The Long and Short of Gamma-Ray Bursts: A Tale of Brightness

Scientists have been studying the lengths of gamma-ray bursts (GRBs) detected by the BATSE experiment on NASA's Compton Gamma Ray Observatory. They measured the time it takes for 5% to 95% of the burst's light to arrive, known as T90 duration, and the time for 25% to 75% (called T50), from both bright and dim bursts. Out of 775 bursts observed, 159 with durations longer than 1. 5 seconds were selected for this study.

Ever wondered why some GRBs seem to flash quicker than others? Research shows that dim GRBs can last roughly twice as long as bright ones. Tests confirm that the chance of them coming from the same source is extremely low, less than one in ten thousand. This "time dilation" effect isn't fussy about which energy range you look at. Picture this: if these dim GRBs are happening far away in the universe, they might be coming from places that are about twice as distant as the bright ones, kind of like looking back in time. These findings agree with past studies on a smaller set of GRBs, so they seem to be on the right track.

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