Astronomers glimpse infrastructure of Gamma-ray burst jets
Astronomers have used observations from a novel instrument to look at magnetic fields at the heart of gamma-ray bursts, the most energetic explosions in the universe.
Washington: Astronomers have used observations from a novel instrument to look at magnetic fields at the heart of gamma-ray bursts, the most energetic explosions in the universe.
Gamma-ray bursts are the most luminous explosions in the cosmos. Most are thought to be triggered when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole.
The black hole then drives jets of particles that drill all the way through the collapsing star and erupt into space at nearly the speed of light.
On March 8, 2012, NASA`s Swift satellite detected a 100-second pulse of gamma rays from a source in the constellation Ursa Minor.
The spacecraft immediately forwarded the location of the gamma-ray burst, dubbed GRB 120308A, to observatories around the globe.
Lead researcher Carole Mundell, who heads the gamma-ray burst team at the Astrophysics Research Institute at Liverpool John Moores University in the U.K, said that just four minutes after it received Swift`s trigger, the telescope found the burst`s visible afterglow and began making thousands of measurements.
The telescope was fitted with an instrument named RINGO2, which Mundell`s team designed to detect any preferred direction, called polarization, in the vibration of light waves from burst afterglows.
The Liverpool Telescope`s rapid targeting enabled the team to catch the explosion just four minutes after the initial outburst. Over the following 10 minutes, RINGO2 collected 5,600 photographs of the burst afterglow while the properties of the magnetic field were still encoded in its captured light.
The observations show that the initial afterglow light was polarized by 28 percent, the highest value ever recorded for a burst, and slowly declined to 16 percent, while the angle of the polarized light remained the same.
The paper has been published in the journal Nature.