Massive black hole binary mergers within subparsec scale gas discs

By J. Cuadra, Philip Armitage, Richard Alexander, M. Begelman. 2008

313 citations recorded by the source corpus.

We study the efficiency and dynamics of supermassive black hole binary mergers driven by angular momentum loss to small-scale gas discs. Such binaries form after major galaxy mergers, but their fate is unclear since hardening through stellar scattering becomes very inefficient at sub-parsec distances. Gas discs may dominate binary dynamics on these scales, and promote mergers. Using numerical simulations, we investigate the evolution of the semi-major axis and eccentricity of binaries embedded within geometrically thin gas discs. Our simulations directly resolve angular momentum transport within the disc, which at the radii of interest is likely dominated by disc self-gravity. We show that the binary decays at a rate which is in good agreement with analytical estimates, while the eccentricity grows. Saturation of eccentricity growth is not observed up to values e > � 0.35. Accretion onto the black holes is variable, and is roughly modulated by the binary orbital frequency. Scaling our results, we analytically estimate the maximum rate of binary decay that is possible without fragmentation occuring within the surrounding gas disc, and compare that rate to an estimate of the stellar dynamical hardening rate. For binary masses in the range 10 5 M⊙ < � M < � 10 8 M⊙ we find that decay due to gas discs may dominate for separations below a � 10 −2 pc 0.1 pc, in the regime where the disc is optically thick. The minimum merger time scale is shorter than the Hubble time for M < � 10 7 M⊙. This implies that gas discs could commonly attend relatively low mass black hole mergers, and that a significant population of binaries might exist at separations of a few hundredths of a pc, where the combined decay rate is slowest. For more massive binaries, where this mechanism fails to act quickly enough, we suggest that scattering of stars formed within a fragmenting gas disc could act as a significant additional sink of binary angular momentum.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/a3360d0fc564530d2b25d7329e7d75f427d30a7f

