A burst of gamma rays of unprecedented intensity, variability and duration has been discovered by astronomers using gamma and x ray detectors on NASA satellites. Gamma bursts last only a few hours, but this gamma burst has been going on for over a week. Because the burst has highly variable brightness, astronomers have proposed that it is an intense gamma ray beam focused directly at our solar system, from the black hole heart of a distant galaxy, across a vast expanse of space and three and a half billion years of time.
Images from Swift's Ultraviolet/Optical (white, purple) and X-ray telescopes (yellow and red) were combined in this view of GRB 110328A. The blast was detected only in X-rays, which were collected over a 3.4-hour period on March 28. Credit: NASA/Swift/Stefan Immler
This video shows a supercomputer model animation of a normal gamma ray burst.
Measurements of this unprecedented gamma ray burst show it lasting for days when a normal burst from the merger of 2 neutron stars to become a black hole would be over in a few hours, at most.
Astronomers say they have never seen anything this bright, long-lasting and variable before. Usually, gamma-ray bursts mark the destruction of a massive star, but flaring emission from these events never lasts more than a few hours.
Although research is ongoing, astronomers say that the unusual blast likely arose when a star wandered too close to its galaxy's central black hole. Intense tidal forces tore the star apart, and the infalling gas continues to stream toward the hole. According to this model, the spinning black hole formed an outflowing jet along its rotational axis. A powerful blast of X- and gamma rays is seen if this jet is pointed in our direction.
"We have been eagerly awaiting the Hubble observation," said Neil Gehrels, the lead scientist for Swift at NASA's Goddard Space Flight Center in Greenbelt, Md. "The fact that the explosion occurred in the center of a galaxy tells us it is most likely associated with a massive black hole. This solves a key question about the mysterious event."
This video shows an animation of an energy beam created by the infalling of matter from a star that is being ripped apart by a black hole.
"The best explanation at the moment is that we happen to be looking down the barrel of this jet," said Andrew Levan at the University of Warwick in the United Kingdom, who led the Chandra observations. "When we look straight down these jets, a brightness boost lets us view details we might otherwise miss."
This brightness increase, which is called relativistic beaming, occurs when matter moving close to the speed of light is viewed nearly head on.