Constraining the mass of Cygnus X-1 using Two Component Advective Flow Solution
Abstract
The galactic black hole candidate Cygnus X-1, one of the brightest sources in the sky, is the first ever black hole candidate to be discovered. Despite being a very well-studied source due to its persistent brightness in X-rays, there has been a lot of difficulty in determining its mass since its discovery. While Bolton (1972) and Paczynski (1974) estimated the lower limit of the mass of the black hole to be ∼ 4 M_⊙, Gies and Bolton (1986) reported that the mass of the compact object should lie in the range 7 M_⊙ to 16 M_⊙. Ninkov et al. (1987) further estimated the mass of the compact object to be 10 ± 1 M_⊙ while according to Herrero et al. (1995) the estimated mass is between 5 M_⊙-15 M_⊙. All these mass measurements are subject to several uncertainties because of the high degree of errors associated with the measurement of the distance. Once Reid et al. (2011) constrained the distance to be ∼ 1.86 kpc, Orosz et al. (2011) provided a stronger constraint on the mass of the BHC in Cygnus X-1 to be M= 14.8 ± 1.0 M_⊙. In this work, we estimate the mass of Cygnus X-1 by analyzing its spectral properties. We use RXTE/PCA archival data and implement the Two Component Advective Flow Solution for spectral analysis. Since mass of the black hole is also an input parameter of the TCAF model, we obtain a constraint on the mass of the black hole from each of the spectral fits. The object exhibits both persistent and flaring behavior and we analyze data during both these phases for constraining the mass of the source. For Cygnus X-1, our estimated mass appears to be M_{avg} = 14.57 ± 0.68 M_⊙ which is consistent with previous estimates reported in the literature.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E.192B