ALMA: Enduring ‘Radio Rebound’ Powered by Jets from Gamma-Ray Burst

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ALMA: Enduring ‘Radio Rebound’ Powered by Jets from Gamma-Ray Burst

Post by bystander » Fri Jul 27, 2018 3:45 am

Enduring ‘Radio Rebound’ Powered by Jets from Gamma-Ray Burst
ALMA | NRAO | NAOJ | ESO | 2018 Jul 26

ALMA Creates Its First-ever Movie of Cosmic Explosion

Astronomers using ALMA studied a cataclysmic stellar explosion known as a gamma-ray burst, or GRB, and found its enduring “afterglow.” The rebound, or reverse shock, triggered by the GRB’s powerful jets slamming into surrounding debris, lasted thousands of times longer than expected. These observations provide fresh insights into the physics of GRBs, one of the universe’s most energetic explosions.

In the blink of an eye, a massive star more than 2 billion light-years away lost a million-year-long fight against gravity and collapsed, triggering a supernova and forming a black hole at its center.

This newborn black hole belched a fleeting yet astonishingly intense flash of gamma rays known as a gamma-ray burst (GRB) toward Earth, where it was detected by NASA’s Neil Gehrels Swift Observatory on 19 December 2016.

While the gamma rays from the burst disappeared from view a scant seven seconds later, longer wavelengths of light from the explosion — including X-ray, visible light, and radio — continued to shine for weeks. This allowed astronomers to study the aftermath of this fantastically energetic event, known as GRB 161219B, with many ground-based observatories, including the National Science Foundation’s Very Large Array.

The unique capabilities of the Atacama Large Millimeter/submillimeter Array (ALMA), however, enabled a team of astronomers to make an extended study of this explosion at millimeter wavelengths, gaining new insights into this particular GRB and the size and composition of its powerful jets. ...

First ALMA Light Curve Constraints Refreshed Reverse Shocks and Jets Magnetization in GRB 161219B - T. Laskar et al
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