Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days

GRB 221009A is one of the brightest transients ever observed, with the highest peak gamma-ray flux for a gamma-ray burst (GRB). A Type Ic-BL supernova (SN), SN 2022xiw, was definitively detected in late-time JWST spectroscopy ( t = 195 days, observer frame). However, photometric studies have found S...

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Main Authors: Huei Sears, Ryan Chornock, Peter K. Blanchard, Raffaella Margutti, V. Ashley Villar, Justin Pierel, Patrick J. Vallely, Kate D. Alexander, Edo Berger, Tarraneh Eftekhari, Wynn V. Jacobson-Galán, Tanmoy Laskar, Natalie LeBaron, Brian D. Metzger, Dan Milisavljevic
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adc306
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_version_ 1850144540078374912
author Huei Sears
Ryan Chornock
Peter K. Blanchard
Raffaella Margutti
V. Ashley Villar
Justin Pierel
Patrick J. Vallely
Kate D. Alexander
Edo Berger
Tarraneh Eftekhari
Wynn V. Jacobson-Galán
Tanmoy Laskar
Natalie LeBaron
Brian D. Metzger
Dan Milisavljevic
author_facet Huei Sears
Ryan Chornock
Peter K. Blanchard
Raffaella Margutti
V. Ashley Villar
Justin Pierel
Patrick J. Vallely
Kate D. Alexander
Edo Berger
Tarraneh Eftekhari
Wynn V. Jacobson-Galán
Tanmoy Laskar
Natalie LeBaron
Brian D. Metzger
Dan Milisavljevic
author_sort Huei Sears
collection DOAJ
description GRB 221009A is one of the brightest transients ever observed, with the highest peak gamma-ray flux for a gamma-ray burst (GRB). A Type Ic-BL supernova (SN), SN 2022xiw, was definitively detected in late-time JWST spectroscopy ( t = 195 days, observer frame). However, photometric studies have found SN 2022xiw to be less luminous (10%−70%) than the canonical GRB-SN, SN 1998bw. We present late-time Hubble Space Telescope (HST)/WFC3 and JWST/NIRCam imaging of the afterglow and host galaxy of GRB 221009A at t ∼185, 277, and 345 days post-trigger. Our joint archival ground, HST, and JWST light-curve fits show strong support for a break in the light-curve decay slope at t = 50 ± 10 days (observer frame) and a SN at <1.5× the optical/near-IR flux of SN 1998bw. This break is consistent with an interpretation as a jet break when requiring slow-cooling electrons in a wind medium with an electron energy spectral index p > 2 and ν _m < ν _c . Our light curves and joint HST/JWST spectral energy distribution (SED) also show evidence for the late-time emergence of a bluer component in addition to the fading afterglow and SN. We find consistency with the interpretations that this source is either a young, massive, low-metallicity star cluster or a scattered-light echo of the afterglow with a SED shape of f _ν ∝ ν ^2.0±1.0 .
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spelling doaj-art-cd73aeb123734217a09676d29b6ea4912025-08-20T02:28:19ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01984219610.3847/1538-4357/adc306Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 daysHuei Sears0https://orcid.org/0000-0001-8023-4912Ryan Chornock1https://orcid.org/0000-0002-7706-5668Peter K. Blanchard2https://orcid.org/0000-0003-0526-2248Raffaella Margutti3https://orcid.org/0000-0003-4768-7586V. Ashley Villar4https://orcid.org/0000-0002-5814-4061Justin Pierel5https://orcid.org/0000-0002-2361-7201Patrick J. Vallely6https://orcid.org/0000-0001-5661-7155Kate D. Alexander7https://orcid.org/0000-0002-8297-2473Edo Berger8https://orcid.org/0000-0002-9392-9681Tarraneh Eftekhari9https://orcid.org/0000-0003-0307-9984Wynn V. Jacobson-Galán10https://orcid.org/0000-0003-1103-3409Tanmoy Laskar11https://orcid.org/0000-0003-1792-2338Natalie LeBaron12https://orcid.org/0000-0002-2249-0595Brian D. Metzger13https://orcid.org/0000-0002-4670-7509Dan Milisavljevic14https://orcid.org/0000-0002-0763-3885Department of Physics and Astronomy, Rutgers, the State University of New Jersey , 136 Frelinghuysen Road, Piscataway, NJ 08854-8019, USADepartment of Astronomy, University of California, Berkeley , CA 94720-3411, USACenter for Astrophysics | Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138-1516, USA; The NSF AI Institute for Artificial Intelligence and Fundamental Interactions , USADepartment