GRB halo
Credit: ESA, S. Vaughan (University of Leicester)

Fog Lights

Halos are a fairly familiar phenomena. The can be seen around headlights on foggy nights, and can even be seen, sometimes, around the moon. Astronomers have now seen haloes around an extremely powerful, distant "headlight", a gamma-ray burst which occurred for about 30 seconds on December 3, 2003. The GRB was detected by the INTEGRAL observatory and soon afterwards, an X-ray "afterglow" from the GRB was observed by XMM-Newton observatory. As the afterglow was observed through the disk of our Galaxy, sheets of dust in the Galaxy scattered the X-rays and produced the halo. Four images of the "GRB halo", obtained 25, 35, 45, and 55 thousand seconds after the GRB, are shown above. The X-ray afterglow from the GRB is at the center of each halo. The haloes seem to be expanding, but this is an optical illusion; it simply takes a bit longer for the X-rays to be scattered by the more distant dust.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:28:21 EDT