GRB 220706A: a gamma-ray burst with a month-long engine and a luminous supernova
Abstract
While the progenitors of many long gamma-ray bursts (GRBs) are well established as the core collapse of very massive, envelope-stripped, rapidly-rotating stars, it has been suggested that bursts at the extremely long end of the duration distribution may be a separate population of `ultra-long' GRBs. With durations of thousands of seconds or more, these bursts are difficult to reconcile with the engine timescales expected from the compact Wolf-Rayet stars that are typically assumed to produce more `standard' long GRBs. Here, we present observations of GRB~220706A, where X-ray follow-up reveals flaring episodes that last until ≈ 51 days after trigger. At the measured redshift of z = 0.8577, this corresponds to 27 days in the GRB rest frame, and represents the latest central engine activity ever observed in a GRB by a margin of ≈ 21 rest-frame days. We also identify a likely supernova (SN) which, when accounting for the inferred optical extinction of 0.9 ≤ AV ≤ 3.6 mag (constrained by indirect arguments), has a peak absolute magnitude of Mr ≤ −20.25, resembling the energetic SN\,2011kl found accompanying ultra-long GRB\,111209A, and consistent with super-luminous SNe. We discuss the implications GRB~220706A has for ultra-long GRB progenitor models and possible powering mechanisms for the extremely late central engine activity.
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BibTeX
@misc{gompertz2026220706a,
title = {{GRB 220706A: a gamma-ray burst with a month-long engine and a luminous supernova}},
author = {Benjamin P. Gompertz and Nusrin Habeeb and Dheeraj R. Pasham and Antonio de Ugarte Postigo and Daniele B. Malesani and Phil A. Evans and Kim L. Page and Ben Rayson and J. Feliciano Agui Fernandez and Michael Bremer and Andrew J. Levan and Genevieve Schroeder and Nial R. Tanvir and Christina C. Thone and Eric Burns and Valerio D'Elia and Massimiliano De Pasquale and Dimple and Dieter Hartmann and Pall Jakobsson and Sylvio Klose and Antonio Martin-Carrillo and Matt Nicholl and Ana M. Nicuesa Guelbenzu and David O'Neill and Giovanna Pugliese and Arne Rau and Andrea Rossi and Jesper Sollerman and Rhaana Starling and Darach Watson and Isabelle Worssam and Makenzie E. Wortley},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.22426},
eprint = {2609.22426},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.22426},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - GRB 220706A: a gamma-ray burst with a month-long engine and a luminous supernova
AU - Benjamin P. Gompertz
AU - Nusrin Habeeb
AU - Dheeraj R. Pasham
AU - Antonio de Ugarte Postigo
AU - Daniele B. Malesani
AU - Phil A. Evans
AU - Kim L. Page
AU - Ben Rayson
AU - J. Feliciano Agui Fernandez
AU - Michael Bremer
AU - Andrew J. Levan
AU - Genevieve Schroeder
AU - Nial R. Tanvir
AU - Christina C. Thone
AU - Eric Burns
AU - Valerio D'Elia
AU - Massimiliano De Pasquale
AU - Dimple
AU - Dieter Hartmann
AU - Pall Jakobsson
AU - Sylvio Klose
AU - Antonio Martin-Carrillo
AU - Matt Nicholl
AU - Ana M. Nicuesa Guelbenzu
AU - David O'Neill
AU - Giovanna Pugliese
AU - Arne Rau
AU - Andrea Rossi
AU - Jesper Sollerman
AU - Rhaana Starling
AU - Darach Watson
AU - Isabelle Worssam
AU - Makenzie E. Wortley
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.22426
UR - https://arxiv.org/abs/2609.22426
AB - While the progenitors of many long gamma-ray bursts (GRBs) are well established as the core collapse of very massive, envelope-stripped, rapidly-rotating stars, it has been suggested that bursts at the extremely long end of the duration distribution may be a separate population of `ultra-long' GRBs. With durations of thousands of seconds or more, these bursts are difficult to reconcile with the engine timescales expected from the compact Wolf-Rayet stars that are typically assumed to produce more `standard' long GRBs. Here, we present observations of GRB~220706A, where X-ray follow-up reveals flaring episodes that last until ≈ 51 days after trigger. At the measured redshift of z = 0.8577, this corresponds to 27 days in the GRB rest frame, and represents the latest central engine activity ever observed in a GRB by a margin of ≈ 21 rest-frame days. We also identify a likely supernova (SN) which, when accounting for the inferred optical extinction of 0.9 ≤ A_V ≤ 3.6 mag (constrained by indirect arguments), has a peak absolute magnitude of M_r ≤ −20.25, resembling the energetic SN\,2011kl found accompanying ultra-long GRB\,111209A, and consistent with super-luminous SNe. We discuss the implications GRB~220706A has for ultra-long GRB progenitor models and possible powering mechanisms for the extremely late central engine activity.
ER -