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Title: THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES

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{sub 1%}, of the 1% quantile from each black hole mass distribution as the lower boundmore » of black hole masses. Our analysis generates posterior distributions for M{sub 1%}; the best model (the power law) fitted to the low-mass systems has a distribution of lower bounds with M{sub 1%}>4.3 M{sub sun} with 90% confidence, while the best model (the exponential) fitted to all 20 systems has M{sub 1%}>4.5 M{sub sun} 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 and Kalogera, although the presence of a mass gap remains theoretically unexplained.« less

Authors:
; ;  [1]; ; ;  [2];  [3]
  1. Northwestern University Center for Interdisciplinary Exploration and Research in Astrophysics, 2145 Sheridan Rd., Evanston, IL 60208 (United States)
  2. Department of Astrophysics, Yale University, P. O. Box 208101, New Haven, CT 06520 (United States)
  3. Kavli Institute, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
Publication Date:
OSTI Identifier:
21612683
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 741; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/741/2/103; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; DATA ANALYSIS; DEGREES OF FREEDOM; MARKOV PROCESS; MASS DISTRIBUTION; MONTE CARLO METHOD; NEUTRON STARS; ROCHE EQUIPOTENTIALS; CALCULATION METHODS; DISTRIBUTION; POTENTIALS; SPATIAL DISTRIBUTION; STARS; STOCHASTIC PROCESSES

Citation Formats

Farr, Will M, Sravan, Niharika, Kalogera, Vicky, Cantrell, Andrew, Kreidberg, Laura, Bailyn, Charles D, and Mandel, Ilya. THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES. United States: N. p., 2011. Web. doi:10.1088/0004-637X/741/2/103; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Farr, Will M, Sravan, Niharika, Kalogera, Vicky, Cantrell, Andrew, Kreidberg, Laura, Bailyn, Charles D, & Mandel, Ilya. THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES. United States. https://doi.org/10.1088/0004-637X/741/2/103; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)
Farr, Will M, Sravan, Niharika, Kalogera, Vicky, Cantrell, Andrew, Kreidberg, Laura, Bailyn, Charles D, and Mandel, Ilya. 2011. "THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES". United States. https://doi.org/10.1088/0004-637X/741/2/103; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21612683,
title = {THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES},
author = {Farr, Will M and Sravan, Niharika and Kalogera, Vicky and Cantrell, Andrew and Kreidberg, Laura and Bailyn, Charles D and Mandel, Ilya},
abstractNote = {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{sub 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{sub 1%}; the best model (the power law) fitted to the low-mass systems has a distribution of lower bounds with M{sub 1%}>4.3 M{sub sun} with 90% confidence, while the best model (the exponential) fitted to all 20 systems has M{sub 1%}>4.5 M{sub sun} 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 and Kalogera, although the presence of a mass gap remains theoretically unexplained.},
doi = {10.1088/0004-637X/741/2/103; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
url = {https://www.osti.gov/biblio/21612683}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 741,
place = {United States},
year = {Thu Nov 10 00:00:00 EST 2011},
month = {Thu Nov 10 00:00:00 EST 2011}
}