This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Astronomers have observed the longest-lasting central engine activity ever recorded from a gamma-ray burst. The burst occurred at a redshift of 0.8577, and the activity lasted about 27 days in the burst's own rest frame—around 20 days longer than the previous record.
The paper, posted to the arXiv preprint server on Sept. 18, explores different mechanisms that could be powering this puzzling burst. Gamma-ray bursts (GRBs) are among the most energetic explosions in the universe, typically linked to the collapse of massive stars into black holes (producing long-duration GRBs, often with an accompanying supernova) or the merger of neutron stars (producing short-duration GRBs). Ultra-long GRBs are a rare subclass of gamma-ray bursts in which the object driving or powering the explosion stays active longer than in typical bursts.
Only a handful of confirmed examples exist, and their cause remains debated. Understanding what powers these rare ultra-long bursts helps explain how massive stars die and what kind of compact object is left behind. GRB 220706A was first detected on July 6, 2022.
The burst kept flaring in X-rays for nearly a month. In this study, the team led by Benjamin P. Gompertz of the University of Birmingham conducted a detailed, multiwavelength study of this mysterious event.
The team used X-ray data from the Swift X-ray Telescope, the Neutron Star Interior Composition Explorer (NICER) and the Chandra X-ray Observatory; optical/infrared imaging from four different ground-based telescopes; and radio/millimeter observations from NOEMA and the Karl G. Jansky Very Large Array (VLA). These follow-up observations across multiple wavelengths spanned the period from around 100 seconds after the initial burst to Oct. 5, 2023.
The team found that GRB 220706A ranks eighth-longest among 549 GRBs analyzed. Its initial burst lasted about 15.6 hours, exceeding even the previously known "archetypal" ultra-long GRBs. X-ray observations of GRB 220706A revealed repeated flaring activity that continued for about 51 days after the burst was first detected.
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