Title: Spectral Studies of Gamma-Ray Bursts Detected by SPI aboard INTEGRAL
Proposal ID: 0120255
Subject category: Others
Principal investigator: Hanlon
Institute: University College Dublin
Abstract
One of the major difficulties with gamma-ray bursts (GRBs) being at cosmological distances (redshifts
between 0.83 and 4.5 so far) is the requirement that a phenomenal energy (of order 10^50 - 10^53 ergs
depending on beaming) be radiated primarily as non-thermal gamma-rays in a matter of seconds. Fireball
models of emission in which the deposition of the burst energy into a small volume produces an opaque
radiation plasma which expands relativistically can account for the general appearance of non-thermal
gamma-rays and for the progressively lower energy afterglows.
Some of the key scientific questions which
remain are:
What are the progenitors?
What is the emission mechanism which so efficiently generates the
observed GRB spectra?
Are there absorption and or emission lines in the spectra?
The motivation for this
proposal is to exploit the superb spectroscopic and broadband capabilities of the SPI instrument aboard
INTEGRAL and address these key questions by:
1. Tracking the GRB for about 1 day post-burst in order to
bridge the gap between burst and afterglow and possibly detect delayed MeV emission.
2. Testing theoretical
models of the emission process and spectral evolution. In particular the connection between temporal and
spectral properties will be studied.
3. Searching for evidence of gamma-ray absorption and emission lines
in GRB spectra and hence
distinguish between different progenitor scenarios.