Predicting Stellar-mass Black Hole Populations in Globular Clusters

Newlin C. Weatherford, Sourav Chatterjee, Carl L. Rodriguez, Frederic A. Rasio

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Recent discoveries of black hole (BH) candidates in Galactic and extragalactic globular clusters (GCs) have ignited interest in understanding how BHs dynamically evolve in a GC and the number of BHs (NBH) that may still be retained by todays GCs. Numerical models show that even if stellar-mass BHs are retained in todays GCs, they are typically in configurations that are not directly detectable. We show that a suitably defined measure of mass segregation (Δ) between, e.g., giants and low-mass main-sequence stars, can be an effective probe to indirectly estimate NBH in a GC aided by calibrations from numerical models. Using numerical models, including all relevant physics, we first show that NBH is strongly anticorrelated with Δ between giant stars and low-mass main-sequence stars. We apply the distributions of Δ versus NBH obtained from models to three Milky Way GCs to predict the NBH retained by them at present. We calculate Δ using the publicly available Advanced Camera for Surveys survey data for 47Tuc, M10, and M22, all with identified stellar-mass BH candidates. Using these measured Δ and distributions of Δ versus NBH from models as calibration we predict distributions for NBH expected to be retained in these GCs. For 47Tuc, M10, and M22 our predicted distributions peak at NBH≈20, 24, and 50, whereas, within the 2σ confidence level, NBH can be up to ∼150, 50, and 200, respectively.

Original languageEnglish (US)
Article number13
JournalAstrophysical Journal
Volume864
Issue number1
DOIs
StatePublished - Sep 1 2018

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Keywords

  • M10 M22)
  • globular clusters: general
  • globular clusters: individual (47 Tuc
  • methods: numerical
  • methods: statistical
  • stars: black holes
  • stars: kinematics and dynamics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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