@article{48fbaf6bffa44745b6b5d4379eaceec5,
title = "The First JWST Spectrum of a GRB Afterglow: No Bright Supernova in Observations of the Brightest GRB of all Time, GRB 221009A",
abstract = "We present James Webb Space Telescope (JWST) and Hubble Space Telescope (HST) observations of the afterglow of GRB 221009A, the brightest gamma-ray burst (GRB) ever observed. This includes the first mid-IR spectra of any GRB, obtained with JWST/Near Infrared Spectrograph (0.6-5.5 micron) and Mid-Infrared Instrument (5-12 micron), 12 days after the burst. Assuming that the intrinsic spectral slope is a single power law, with F ν ∝ ν −β , we obtain β ≈ 0.35, modified by substantial dust extinction with A V = 4.9. This suggests extinction above the notional Galactic value, possibly due to patchy extinction within the Milky Way or dust in the GRB host galaxy. It further implies that the X-ray and optical/IR regimes are not on the same segment of the synchrotron spectrum of the afterglow. If the cooling break lies between the X-ray and optical/IR, then the temporal decay rates would only match a post-jet-break model, with electron index p < 2, and with the jet expanding into a uniform ISM medium. The shape of the JWST spectrum is near-identical in the optical/near-IR to X-SHOOTER spectroscopy obtained at 0.5 days and to later time observations with HST. The lack of spectral evolution suggests that any accompanying supernova (SN) is either substantially fainter or bluer than SN 1998bw, the proto-type GRB-SN. Our HST observations also reveal a disk-like host galaxy, viewed close to edge-on, that further complicates the isolation of any SN component. The host galaxy appears rather typical among long-GRB hosts and suggests that the extreme properties of GRB 221009A are not directly tied to its galaxy-scale environment.",
author = "Levan, {A. J.} and Lamb, {G. P.} and B. Schneider and J. Hjorth and T. Zafar and {de Ugarte Postigo}, A. and B. Sargent and Mullally, {S. E.} and L. Izzo and P. D{\textquoteright}Avanzo and E. Burns and Fern{\'a}ndez, {J. F.Ag{\"u}{\'i}} and T. Barclay and Bernardini, {M. G.} and K. Bhirombhakdi and M. Bremer and R. Brivio and S. Campana and Chrimes, {A. A.} and V. D{\textquoteright}Elia and Valle, {M. Della} and {De Pasquale}, M. and M. Ferro and W. Fong and Fruchter, {A. S.} and Fynbo, {J. P.U.} and N. Gaspari and Gompertz, {B. P.} and Hartmann, {D. H.} and Hedges, {C. L.} and Heintz, {K. E.} and K. Hotokezaka and P. Jakobsson and Kann, {D. A.} and Kennea, {J. A.} and T. Laskar and {Le Floc{\textquoteright}h}, E. and Malesani, {D. B.} and A. Melandri and Metzger, {B. D.} and Oates, {S. R.} and E. Pian and S. Piranomonte and G. Pugliese and Racusin, {J. L.} and Rastinejad, {J. C.} and Ravasio, {M. E.} and A. Rossi and A. Saccardi and R. Salvaterra and B. Sbarufatti and Starling, {R. L.C.} and Tanvir, {N. R.} and Th{\"o}ne, {C. C.} and {van der Horst}, {A. J.} and Vergani, {S. D.} and D. Watson and K. Wiersema and Wijers, {R. A.M.J.} and Dong Xu",
note = "Funding Information: This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program(s) 17264. This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program No. 2782. Partly based on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\'i}sica de Canarias, on the island of La Palma. Partly based on observations carried out under project Nos. S22BC with the IRAM NOEMA Interferometer. I.R.A.M. is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). Partly based on observations collected at the European Southern Observatory under ESO program 110.24CF (PI Tanvir). Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundaci{\'o}n Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Funding Information: A.J.L., D.B.M., and N.R.T. are supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 725246). G.P.L. is supported by a Royal Society Dorothy Hodgkin Fellowship (grant Nos. DHF-R1-221175 and DHF-ERE-221005). J.H. and L.I. were supported by a VILLUM FONDEN Investigator grant to JH (project No. 16599). B.D.M. acknowledges support from the National Science Foundation (grant No. AST-2002577). J.P.U.F. acknowledges support from the Carlsberg Foundation. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant No. 140. D.A.K. acknowledges the support by the State of Hessen within the Research Cluster ELEMENTS (Project ID 500/10.006). R.B., M.G.B., S.C., P.D.A., M.F., A.M., and S.P. acknowledge funding from the Italian Space Agency, contract ASI/INAF No. I/004/11/4. P.D.A. acknowledges support from PRIN-MIUR 2017 (grant 20179ZF5KS). J.F.A.F. acknowledges support from the Spanish Ministerio de Ciencia, Innovaci{\'o}n y Universidades through the grant PRE2018-086507. Publisher Copyright: {\textcopyright} 2023. The Author(s). Published by the American Astronomical Society.",
year = "2023",
month = mar,
day = "1",
doi = "10.3847/2041-8213/acc2c1",
language = "English (US)",
volume = "946",
journal = "Astrophysical Journal Letters",
issn = "2041-8205",
publisher = "IOP Publishing Ltd.",
number = "1",
}