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Massive binary star mergers in galactic nuclei: implications for blue stragglers, binary S-stars and gravitational waves

Fragione, Giacomo and Antonini, Fabio (2019) Massive binary star mergers in galactic nuclei: implications for blue stragglers, binary S-stars and gravitational waves Monthly Notices of the Royal Astronomical Society, stz1723.

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Abstract

Galactic nuclei are often found to contain young stellar populations and, in most cases, a central supermassive black hole (SMBH). Most known massive stars are found in binaries or higher-multiplicity systems, and in a galactic nucleus the gravitational interaction with the SMBH can affect their long-term evolution. In this paper, we study the orbital evolution of stellar binaries near SMBHs using high precision N-body simulations, and including tidal forces and Post-Newtonian corrections to the motion. We focus on the Lidov-Kozai (LK) effect induced by the SMBH on massive star binaries. We investigate how the properties of the merging binaries change with varying the SMBH mass, the slope of the initial mass function, the distributions of the binary orbital parameters and the efficiency in energy dissipation in dissipative tides. We find that the fraction of merging massive binary stars is in the range ∼4%–15% regardless of the details of the initial distributions of masses and orbital elements. For a Milky Way-like nucleus, we find a typical rate of binary mergers Γ≈1.4×10−7yr−1⁠. The merger products of massive binaries can be rejuvenated blue-straggler stars, more massive than each of their original progenitors, and G2-like objects. Binary systems that survive the LK cycles can be source of X-rays and gravitational waves, observable with present and upcoming instruments.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
NameEmailORCID
Fragione, Giacomo
Antonini, Fabiof.antonini@surrey.ac.uk
Date : 21 June 2019
Funders : Science and Technology Facilities Council (STFC)
DOI : 10.1093/mnras/stz1723
Copyright Disclaimer : © 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record (Giacomo Fragione, Fabio Antonini, 'Massive binary star mergers in galactic nuclei: implications for blue stragglers, binary S-stars and gravitational waves', Monthly Notices of the Royal Astronomical Society, stz1723, https://doi.org/10.1093/mnras/stz1723) is available online at: https://doi.org/10.1093/mnras/stz1723 .
Uncontrolled Keywords : Galaxy: centre. Galaxy: kinematics and dynamics. Stars: kinematics and dynamics. Galaxies: star clusters: general. Stars: black holes. Stars: neutron.
Depositing User : Clive Harris
Date Deposited : 26 Jun 2019 08:24
Last Modified : 26 Jun 2019 08:24
URI: http://epubs.surrey.ac.uk/id/eprint/852085

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