The Pairing Probability of Massive Black Holes in Merger Galaxies in the Presence of Radiative Feedback

Abstract

Dynamical friction (DF) against stars and gas is thought to be an important mechanism for orbital evolution of massive black holes (MBHs) in merger remnant galaxies. Recent theoretical investigations however show that DF does not always lead to MBH inspiral. For MBHs evolving in gas-rich backgrounds, the ionizing radiation that emerges from the innermost parts of their accretion flow can affect the surrounding gas in such a way to cause the MBHs to accelerate and gain orbital energy. This effect was dubbed "negative DF". We use a semi-analytic model to study the impact of negative DF on pairs of MBHs in merger remnant galaxies evolving under the combined influence of stellar and gaseous DF. Our results show that for a wide range of merger galaxy and MBH properties negative DF reduces the MBH pairing probability by $\sim 46\%$. The suppression of MBH pairing is most severe in galaxies with one or more of these properties: (1) a gas fraction of $f_g\ge 0.1$; (2) a galactic gas disk rotating close to the circular velocity; (3) MBH pairs in prograde, low eccentricity orbits, and (4) MBH pairs with mass $<10^8$M${}_{\odot }$. The last point is of importance because MBH pairs in this mass range are direct progenitors of merging binaries targeted by the future space-based gravitational wave observatory LISA.

Accepted for publication to ApJ, 8 pages, 4 figures

References in corpus (7)

• Laser Interferometer Space Antenna
• Massive black hole binary mergers within sub-pc scale gas discs
• Supermassive black hole binaries in gaseous and stellar circumnuclear discs: orbital dynamics and gas accretion
• Dynamical Friction of a Circular-Orbit Perturber in a Gaseous Medium
• The effect of differential accretion on the Gravitational Wave Background and the present day MBH Binary population
• Gaseous dynamical friction under radiative feedback: do intermediate-mass black holes speed up or down?
• Pairing of Massive Black Holes in Merger Galaxies Driven by Dynamical Friction

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• The Detectability of Kiloparsec Scale Dual AGNs: The Impact of Galactic Structure and Black Hole Orbital Properties
• Black hole mergers as tracers of spinning massive black hole and galaxy populations in the OBELISK simulation
• Dynamical friction of a massive black hole in a turbulent gaseous medium
• Astrophysics with the Laser Interferometer Space Antenna
• Tracking on-the-fly massive black hole binary evolution and coalescence in galaxy simulations: RAMCOAL