Growing massive black holes in a Local Group environment: The central supermassive, slowly sinking and ejected populations

Miroslav Micic, Kelly Holley-Bockelmann, Steinn Sigurdsson

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


We explore the growth of ≤107M black holes that reside at the centres of spiral and field dwarf galaxies in a Local Group type of environment. We use merger trees from a cosmological N-body simulation known as Via Lactea 2 (VL-2) as a framework to test two merger-driven semi-analytic recipes for black hole growth that include dynamical friction, tidal stripping and gravitational wave recoil in over 20000 merger tree realizations. First, we apply a Fundamental Plane limited (FPL) model to the growth of SgrA*, which drives the central black hole to a maximum mass limited by the black hole Fundamental Plane after every merger. Next, we present a new model that allows for low-level prolonged gas accretion (PGA) during the merger. We find that both models can generate an SgrA* mass black hole. We predict a population of massive black holes in local field dwarf galaxies - if the VL-2 simulation is representative of the growth of the Local Group, we predict up to 35 massive black holes (≤106M) in Local Group field dwarfs. We also predict that hundreds of ≤105M black holes fail to merge, and instead populate the Milky Way halo, with the most massive of them at roughly the virial radius. In addition, we find that there may be hundreds of massive black holes ejected from their hosts into the nearby intergalactic medium due to gravitational wave recoil. We discuss how the black hole population in the Local Group field dwarfs may help to constrain the growth mechanism for SgrA*.

Original languageEnglish (US)
Pages (from-to)1127-1144
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Jun 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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