Temporal properties of short gamma-ray bursts

We analyse a sample of bright short bursts from the BATSE 4B-catalog and find that many short bursts are highly variable  ( δt _min/ T ≪1  , where δt _min is the shortest pulse duration and T is the burst duration). This indicates that it is unlikely that short bursts are produced by external shocks. We also analyse the available (first  1–2 s)  high-resolution Time Tagged Events (TTE) data of some of the long bursts. We find that variability on a 10-ms time-scale is common in long bursts. This result shows that some long bursts are even more variable than it was thought before  ( δt _min/ T ≈10^-4–10^-3)  .