of Astronomy, University of California, Berkeley , CA 94720-3411, USA; Department of Physics, University of California , 366 Physics North MC 7300, Berkeley, CA 94720, USACenter for Astrophysics | Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138-1516, USA; The NSF AI Institute for Artificial Intelligence and Fundamental Interactions , USASpace Telescope Science Institute , Baltimore, MD 21218, USACore Pricing Systems , CarMax, Inc., Richmond, VA 23238, USASteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721-0065, USACenter for Astrophysics | Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138-1516, USA; The NSF AI Institute for Artificial Intelligence and Fundamental Interactions , USACenter for Interdisciplinary Exploration and Research in Astronomy (CIERA), Northwestern University , 1800 Sherman Avenue, Evanston, IL 60201, USADepartment of Astronomy and Astrophysics, California Institute of Technology , Pasadena, CA 91125, USADepartment of Physics & Astronomy, University of Utah , Salt Lake City, UT 84112, USA; Department of Astrophysics/IMAPP, Radboud University , P.O. Box 9010, 6500 GL, Nijmegen, The NetherlandsDepartment of Astronomy, University of California, Berkeley , CA 94720-3411, USADepartment of Physics and Columbia Astrophysics Laboratory, Columbia University , New York, NY 10027, USA; Center for Computational Astrophysics , Flatiron Institute, 162 5th Ave, New York, NY 10010, USADepartment of Physics and Astronomy, Purdue University , 525 Northwestern Ave, West Lafayette, IN 47907, USAGRB 221009A is one of the brightest transients ever observed, with the highest peak gamma-ray flux for a gamma-ray burst (GRB). A Type Ic-BL supernova (SN), SN 2022xiw, was definitively detected in late-time JWST spectroscopy ( t = 195 days, observer frame). However, photometric studies have found SN 2022xiw to be less luminous (10%−70%) than the canonical GRB-SN, SN 1998bw. We present late-time Hubble Space Telescope (HST)/WFC3 and JWST/NIRCam imaging of the afterglow and host galaxy of GRB 221009A at t ∼185, 277, and 345 days post-trigger. Our joint archival ground, HST, and JWST light-curve fits show strong support for a break in the light-curve decay slope at t = 50 ± 10 days (observer frame) and a SN at <1.5× the optical/near-IR flux of SN 1998bw. This break is consistent with an interpretation as a jet break when requiring slow-cooling electrons in a wind medium with an electron energy spectral index p > 2 and ν _m < ν _c . Our light curves and joint HST/JWST spectral energy distribution (SED) also show evidence for the late-time emergence of a bluer component in addition to the fading afterglow and SN. We find consistency with the interpretations that this source is either a young, massive, low-metallicity star cluster or a scattered-light echo of the afterglow with a SED shape of f _ν ∝ ν ^2.0±1.0 .https://doi.org/10.3847/1538-4357/adc306Gamma-ray burstsCore-collapse supernovaeSupernovaeHigh energy astrophysicsHST photometryHubble Space Telescope
spellingShingle Huei Sears
Ryan Chornock
Peter K. Blanchard
Raffaella Margutti
V. Ashley Villar
Justin Pierel
Patrick J. Vallely
Kate D. Alexander
Edo Berger
Tarraneh Eftekhari
Wynn V. Jacobson-Galán
Tanmoy Laskar
Natalie LeBaron
Brian D. Metzger
Dan Milisavljevic
Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days
The Astrophysical Journal
Gamma-ray bursts
Core-collapse supernovae
Supernovae
High energy astrophysics
HST photometry
Hubble Space Telescope
title Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days
title_full Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days
title_fullStr Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days
title_full_unstemmed Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days
title_short Late-time HST and JWST Observations of GRB 221009A: Evidence for a Break in the Light Curve at 50 days
title_sort late time hst and jwst observations of grb 221009a evidence for a break in the light curve at 50 days
topic Gamma-ray bursts
Core-collapse supernovae
Supernovae
High energy astrophysics
HST photometry
Hubble Space Telescope
url https://doi.org/10.3847/1538-4357/adc306
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