Liverpool telescope Ringo 02: Glimpsing the infrastructure of a Gamma-Ray Burst jet

Measurements of polarized light in the afterglow of GRB 120308A by the Liverpool Telescope and its RINGO2 instrument indicate the presence of a large-scale stable magnetic field linked with a young black hole, as shown in this illustration. 

Credit: NASA's Goddard Space Flight Center/S. Wiessinger

A new study using observations from a novel instrument provides the best look to date at magnetic fields at the heart of gamma-ray bursts, the most energetic explosions in the universe.

An international team of astronomers from Britain, Slovenia and Italy has glimpsed the infrastructure of a burst's high-speed jet.

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.

The world's largest fully autonomous robotic optical telescope, the 2-meter Liverpool Telescope located at Roque de los Muchachos Observatory on La Palma in the Canary Islands, automatically responded to Swift's notification.

"Just four minutes after it received Swift's trigger, the telescope found the burst's visible afterglow and began making thousands of measurements," said 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.

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.

More information: Nature paper: "Highly polarized light from stable ordered magnetic fields in GRB 120308A," C. Mundell et al., www.nature.com/nature/journal/v504/n7478/full/nature12814.html