NASA – This “tidal disruption” event may have been caught in real time, rather than detected later from analyzing archival observations. However, this X-ray source is about a hundred times brighter than previously observed tidal disruptions. One possible explanation for this very bright radiation is that debris from the disrupted star fell towards the black hole in a disk and the swirling, magnetized matter generated intense electromagnetic fields that created a powerful jet of particles. If this jet is pointed toward Earth it would boost the observed brightness of the source.
This observation was part of a so-called target of opportunity, or TOO, led by Andrew Levan from the University of Warwick in the UK. A TOO allows the telescope to react quickly to unpredictable cosmic events, within 24 hours in some situations. Chandra scientists and engineers can decide to alter the scheduled observations and instead point the telescope to another target if the circumstances warrant it. This process was put into place once the discovery of GRB 110328A with Swift was announced on March 28th, 2011. The Chandra team was able to reset the telescope’s schedule to observe GRB 110328A early in the morning of Monday, April 4th for a period of just over four hours.
GRBs longer than two seconds are the most common type and are widely thought to be triggered by the collapse of a massive star into a black hole. As matter falls toward the black hole, some of it forms jets in the opposite direction that move near the speed of light. These jets bore through the collapsing star along its rotational axis and produce a blast of gamma rays after they emerge. Understanding short GRBs, which fade quickly, proved more elusive. Astronomers had difficulty obtaining precise positions for follow-up studies.
That began to change in 2004, when NASA’s Swift satellite began rapidly locating bursts and alerting astronomers where to look.
“For more than two decades, the leading model of short GRBs was the merger of two neutron stars,” said co-author Bruno Giacomazzo at the University of Maryland and NASA’s Goddard Space Flight Center in Greenbelt, Md. “Only now can we show that the merger of neutron stars actually produces an ultrastrong magnetic field structured like the jets needed for a GRB.” more> http://twurl.nl/ytjrux
- Scientists ID mysterious flash in distant galaxy, Alicia Chang, AP/R&D Mag