Journal article
THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES
The Astrophysical journal, v 741(2), p103
10 Nov 2011
Abstract
We perform a Bayesian analysis of the mass distribution of stellar-mass black holes using the observed masses of 15 low-mass X-ray binary systems undergoing Roche lobe overflow and 5 high-mass, wind-fed X-ray binary systems. Using Markov Chain Monte Carlo calculations, we model the mass distribution both parametrically-as a power law, exponential, Gaussian, combination of two Gaussians, or log-normal distribution-and non-parametrically-as histograms with varying numbers of bins. We provide confidence bounds on the shape of the mass distribution in the context of each model and compare the models with each other by calculating their relative Bayesian evidence as supported by the measurements, taking into account the number of degrees of freedom of each model. The mass distribution of the low-mass systems is best fit by a power law, while the distribution of the combined sample is best fit by the exponential model. This difference indicates that the low-mass subsample is not consistent with being drawn from the distribution of the combined population. We examine the existence of a "gap" between the most massive neutron stars and the least massive black holes by considering the value, M-1%, of the 1% quantile from each black hole mass distribution as the lower bound of black hole masses. Our analysis generates posterior distributions for M-1%; the best model (the power law) fitted to the low-mass systems has a distribution of lower bounds with M-1% > 4.3 M-circle dot with 90% confidence, while the best model (the exponential) fitted to all 20 systems has M1% > 4.5 M-circle dot with 90% confidence. We conclude that our sample of black hole masses provides strong evidence of a gap between the maximum neutron star mass and the lower bound on black hole masses. Our results on the low-mass sample are in qualitative agreement with those of Ozel et al., although our broad model selection analysis more reliably reveals the best-fit quantitative description of the underlying mass distribution. The results on the combined sample of low-and high-mass systems are in qualitative agreement with Fryer & Kalogera, although the presence of a mass gap remains theoretically unexplained.
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Details
- Title
- THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES
- Creators
- Will M. Farr - Northwestern UniversityNiharika Sravan - Northwestern UniversityAndrew Cantrell - Yale UniversityLaura Kreidberg - Yale UniversityCharles D. Bailyn - Yale UniversityIlya Mandel - Massachusetts Institute of TechnologyVicky Kalogera - Northwestern University
- Publication Details
- The Astrophysical journal, v 741(2), p103
- Publisher
- Iop Publishing Ltd
- Grant note
- PHY-0619274 / NSF MRI; National Science Foundation (NSF); NSF - Office of the Director (OD) AST-0449558; AST-0908930; NSF/AST-0707627 / NSF; National Science Foundation (NSF) AST-0901985 / NSF AAPF; National Science Foundation (NSF); NSF - Directorate for Mathematical & Physical Sciences (MPS)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000296771500036
- Scopus ID
- 2-s2.0-80155187137
- Other Identifier
- 991021877362204721
InCites Highlights
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics