Presentation details
» Global Characteristics of INTEGRAL GRBs
Presentation duration: 20 minutes
Presenter: Suzanne Foley
INTEGRAL’s main gamma-ray instruments detected and localised 56 gamma-ray bursts (GRBs) from its launch in October 2002 up to August 2008. The spectral, spatial, and temporal properties of these bursts will be presented and compared with the results from other missions. Spectral lags, i.e. the time delay in the arrival of low-energy gamma-rays with respect to high-energy gamma-rays, are measured for 31 of the GRBs. Two groups are identified in the spectral lag distribution of INTEGRAL GRBs, one with short lags <0.75 s (between 25-50 keV and 50-300 keV) and one with long lags >0.75 s. Most of the long-lag GRBs are inferred to have low redshifts because of their long spectral lags, their tendency to have low peak energies, and their faint optical and X-ray afterglows. They are mainly observed in the direction of the supergalactic plane with a quadrupole moment of Q=-0.225 ± 0.090 and hence reflect the local large-scale structure of the Universe. The rate of long-lag GRBs with inferred low luminosity is ~25% of type Ib/c supernovae. Some of these bursts could be produced by the collapse of a massive star without a supernova. Alternatively, they could result from a different progenitor, such as the merger of two white dwarfs.
Coauthors:- Sinead McGlynn
- Lorraine Hanlon
- Sheila McBreen
- Brian McBreen