and the maximum outflow velocity of the gas, but we do not find any correlation with the star-formation density, metallicity or stellar mass. We hence associate this broad component with a metal-rich outflow from star-forming regions in the host. The GRB is not located in the brightest region of the host, but is always associated with some star-forming region showing a clear wind component. Our study shows the great potential of 3D spectroscopy to study the star-formation processes and history in galaxies hosting extreme transients, the need for high signal-To-noise, and the perils using unresolved or only partially resolved data for these kinds of studies. © ESO 2021. ; CT and AdUP acknowledge support from AYA2017-89384-P, CT and AdUP also from a Ramón y Cajal fellowships RyC-2012-09984 and RyC-2012-09975, LI from a Juan de la Cierva Integración fellowship IJCI-2016-30940. DAK acknowledges support from the Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). JFAF acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. SDV acknowledges support from the French National Research Agency (ANR) under contract ANR-16-CE31-0003. LC is supported by YDUN grant DFF 4090-00079. Ground based observations were collected at the VLT under program 092.D-0389(A). ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed

We present a pilot search of CO emission in three H2-absorbing, long-duration gamma-ray burst (GRB) host galaxies at z ∼ 2-3. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to target the CO(3 - 2) emission line and report nondetections for all three hosts. These are used to place limits on the host molecular gas masses, assuming a metallicity-dependent CO-to-H2 conversion factor (αCO). We find, Mmol < 3.5 × 1010M⊙ (GRB 080607), Mmol < 4.7 × 1011M⊙ (GRB 120815A), and Mmol [removed]1 with M∗ < 1010M⊙. To better quantify this we develop a simple approach to estimate the relevant αCO factor based only on the redshift and stellar mass of individual galaxies. The elevated conversion factors will make these galaxies appear CO-'dark' and difficult to detect in emission, as is the case for the majority of GRB hosts. GRB spectroscopy thus offers a complementary approach to identify low-metallicity, star-forming galaxies with abundant molecular gas reservoirs at high redshifts that are otherwise missed by current ALMA surveys. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. ; KEH and PJ acknowledge support by a Project Grant (162948-051) from The Icelandic Research Fund. MN acknowledges support from ERC Advanced grant 740246 (Cosmic Gas). JPUF thanks the Carlsberg Foundation for support. The Cosmic DAWN Center is funded by the DNRF. PN and JKK acknowledge support from the French Agence Nationale de la Recherche under grant ANR 17-CE31-001101/project `HIH2' (PI: Noterdaeme). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2019.1.00407.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed

We present the extensive follow-up campaign on the afterglow of GRB 110715A at 17 different wavelengths, from X-ray to radio bands, starting 81 s after the burst and extending up to 74 d later. We performed for the first time a GRB afterglow observation with the ALMA observatory. We find that the afterglow of GRB 110715A is very bright at optical and radio wavelengths. We use the optical and near-infrared spectroscopy to provide further information about the progenitor's environment and its host galaxy. The spectrum shows weak absorption features at a redshift z = 0.8225, which reveal a host-galaxy environment with low ionization, column density, and dynamical activity. Late deep imaging shows a very faint galaxy, consistent with the spectroscopic results. The broad-band afterglow emission is modelled with synchrotron radiation using a numerical algorithm and we determine the best-fitting parameters using Bayesian inference in order to constrain the physical parameters of the jet and the medium in which the relativistic shock propagates. We fitted our data with a variety of models, including different density profiles and energy injections. Although the general behaviour can be roughly described by these models, none of them are able to fully explain all data points simultaneously. GRB 110715A shows the complexity of reproducing extensive multiwavelength broad-band afterglow observations, and the need of good sampling in wavelength and time and more complex models to accurately constrain the physics of GRB afterglows. ; RSR is grateful to SEPE for financial support while finishing this work and his PhD thesis. RSR, SRO, AJCT, YDH, SJ, and JCT acknowledge the financial support of the Spanish Government projects AYA 2009- 14000-C03-01 and AYA 2012-39727-C03-01. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project No. CE110001020. AdUP and CT acknowledge support from Ramon´ y Cajal fellowships and from the Spanish research project AYA 2014-58381. JJ acknowledges financial contribution from the grant PRIN MIUR 2012 201278X4FL 002 'The Intergalactic Medium as a probe of the growth of cosmic structures'. DAK acknowledges the financial support by MPE Garching and TLS Tautenburg. Part of the funding for GROND (both hardware as well as personnel) was generously granted from the Leibniz-Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). PS and TK acknowledges support through the Sofja Kovalevskaja Award to P. Schady from the Alexander von Humboldt Foundation of Germany. AU is grateful for travel funding support through the Max-Planck Inst. for Extraterrestrial Physics. SK and ANG acknowledge support by DFG grant Kl 766/16-1. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Facilities: This publication is based on data acquired with the Atacama Pathfinder Experiment (APEX) under program 087.F- 9301(A). This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00001.E. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. This publication is based on data acquired with the VLT/Xshooter under program 087.A-0055(C), as well as with VLT/FORS2 under program 091.A-0703(A). ; Peer-reviewed ; Publisher Version

