1996A&AS..120C.133T -
Astron. Astrophys., Suppl. Ser., 120C, 133-136 (1996/December-3)
Hard X-ray emission from X-ray bursters.
TAVANI M. and LIANG E.
Abstract (from CDS):
Hard X-ray emission from compact objects has been considered a spectral signature of black hole candidates. However, SIGMA and BATSE recently detected transient emission in the energy range 30-200keV from several X-ray bursters (XRBs) believed to contain weakly magnetized neutron stars. At least seven XRBs (including Aquila X-1 and 4U 1608-52) are currently known to produce erratic hard X-ray outbursts with typical durations of several weeks. These results lead us to reconsider theoretical models of high-energy emission from compact objects, and in particular thermal Comptonization models vs. non-thermal models of particle energization and X-ray emission from weakly magnetized neutron stars. We summarize here recent results for magnetic field reconnection models of non-thermal particle acceleration and high-energy emission of accretion disks. For intermediate soft X-ray luminosities below the Eddington limit, non-thermal hard X-ray emission is predicted to have a (broken) power-law spectrum with intensity anticorrelated with the soft X-ray luminosity. Recent GINGA/BATSE data for the XRB 4U 1608-52 are in agreement with the mechanism of emission proposed here: transient hard X-ray emission consistent with a broken power-law spectrum was detected for a sub-Eddington soft X-ray luminosity.
Abstract Copyright:
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Journal keyword(s):
X-rays: stars - X-rays: bursts - acceleration of particles - stars: individual: 4U 1608-52
CDS comments:
Special Issue "3rd Compton Symposium"
Simbad objects:
8
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