spacetoday.net: Dark GRBs linked to dust clouds

Dark GRBs linked to dust clouds

Posted: Tue, Jun 9, 2009, 8:22 AM ET (1222 GMT)
Dark GRB illustration (NASA/Swift/Aurore Simonnet)

A class of gamma-ray bursts (GRBs) without a visible afterglow have been linked to galaxies with previously undetected dust clouds, astronomers announced Monday. "Dark" GRBs are so named because they have no detectable afterglow as visible or infrared wavelengths. Astronomers originally thought these GRBs were so distant that the light had been redshifted beyond detection. However, astronomers studied 14 such bursts and found that almost every one of them was associated with a galaxy that was visible in optical telescopes. Astronomers now believe the optical afterglow of these GRBs was absorbed by clouds of dust, perhaps associated with regions of star formation, not previously detected around these galaxies.