出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Using GX 3+1 as an example of a bright Atoll, GX 5-1 as an example of a Z source, and GX 13+1 as a peculiar hybrid, we take a look at the spectral and long-term time evolution differences in these three neutron star Low-Mass X-ray Binaries representing different subtypes. We utilize a recently developed spectral model based on mixed thermal and bulk motion Comptonization of soft seed photons from the accretion disc and the neutron star surface. The hard X-ray tails exhibited by GX 5-1 and GX 13+1 are attributed to efficient bulk motion Comptonization, which is not present in GX 3+1 due to too low or too high a local accretion rate. Accreting well below the Eddington limit also enables GX 3+1 to exhibit amplitude modulation presumably due to changes in the accretion output from the companion star, visible in the RXTE/ASMlight curve on a time scale of ∼6 years.
