Open AccessPrecursor activity in bright, long BATSE gamma‐ray bursts
Author(s) -
Lazzati Davide
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.08687.x
Subject(s) - physics , gamma ray burst , astrophysics , spectral line , light curve , thermal , power law , gamma ray , astronomy , statistics , mathematics , meteorology
We study a sample of bright, long Burst and Transient Source Experiment (BATSE) gamma‐ray burst (GRB) light curves in the 200 s before the detection of the GRB prompt emission. We find that in a sizable fraction of cases (∼20 per cent) there is evidence of emission above the background coming from the same direction as the GRB. This emission is characterized by a softer spectrum with respect to the main spectrum and contains a small fraction (0.1–1 per cent) of the total event counts. The precursors have typical delays of several tens of seconds extending (in few cases) up to 200 s (the limit of the investigated period). Their spectra are typically non‐thermal power‐law spectra, aside from a few cases. Such long delays and the non‐thermal origin of their spectra are hard to reconcile with any model for the progenitor.