Gravitational wave quasinormal mode from Population III massive black hole binaries in various models of population synthesis

ABSTRACT The existence of massive stellar black hole binaries (MBHBs), with primary black hole masses $\ge 31 \, \mathrm{ M}_\odot$, was proven by the detection of the gravitational wave (GW) event GW150914 during the first LIGO/Virgo observing run (O1), and successively confirmed by seven additional GW signals discovered in the O1 and O2 data. By adopting the galaxy formation model gamesh coupled with binary population synthesis (BPS) calculations, here we investigate the origin of these MBHBs by selecting simulated binaries compatible in mass and coalescence redshifts. We find that their cosmic birth rates peak in the redshift range 6.5 ≤ z ≤ 10, regardless of the adopted BPS. These MBHBs are then old systems forming in low-metallicity ($Z \sim [0.01\!-\!0.1] \, Z_{\odot }$), low-stellar-mass galaxies, before the end of cosmic reionization, i.e. significantly beyond the peak of cosmic star formation. GW signals generated by coalescing MBHBs open up new possibilities to probe the nature of stellar populations in remote galaxies, at present too faint to be detected by available electromagnetic facilities.

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The nightmare scenario: measuring the stochastic gravitational wave background from stalling massive black hole binaries with pulsar timing arrays

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stx1454 ◽

2017 ◽

Vol 470 (4) ◽

pp. 4547-4556 ◽

Cited By ~ 21

Author(s):

Irina Dvorkin ◽

Enrico Barausse

Keyword(s):

Black Hole ◽

Gravitational Wave ◽

Massive Black Hole ◽

Black Hole Binaries ◽

Pulsar Timing ◽

Gravitational Wave Background

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Formation of counter-rotating and highly eccentric massive black hole binaries in galaxy mergers

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab351 ◽

2021 ◽

Vol 503 (1) ◽

pp. 498-510

Author(s):

Imran Tariq Nasim ◽

Cristobal Petrovich ◽

Adam Nasim ◽

Fani Dosopoulou ◽

Fabio Antonini

Keyword(s):

Black Hole ◽

Gravitational Wave ◽

Dynamical Evolution ◽

Orbital Plane ◽

Equal Mass ◽

Galaxy Mergers ◽

High Eccentricity ◽

Massive Black Hole ◽

Black Hole Binaries ◽

Binary Evolution

ABSTRACT Supermassive black hole (SMBH) binaries represent the main target for missions such as the Laser Interferometer Space Antenna and Pulsar Timing Arrays. The understanding of their dynamical evolution prior to coalescence is therefore crucial to improving detection strategies and for the astrophysical interpretation of the gravitational wave data. In this paper, we use high-resolution N-body simulations to model the merger of two equal-mass galaxies hosting a central SMBH. In our models, all binaries are initially prograde with respect to the galaxy sense of rotation. But, binaries that form with a high eccentricity, e ≳ 0.7, quickly reverse their sense of rotation and become almost perfectly retrograde at the moment of binary formation. The evolution of these binaries proceeds towards larger eccentricities, as expected for a binary hardening in a counter-rotating stellar distribution. Binaries that form with lower eccentricities remain prograde and at comparatively low eccentricities. We study the origin of the orbital flip by using an analytical model that describes the early stages of binary evolution. This model indicates that the orbital plane flip is due to the torque from the triaxial background mass distribution that naturally arises from the galactic merger process. Our results imply the existence of a population of SMBH binaries with a high eccentricity and could have significant implications for the detection of the gravitational wave signal emitted by these systems.

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