报告题目：How Should We Measure the Black Hole Mass in Soft X-ray Transients -- A Case Study of Nova Muscae 1991

报 告 人：Jianfeng Wu

报告时间：2016年7月14日16：00

报告地点：蒙民伟科技南楼S727

报告摘要：Mass is the fundamental parameter for an astrophysical black hole. However, for many soft X-ray transients, there are wide discrepancies on their black hole mass measurements. The biggest challenge is to determine the systemic inclination from the optical light curves, which (presumably from the companion star) are often significantly contaminated by the emission from accretion disk. In this talk, I will report a novel approach that we have developed to successfully correct for this "disk veiling" effect. We utilize 72 high resolution Magellan Echellette (MagE) spectra and 72 strictly simultaneous V-band photometric observations for the soft X-ray transient Nova Muscae 1991; the simultaneity is a unique and crucial feature of our study. The mass function and mass ratio of the system are derived from the MagE spectra. We measured the fraction of non-stellar emission from the spectra, which enables us to constrain the disk veiling effect for the light curves. With the veiling-corrected light curves, we have obtained for Nova Muscae 1991 the first accurate estimates of its systemic inclination i = 43.2 (+2.1,-2.7) deg, and black hole mass M = 11.0 (+2.1, -1.4) solar mass. We also found the first clear evidence of the steady optical brightening of Nova Muscae 1991 in X-ray quiescence, which guided us to select light curves that are most suitable for the dynamical modelling.