Quiescent emission in accreting neutron star transients: comparing Cen X-4 and the transitional millisecond pulsars
Abstract
Many accreting neutron star in low-mass X-ray binaries are transient X-ray sources, undergoing bright X-ray outbursts lasting days to weeks alternating with long quiescent intervals lasting months to years. The origin of their faint quiescent power-law X-ray emission has been a longstanding question, with theorists primarily debating between Comptonization and synchrotron shock models. However, recent NuSTAR observations of the nearby source Cen X-4 unexpectedly revealed a bremsstrahlung origin for the quiescent hard X-ray component. I will discuss the implications of this result, and will also compare Cen X-4 with the "transitional" millisecond pulsars, which exhibit markedly different behavior at comparable X-ray luminosities.
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- Bibcode:
- 2016cosp...41E.312C