GRB 250702B: Discovery of a Gamma-Ray Burst from a Black Hole Falling into a Star
Authors
Eliza Neights
Eric Burns
Chris L. Fryer
Dmitry Svinkin
Suman Bala
Rachel Hamburg
Ramandeep Gill
Michela Negro
Megan Masterson
James DeLaunay
David J. Lawrence
Sophie E. D. Abrahams
Yuta Kawakubo
Paz Beniamini
Christian Aa. Diget
Dmitry Frederiks
John Goldsten
Adam Goldstein
Alexander D. Hall-Smith
Erin Kara
Alison M. Laird
Gavin P. Lamb
Oliver J. Roberts
Ryan Seeb
V. Ashley Villar
Aldana Holzmann Airasca
Joseph R. Barber
P. Narayana Bhat
Elisabetta Bissaldi
Michael S. Briggs
William H Cleveland
Sarah Dalessi
Davide Depalo
Misty M. Giles
Jonathan Granot
Boyan A. Hristov
C. Michelle Hui
Andreas von Kienlin
Carolyn Kierans
Daniel Kocevski
Stephen Lesage
Alexandra L. Lysenko
Bagrat Mailyan
Christian Malacaria
Tyler Parsotan
Anna Ridnaia
Samuele Ronchini
Lorenzo Scotton
Aaron C. Trigg
Anastasia Tsvetkova
Mikhail Ulanov
Péter Veres
Maia Williams
Colleen A. Wilson-Hodge
Joshua Wood
Abstract
Gamma-ray bursts are the most luminous electromagnetic events in the universe. Their prompt gamma-ray emission has typical durations between a fraction of a second and several minutes. A rare subset of these events have durations in excess of a thousand seconds, referred to as ultra-long gamma-ray bursts. Here, we report the discovery of the longest gamma-ray burst ever seen with a ~25,000 s gamma-ray duration, GRB 250702B, and characterize this event using data from four instruments in the InterPlanetary Network and the Monitor of All-sky X-ray Image. We find a hard spectrum, subsecond variability, and high total energy, which are only known to arise from ultrarelativistic jets powered by a rapidly-spinning stellar-mass central engine. These properties and the extreme duration are together incompatible with all confirmed gamma-ray burst progenitors and nearly all models in the literature. This burst is naturally explained with the helium merger model, where a field binary ends when a black hole falls into a stripped star and proceeds to consume and explode it from within. Under this paradigm, GRB 250702B adds to the growing evidence that helium stars expand and that some ultra-long GRBs have similar evolutionary pathways as collapsars, stellar-mass gravitational wave sources, and potentially rare types of supernovae.
