TY - JOUR
T1 - Optical/Infrared Observations of the Extraordinary GRB 250702B
T2 - A Highly Obscured Afterglow in a Massive Galaxy Consistent with Multiple Possible Progenitors
AU - Carney, Jonathan
AU - Andreoni, Igor
AU - O’Connor, Brendan
AU - Freeburn, James
AU - Skobe, Hannah
AU - Westcott, Lewi
AU - Busmann, Malte
AU - Palmese, Antonella
AU - Hall, Xander J.
AU - Gill, Ramandeep
AU - Beniamini, Paz
AU - Coughlin, Eric R.
AU - Kilpatrick, Charles D.
AU - Anumarlapudi, Akash
AU - Law, Nicholas M.
AU - Corbett, Hank
AU - Ahumada, Tomas
AU - Chen, Ping
AU - Conselice, Christopher
AU - Damke, Guillermo
AU - Das, Kaustav K.
AU - Gal-Yam, Avishay
AU - Gruen, Daniel
AU - Heathcote, Steve
AU - Hu, Lei
AU - Karambelkar, Viraj
AU - Kasliwal, Mansi
AU - Labrie, Kathleen
AU - Pasham, Dheeraj
AU - Riffeser, Arno
AU - Schmidt, Michael
AU - Sharma, Kritti
AU - Wilke, Silona
AU - Zang, Weicheng
N1 - Publisher Copyright:
© 2025. The Author(s). Published by the American Astronomical Society.
PY - 2025/12/1
Y1 - 2025/12/1
N2 - GRB 250702B was the longest gamma-ray burst ever detected, with a duration that challenges standard collapsar models and suggests an exotic progenitor. We collected a rich set of optical and infrared follow-up observations of its rapidly fading afterglow using a suite of telescopes including the W. M. Keck Observatory, the Gemini telescopes, the Magellan Baade Telescope, the Victor M. Blanco 4 m telescope, and the Fraunhofer Telescope at Wendelstein Observatory. Our analysis reveals that the afterglow emission is well described by forward shock emission from a highly obscured relativistic jet. Deep photometric observations of the host galaxy reveal a massive (1010.66 M⊙), dusty, and extremely asymmetric system that is consistent with two galaxies undergoing a major merger. The galactocentric offset, host galaxy properties, and jet characteristics disfavor a jetted tidal disruption event (TDE) around a supermassive black hole but do not definitively distinguish between competing progenitor scenarios. We find that the afterglow and host are consistent with a range of progenitors, including an atypical collapsar, a merger between a helium star and a stellar-mass black hole, the disruption of a star by a stellar-mass compact object (micro-TDE), and the tidal disruption of a star by an off-nuclear intermediate-mass black hole.
AB - GRB 250702B was the longest gamma-ray burst ever detected, with a duration that challenges standard collapsar models and suggests an exotic progenitor. We collected a rich set of optical and infrared follow-up observations of its rapidly fading afterglow using a suite of telescopes including the W. M. Keck Observatory, the Gemini telescopes, the Magellan Baade Telescope, the Victor M. Blanco 4 m telescope, and the Fraunhofer Telescope at Wendelstein Observatory. Our analysis reveals that the afterglow emission is well described by forward shock emission from a highly obscured relativistic jet. Deep photometric observations of the host galaxy reveal a massive (1010.66 M⊙), dusty, and extremely asymmetric system that is consistent with two galaxies undergoing a major merger. The galactocentric offset, host galaxy properties, and jet characteristics disfavor a jetted tidal disruption event (TDE) around a supermassive black hole but do not definitively distinguish between competing progenitor scenarios. We find that the afterglow and host are consistent with a range of progenitors, including an atypical collapsar, a merger between a helium star and a stellar-mass black hole, the disruption of a star by a stellar-mass compact object (micro-TDE), and the tidal disruption of a star by an off-nuclear intermediate-mass black hole.
UR - https://www.scopus.com/pages/publications/105034014077
U2 - 10.3847/2041-8213/ae1d67
DO - 10.3847/2041-8213/ae1d67
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:105034014077
SN - 2041-8205
VL - 994
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L46
ER -