The Hard X-ray Variability of the LMC X-1 system
Abstract
Only two parameters are needed to completely describe the physics of a black hole: its mass and its spin. This is true for both stellar mass black holes as well as for the supermassive black holes that reside in the centers of most galaxies. While these two parameters are fundamental to our understanding of black holes, accurately measuring the spin of a black hole is a challenge in modern astrophysics and many spins of black hole systems are only measurable when the system goes into outburst and the luminosity increases to nearly the Eddington limit from quiescence (∼1e-6 Eddington). Persistently accreting systems, in contrast, should instead allow to probe accretion physics in a more steady-state accretion mode. We report on NuSTAR and XMM observations of the persistent wind-fed black hole binary LMC X-1, which is a moderately accreting (10% Eddington) system. Over two NuSTAR epochs and one joint NuSTAR-XMM observations we find significant variation in the hardness and intensity of the source as well as an X-ray flare observed by both XMM and NusTAR. The variability of the source impacts the measurement of the spin of the black hole and the interpretation of the X-ray spectrum. We will discuss our findings, and the implications of these results.
- Publication:
-
AAS/High Energy Astrophysics Division #16
- Pub Date:
- August 2017
- Bibcode:
- 2017HEAD...1640003G