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

Citations in the corpus

The astrophysics of nanohertz gravitational waves (2018, methodology): “The approaches in Will (1998), Cutler et al. (2003), and Hazboun et al. (2013) are framed in the context of a null test, in which the assumed observation is the simultaneous arrival, within the margin of error, of some fiducial feature of both the electromagnetic and GW signal.”
Accretion into the central cavity of a circumbinary disc (2012, methodology): “As previous work has shown (Artymowicz & Lubow 1994; Hayasaki et al. 2007; MM08; Cuadra et al. 2009; Roedig et al. 2012; Shi et al. Downloaded from https://academic.oup.com/mnras/article-abstract/436/4/2997/984794 by guest on 26 July 2018 2012), for non-extreme mass ratios, the binary carves out a c”
Assisted inspirals of stellar mass black holes embedded in AGN discs: solving the ‘final au problem’ (2016, methodology): “Snapshots of the disk c© 0000 RAS, MNRAS 000, 000–000 torques have been measured in a few of the above simulations, and suggest that the orbital decay is efficient (MacFadyen & Milosavljević 2008; Cuadra et al. 2009; Roedig et al. 2011; D’Orazio, Haiman & MacFadyen 2013).”
THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC SIMULATIONS OF CIRCUMBINARY ACCRETION DISKS: DISK STRUCTURES AND ANGULAR MOMENTUM TRANSPORT (2011, methodology): “Similar to what was previously found in MM08 and Cuadra et al. (2009), we find the torque density oscillates around zero but damps quickly toward larger distance.”
Black hole mergers: can gas discs solve the ‘final parsec’ problem? (2009, background): “More recently there has been interest in finding an electromagnetic counterpart to the gravitational wave emission expected during the final stages of black hole coalescence (Ivanov et al. 1999; Armitage & Natarajan 2002; Milosavljević & Phinney 2005; Dotti et al. 2006; Loeb2007; Cuadra et al. 2009”
Evolution of binary black holes in self gravitating discs. Dissecting the torques (2012, methodology): “Not surprisingly the disc develops a spiral pattern in the region 3a∼<r∼< 5a, where, in fact, we find that the Toomre parameter reaches its minimum value Q ≈ 1.5 (Cuadra et al. 2009).”
THE POPULATION OF VISCOSITY- AND GRAVITATIONAL WAVE-DRIVEN SUPERMASSIVE BLACK HOLE BINARIES AMONG LUMINOUS ACTIVE GALACTIC NUCLEI (2009, methodology): “It has been shown that the binary–disk interaction could drive both the SMBHs and the gas to have significant eccentricities (Armitage & Natarajan 2005; MacFadyen & Milosavljević 2008; Dotti et al. 2008; Hayasaki et al. 2008; Cuadra et al. 2009).”
Limiting eccentricity of subparsec massive black hole binaries surrounded by self-gravitating gas discs (2011, methodology): “Using high-resolution hydrodynamical simulations, Cuadra et al. (2009) recently investigated the evolution of the orbital elements of a massive BH binary, under the hypotheses that (i) the binary, at the radii of greatest interest (tenths of a parsec), is surrounded C© 2011 The Authors Monthly…”
How do massive black holes get their gas (2009, background): “…reservoirs indeed drive rapid BH–BH coalescence, the rapid merger of the two BHs should be a reasonable assumption on all of the scales that we simulate (see e.g. Escala et al. 2004; Perets, Hopman & Alexander 2007; Mayer et al. 2007; Perets & Alexander 2008; Cuadra et al. 2009; Dotti et al. 2009).”
Tearing up the disc: misaligned accretion on to a binary (2013, background): “Realistic, high-resolution simulations show that a coplanar prograde circumbinary disc is not efficient at shrinking the binary (Cuadra et al. 2009; Lodato et al. 2009).”
BINARY BLACK HOLE ACCRETION FROM A CIRCUMBINARY DISK: GAS DYNAMICS INSIDE THE CENTRAL CAVITY (2013, methodology): “Prior numerical simulations have been performed in 2D (MacFadyen & Milosavljević 2008) (hereafter MM08), (Cuadra et al. 2009; D’Orazio et al. 2012) and in 3D (Hayasaki et al. 2007; Farris et al. 2011, 2012; Noble et al. 2012; Shi et al. 2012; Roedig et al. 2012; Bode et al. 2012; Giacomazzo et al.…”
Doing Science with eLISA: Astrophysics and Cosmology in the Millihertz Regime (2012, background): “nts, and for black holes of mass smaller than about 107 M , gas-dynamical torques on the binary suce to drive the system down to the gravitational wave inspiral domain (Armitage and Natarajan, 2005, Cuadra et al., 2009, Gould and Rix, 2000, Hayasaki et al., 2008, Hayasaki and Okazaki, 2009, Ivanov e”
A LARGE SYSTEMATIC SEARCH FOR CLOSE SUPERMASSIVE BINARY AND RAPIDLY RECOILING BLACK HOLES (2011, unknown): “…of the binary orbit have been explored in an effort to solve this problem, most notably drag by a large gaseous reservoir (e.g. a disk) or torques on a binary at short separations by a circumbinary disk(e.g. Escala et al. 2004; Dotti et al. 2007, 2009b; Cuadra et al. 2009; Lodato et al. 2009).”
The NANOGrav 11 Year Data Set: Pulsar-timing Constraints on the Stochastic Gravitational-wave Background (2018, background): “…et al. 2009; Kocsis & Sesana 2011); (iii) eccentricity, which increases the rate of binary evolution (Peters & Mathews 1963; Peters 1964) and can be amplified by (i) (Sesana et al. 2006; Sesana 2010; Roedig & Sesana 2012) and (ii) (Armitage & Natarajan 2005; Cuadra et al. 2009; Roedig et al. 2011).”
Formation and Evolution of Compact-object Binaries in AGN Disks (2019, background): “Also, when mergers are initially driven by type I/II torque, a significant binary eccentricity is expected to remain at mergers (e.g., Artymowicz et al. 1991; Armitage & Natarajan 2005; Cuadra et al. 2009; Rödig et al. 2011; Fleming & Quinn 2017; Muñoz et al. 2019).”
EFFICIENT MERGER OF BINARY SUPERMASSIVE BLACK HOLES IN MERGING GALAXIES (2011, background): “Of course, this mechanism can act in addition to torques from gas, if present, (e.g. Escala et al. 2005; Dotti et al. 2007; Cuadra et al. 2009), or to loss-cone repopulation due to “massive perturbers” (Perets & Alexander 2008), etc.”