Improved Constraint on the Mass of the Black Hole in Nova Muscae 1991
Abstract
Mass is the fundamental parameter of an astrophysical black hole. An accurate value of mass is a prerequisite for determining a black hole's spin via the continuum-fitting method, while knowledge of both mass and spin completely describes a black hole. Previous dynamical analyses have established that the compact primary in Nova Muscae 1991 (GS 1124-683) is a black hole. In this work, we utilize 72 high resolution Magellan Echelle (MagE) spectra to significantly improve the precision of the mass measurement for Nova Muscae 1991. The spectra were taken on two consecutive nights and span the full 11.4-hour orbital cycle; 70 standard-star template spectra were also taken with the same instrument configuration. The radial velocities of Nova Muscae 1991 are derived by cross-correlating the object spectra with the spectrum of the (K3 V) template star that yielded the statistically most significant cross correlations. Analysis of the data for several echelle orders covering the wavelength range 4100--7300 A provides consistent results for the radial velocity amplitude with a precision of approximately 2 km/s (comparing to ~7 km/s in previous works), which significantly tighten the constraint on the mass function of Nova Muscae 1991.
- Publication:
-
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22332303W