Accretion during the Merger of Supermassive Black Holes

Abstract

We study the evolution of disk accretion during the merger of supermassive black hole binaries in galactic nuclei. In hierarchical galaxy formation models, the most common binaries are likely to arise from minor galactic mergers, and have unequal mass black holes. Once such a binary becomes embedded in an accretion disk at a separation a ∼ 0.1 pc, the merger proceeds in two distinct phases. During the first phase, the loss of orbital angular momentum to the gaseous disk shrinks the binary on a timescale of ∼ 10 7 yr. The accretion rate onto the primary black hole is not increased, and can be substantially reduced, during this disk-driven migration. At smaller separations, gravitational radiation becomes the dominant angular momentum loss process, and any gas trapped inside the orbit of the secondary is driven inwards by the inspiralling black hole. The implied accretion rate just prior to coalescence exceeds the Eddington limit, so the final merger is likely to occur within a common envelope formed from the disrupted inner disk, and be accompanied by high velocity (∼ 10 4 kms −1 ) outflows.

Cosmological physics with black holes (and possibly white dwarfs)

“…Indeed, one can use near real-time GW information on the sky localization, in combination with the accurate timing of the inspiral event, to predetermine well in advance where on the sky the merger is located. A unique host galaxy identification could then proceed through coordinated observations with traditional telescopes, by monitoring in real time the sky area for unusual electromagnetic emission, as A variety of mechanisms exist through which disturbed gas in the vicinity of black hole pairs will power electromagnetic emission during and after coalescence (Armitage & Natarajan, 2002;Milosavljevic & Phinney, 2005;Dotti et al, 2006;Bode & Phinney, 2007;MacFadyen & Milosavljevic, 2008). For example, at the time of coalescence, ∼ > 10 53 ergs of kinetic energy are delivered to the recoiling black hole remnant and its environment, for typical recoil velocities ∼ > 100 km/s (e.g., Baker et al, 2006Baker et al, , 2007Campanelli et al, 2007;Herrmann et al, 2007;Schnittman & Buonanno, 2007).…”

Evolution of binary black holes in self gravitating discs

“…More recently, the techniques adopted in these fields have been applied to the BHB case. In the last decade, several investigations were devoted to the study of comparable mass BHBs evolving in circumbinary discs, exploiting a variety of analytical and numerical techniques (Ivanov et al 1999;Armitage & Natarajan 2002, 2005Hayasaki et al 2007Hayasaki et al , 2008MacFadyen & Milosavljević 2008;Hayasaki 2009;Cuadra et al 2009;Lodato et al 2009;Nixon et al 2011;Roedig et al 2011;Shi et al 2012). However only few of them focused on the details of the dynamical disc-binary interplay.…”

Electromagnetic counterparts of recoiling black holes: general relativistic simulations of non-Keplerian discs

“…A&A 523, A8 (2010) As a product of this increased interest, a number of studies have been recently carried out to investigate the properties of these EM counterparts either during the stages that precede the merger, or in those following it. As an example, recent work has considered the interaction between the binary and a dense gas cloud (Armitage & Natarajan 2002;van Meter et al 2010;Bode et al 2009;Farris et al 2010;Lodato et al 2009;Chang et al 2010) even though astrophysical considerations seem to suggest that during the very final stages of the merger the SMBBH will inspiral in a rather tenuous intergalactic medium. At the same time, other scenarios not involving matter have also been considered.…”