We present here a survey of high-ionization absorption lines in the afterglow spectra of longduration gamma-ray bursts (GRBs) obtained with the VLT/X-shooter spectrograph. Our main goal is to investigate the circumburst medium in the natal regions of GRBs. Our primary focus is on the Nλλ 1238, 1242 line transitions, but we also discuss other high-ionization lines such as OVI, CIV, and SiIV. We find no correlation between the column density of N and the neutral gas properties such as metallicity, H column density, and dust depletion; however, the relative velocity of N, typically a blueshift with respect to the neutral gas, is found to be correlated with the column density of H. This may be explained if the N gas is part of an H region hosting the GRB, where the region's expansion is confined by dense, neutral gas in the GRB's host galaxy. We find tentative evidence (at 2σ significance) that the X-ray derived column density, N, may be correlated with the column density of N, which would indicate that both measurements are sensitive to the column density of the gas located in the vicinity of the GRB. We investigate the scenario where N (and also O) is produced by recombination after the corresponding atoms have been stripped entirely of their electrons by the initial prompt emission, in contrast to previous models where highly ionized gas is produced by photoionization from the GRB afterglow.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. ; We would like to thank the referee for a clear and thorough report, which greatly improved the presentation of the results in the paper. We also wish to thank K. Wiersema and P. Moller for enlightening discussions. KEH and PJ acknowledge support by a Project Grant (162948-051) from The Icelandic Research Fund. JK acknowledges financial support from the Danish Council for Independent Research (EU-FP7 under the Marie-Curie grant agreement no. 600207) with reference DFF-MOBILEX-5051-00115. JJ acknowledges support from NOVA and NWO-FAPESP grant for advanced instrumentation in astronomy. AG acknowledges the financial support from the Slovenian Research Agency (research core funding no. P1-0031 and project grant no. J1-8136). AdUP, CCT, and ZC acknowledge support from the Spanish Ministry of Economy and Competitivity under grant number AYA 2014-58381-P. AdUP and CCT acknowledge support from Ramon y Cajal fellowships (RyC-2012-09975 and RyC-2012-09984). AdUP acknowledges support from a grant from the BBVA foundation for researchers and cultural creators. ZC acknowledges support from the Juan de la Cierva Incorporacion fellowship IJCI-2014-21669 and from the Spanish research project AYA 2014-58381-P. RS-R acknowledges support from ASI (Italian Space Agency) through the contract no. 2015-046-R.0 and from European Union Horizon 2020 Programme under the AHEAD project (grant agreement no. 654215).

We present a comprehensive study of the relations between gas kinematics, metallicity and stellar mass in a sample of 82 gamma-ray burst (GRB)-selected galaxies using absorption and emission methods. We find the velocity widths of both emission and absorption profiles to be a proxy of stellar mass. We also investigate the velocity-metallicity correlation and its evolution with redshift. Using 33 GRB hosts with measured stellar mass and metallicity, we study the mass-metallicity relation for GRB host galaxies in a stellarmass range of 10-10M and a redshift range of z~0.3-3.4. TheGRB-selected galaxies appear to track themass-metallicity relation of star-forming galaxies but with an offset of 0.15 towards lower metallicities. This offset is comparable with the average error bar on the metallicity measurements of the GRB sample and also the scatter on the mass-metallicity relation of the general population. It is hard to decide whether this relatively small offset is due to systematic effects or the intrinsic nature of GRB hosts. We also investigate the possibility of using absorption-line metallicity measurements of GRB hosts to study the mass-metallicity relation at high redshifts. Our analysis shows that the metallicity measurements from absorption methods can significantly differ from emission metallicities and assuming identical measurements from the two methods may result in erroneous conclusions.© 2018 The Author(s). ; MA would like to specially thank Thomas Kruhler for very helpful discussions and also for providing stellar mass measurement prior to publication. MA also thanks Roberto Maiolino, Richard Ellis, Sambit Roychowdhury, Claudia Lagos, Jens Hjorth and Bernd Husemann for helpful discussions. We acknowledge the financial support from UnivEarthS Labex programme at Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013)/ERC Grant agreement no. EGGS-278202. AdUP acknowledges support from the Spanish research project AYA 2014-58381-P, a Ramon y Cajal fellowship and a 2016 BBVA Foundation Grant for Researchers and Cultural Creators.

