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 may have finally solved the mystery behind a nearly two-decade-old cosmic explosion that seemed to break the rules of physics. The energy output of a powerful gamma-ray burst, GRB 061201, discovered in 2006, did not match well-established patterns seen in other similar explosions.
Now, in a new study published in the Astrophysical Journal on Aug. 3, astronomers have revealed why. Gamma-ray bursts (GRBs) are among the most violent and energetic events in the universe. For nearly two decades, one gamma-ray burst refused to give up its secrets.
When GRB 061201 flared briefly in the sky in 2006, astronomers detected its fading afterglow but found no obvious galaxy at its location. A short GRB such as GRB 061201 is generally thought to occur when two extremely dense, compact objects, such as two neutron stars or a neutron star and a black hole, spiral into each other and merge. To understand what triggered the burst, astronomers need to know how far away the host galaxy is, which lets them calculate the true energy released, how focused the burst's jet was and other key physical properties.
This GRB was long classified as a "hostless" burst. Two competing theories tried to explain its origin: Either the burst occurred in a nearby galaxy (G1) at a redshift z = 0.111, or the host galaxy was simply too faint and too far away for existing telescopes to detect. The problem with the nearby-galaxy theory is that it would require an implausibly narrow jet to match the burst's properties, pushing its total energy output well outside the normal pattern seen in other short bursts.
It also implies an unusually high rate of these compact-object mergers occurring nearby, which conflicts with independent measurements from gravitational-wave detectors. Both cases suggest the true host galaxy sits much farther away than the nearby-galaxy explanation assumed. In this new study, led by Yuhan Mao of the Purple Mountain Observatory, Chinese Academy of Sciences, the team used deep imaging from the James Webb Space Telescope and Hubble Space Telescope to search for a more distant host-galaxy candidate for the burst.
Examining the same patch of sky where the burst was detected, the team spotted a previously undetected, extremely faint galaxy (G2) very close to the burst's position. They also spotted an even fainter, closer object (G3). Using its brightness pattern across multiple wavelengths—a technique called spectral energy distribution fitting—they estimated G2's redshift at about z = 1.2, consistent with earlier indirect distance limits from the original afterglow data.
Extract — continue reading at the source.
