But the findings from the Goddard scientists may provide the tools needed to pinpoint their point of origin, distance traveled and age. Norris explained that, in a single burst, gamma rays of different energies reached Earth-orbiting detectors at slightly different times. The amount of lag time between the two corresponded to the to the burst's peak brightness and distance. Gamma-ray bursts were discovered in the late 1960s. Only recently have most astronomers agreed that many of them originate in the very distant, early universe.
Redshift is a common measurement of astronomical distances.
The more distant an object is from Earth, the faster it is receding due to the expansion of the universe, and the more its light is stretched, or redshifted. Objects at high redshift thus serve as probes to the early universe because their light has taken billions of years to reach Earth. A future with more gamma data Appropriate methods of measuring gamma-ray redshift have thus far been elusive. Of the thousands of gamma-ray bursts detected, fewer than 10 had an afterglow or host galaxy whose redshift could be determined with optical telescopes. Goddard scientists say their new method of comparative measurement of the time between high energy and low energy rays has the potential to gauge the distance of many bursts.