Context. Unusual stellar explosions represent an opportunity to learn about both stellar and galaxy evolution. Mapping the atomic gas in host galaxies of such transients can lead to an understanding of the conditions that trigger them. Aims. We provide resolved atomic gas observations of the host galaxy, CGCG137-068, of the unusual and poorly understood transient AT 2018cow, which we obtained in searching for clues to understand its nature. We test whether it is consistent with a recent inflow of atomic gas from the intergalactic medium, as suggested for host galaxies of gamma-ray bursts (GRBs) and some supernovae (SNe). Methods. We observed the HI hyperfine structure line of the AT 2018cow host with the Giant Metrewave Radio Telescope. Results. There is no unusual atomic gas concentration near the position of AT 2018cow. The gas distribution is much more regular than the distributions of GRB/SN hosts. The AT 2018cow host has an atomic gas mass lower by 0.24 dex than predicted from its star formation rate (SFR) and is at the lower edge of the galaxy main sequence. In the continuum we detected the emission of AT 2018cow and of a star-forming region in the north-eastern part of the bar (away from AT 2018cow). This region hosts a third of the galaxy's SFR. Conclusions. The absence of atomic gas concentration close to AT 2018cow, along with a normal SFR and regular HI velocity field, sets CGCG137-068 apart from GRB/SN hosts studied in HI. The environment of AT 2018cow therefore suggests that its progenitor may not have been a massive star. Our findings are consistent with an origin of the transient that does not require a connection between its progenitor and gas concentration or inflow: an exploding low-mass star, a tidal disruption event, a merger of white dwarfs, or a merger between a neutron star and a giant star. We interpret the recently reported atomic gas ring in CGCG 137-068 as a result of internal processes connected with gravitational resonances caused by the bar.© ESO 2019. ; M.J.M. acknowledges the support of the National Science Centre, Poland, through the POLONEZ grant 2015/19/P/ST9/04010 and SONATA BIS grant 2018/30/E/ST9/00208; this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665778. P.K. is supported by the BMBF project 05A17PC2 for D-MeerKAT J.H. was supported by a VILLUM FONDEN Investigator grant (project number 16599). D.A.K. acknowledges support from the Juan de la Cierva Incorporación fellowship IJCI-2015-26153. A.d.U.P. and C.C.T. acknowledge support from Ramón y Cajal fellowships (RyC-2012-09975 and RyC-2012-09984). D.A.K., A.d.U.P., and C.C.T. acknowledge support from the Spanish research project AYA2017-89384-P. L.K.H. acknowledges funding from the INAF PRIN-SKA program 1.05.01.88.04. The Cosmic Dawn Center is funded by the DNRF. R.L. acknowledges support from the grant EMR/2016/007127 from the Dept. of Science and Technology, India. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 679627; project name FORNAX; PI Paolo Serra). ; Peer Reviewed

Context. Unusual stellar explosions represent an opportunity to learn about both stellar and galaxy evolution. Mapping the atomic gas in host galaxies of such transients can lead to an understanding of the conditions that trigger them. Aims. We provide resolved atomic gas observations of the host galaxy, CGCG137-068, of the unusual and poorly understood transient AT 2018cow, which we obtained in searching for clues to understand its nature. We test whether it is consistent with a recent inflow of atomic gas from the intergalactic medium, as suggested for host galaxies of gamma-ray bursts (GRBs) and some supernovae (SNe). Methods. We observed the HI hyperfine structure line of the AT 2018cow host with the Giant Metrewave Radio Telescope. Results. There is no unusual atomic gas concentration near the position of AT 2018cow. The gas distribution is much more regular than the distributions of GRB/SN hosts. The AT 2018cow host has an atomic gas mass lower by 0.24 dex than predicted from its star formation rate (SFR) and is at the lower edge of the galaxy main sequence. In the continuum we detected the emission of AT 2018cow and of a star-forming region in the north-eastern part of the bar (away from AT 2018cow). This region hosts a third of the galaxy's SFR. Conclusions. The absence of atomic gas concentration close to AT 2018cow, along with a normal SFR and regular HI velocity field, sets CGCG137-068 apart from GRB/SN hosts studied in HI. The environment of AT 2018cow therefore suggests that its progenitor may not have been a massive star. Our findings are consistent with an origin of the transient that does not require a connection between its progenitor and gas concentration or inflow: an exploding low-mass star, a tidal disruption event, a merger of white dwarfs, or a merger between a neutron star and a giant star. We interpret the recently reported atomic gas ring in CGCG 137-068 as a result of internal processes connected with gravitational resonances caused by the bar.© ESO 2019. ; M.J.M. acknowledges the support of the National Science Centre, Poland, through the POLONEZ grant 2015/19/P/ST9/04010 and SONATA BIS grant 2018/30/E/ST9/00208; this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665778. P.K. is supported by the BMBF project 05A17PC2 for D-MeerKAT J.H. was supported by a VILLUM FONDEN Investigator grant (project number 16599). D.A.K. acknowledges support from the Juan de la Cierva Incorporación fellowship IJCI-2015-26153. A.d.U.P. and C.C.T. acknowledge support from Ramón y Cajal fellowships (RyC-2012-09975 and RyC-2012-09984). D.A.K., A.d.U.P., and C.C.T. acknowledge support from the Spanish research project AYA2017-89384-P. L.K.H. acknowledges funding from the INAF PRIN-SKA program 1.05.01.88.04. The Cosmic Dawn Center is funded by the DNRF. R.L. acknowledges support from the grant EMR/2016/007127 from the Dept. of Science and Technology, India. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 679627; project name FORNAX; PI Paolo Serra). ; Peer Reviewed