A brilliant-short gamma-ray burst defies astronomers’ expectations

A brilliant-short gamma-ray burst defies astronomers’ expectations

A surprisingly brief gamma-ray burst has astronomers rethinking what triggers these celestial cataclysms.

The Fermi Gamma-ray House Telescope detected a single-second-long blast of gamma rays, dubbed GRB 200826A, in August 2020. Such fleeting gamma-ray bursts, or GRBs, are normally thought to originate from neutron star smashups (SN: 10/16/17). However a more in-depth take a look at the burst revealed that it got here from the implosion of an enormous star’s core.

On this situation, the core of a star collapses right into a compact object, comparable to a black gap, that powers high-speed particle jets. These jets punch by the remainder of the star and radiate highly effective gamma rays earlier than the outer layers of the star explode in a supernova (SN: 5/8/19). That course of is often thought to provide longer GRBs, lasting greater than two seconds.

Discovering such a quick gamma-ray burst from a stellar explosion means that some bursts beforehand categorised as stellar mergers may very well be from the deaths of large stars, researchers report on-line July 26 in two research in Nature Astronomy.

The primary clues about GRB 200826A’s origin got here from the burst itself. The wavelengths of sunshine and quantity of power launched within the burst had been extra just like collapse-related GRBs than collision-produced bursts, Bing Zhang, an astrophysicist on the College of Nevada, Las Vegas, and colleagues report. Plus, the burst hailed from the center of a star-forming galaxy, the place astronomers look forward to finding collapsing large stars, however not neutron star mergers — that are typically discovered on the fringes of tranquil galaxies.

One other group, led by astronomer Tomás Ahumada-Mena of the College of Maryland in School Park, looked for the supernova that’s anticipated to comply with a GRB produced by a collapsing star. Utilizing the Gemini North Telescope in Hawaii to watch GRB 200826A’s host galaxy, the group was ready to pick the telltale infrared gentle of the supernova. The burst could have been so temporary as a result of its jets had simply barely punched by the floor of the star earlier than they petered out and the star blew up, Ahumada-Mena says.

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