TY - JOUR
T1 - Accretion of clumpy cold gas onto massive black hole binaries
T2 - A possible fast route to binary coalescence
AU - Goicovic, Felipe G.
AU - Maureira-Fredes, Cristián
AU - Sesana, Alberto
AU - Amaro-Seoane, Pau
AU - Cuadra, Jorge
N1 - Funding Information:
We are grateful to the anonymous referee for a very insightful report that helped improving the clarity of the paper. We also thank Volker Springel for his suggestions on how to improve the conservation of angular momentum of these models, and Johanna Coronado for comments on the manuscript. The simulations were performed partially between the sandy-bridge nodes at HITS, and datura and minerva clusters at the AEI. FGG acknowledges support from CONICYT-Chile through the PCHA Doctorado Nacional scholarship, the Deutscher Akademischer Austauschdienst DAAD (German Academic Exchange service) in the context of the PUC-HD Graduate Exchange Fellowship, the European Research Council under ERC-StG grant EXAGAL-308037, and the Klaus Tschira Foundation. CM-F acknowledges support from the Transregio 7 ‘Gravitational Wave Astronomy’ financed by the Deutsche Forschungsge-meinschaft DFG (German Research Foundation). CM-F acknowledges support from the DFG Project ‘Supermassive black holes, accretion discs, stellar dynamics and tidal disruptions’, awarded to PA-S, and the International Max-Planck Research School. PA-S acknowledges support from the Ramón y Cajal Programme of the Ministry of Economy, Industry and Competitiveness of Spain, as well as the COST Action GWverse CA16104. This work has been partially supported by the CAS President’s International Fellowship Initiative. JC acknowledges support from CONICYT-Chile through FONDECYT (1141175) and Basal (PFB0609) grants. This work was partially developed while JC was on sabbatical leave at MPE. JC and FGG acknowledge the kind hospitality of MPE, and funding from the Max Planck Society through a ‘Partner Group’ grant.
Publisher Copyright:
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2018/9/21
Y1 - 2018/9/21
N2 - In currently favoured hierarchical cosmologies, the formation of massive black hole binaries (MBHBs) following galaxy mergers is unavoidable. Still, due the complex physics governing the (hydro)dynamics of the post-merger dense environment of stars and gas in galactic nuclei, the final fate of those MBHBs is still unclear. In gas-rich environments, it is plausible that turbulence and gravitational instabilities feed gas to the nucleus in the form of a series of cold incoherent clumps, thus providing a way to exchange energy and angular momentum between the MBHB and its surroundings.Within this context, we present a suite of smoothed-particlehydrodynamical models to study the evolution of a sequence of near-radial turbulent gas clouds as they infall towards equal-mass, circular MBHBs.We focus on the dynamical response of the binary orbit to different levels of anisotropy of the incoherent accretion events. Compared to a model extrapolated from a set of individual cloud-MBHB interactions, we find that accretion increases considerably and the binary evolution is faster. This occurs because the continuous infall of clouds drags inwards circumbinary gas left behind by previous accretion events, thus promoting a more effective exchange of angular momentum between the MBHB and the gas. These results suggest that sub-parsec MBHBs efficiently evolve towards coalescence during the interaction with a sequence of individual gas pockets.
AB - In currently favoured hierarchical cosmologies, the formation of massive black hole binaries (MBHBs) following galaxy mergers is unavoidable. Still, due the complex physics governing the (hydro)dynamics of the post-merger dense environment of stars and gas in galactic nuclei, the final fate of those MBHBs is still unclear. In gas-rich environments, it is plausible that turbulence and gravitational instabilities feed gas to the nucleus in the form of a series of cold incoherent clumps, thus providing a way to exchange energy and angular momentum between the MBHB and its surroundings.Within this context, we present a suite of smoothed-particlehydrodynamical models to study the evolution of a sequence of near-radial turbulent gas clouds as they infall towards equal-mass, circular MBHBs.We focus on the dynamical response of the binary orbit to different levels of anisotropy of the incoherent accretion events. Compared to a model extrapolated from a set of individual cloud-MBHB interactions, we find that accretion increases considerably and the binary evolution is faster. This occurs because the continuous infall of clouds drags inwards circumbinary gas left behind by previous accretion events, thus promoting a more effective exchange of angular momentum between the MBHB and the gas. These results suggest that sub-parsec MBHBs efficiently evolve towards coalescence during the interaction with a sequence of individual gas pockets.
KW - Accretion, accretion discs
KW - Black hole physics
KW - Galaxies: evolution
KW - Galaxies: nuclei
KW - Hydrodynamics
UR - http://www.scopus.com/inward/record.url?scp=85051459813&partnerID=8YFLogxK
U2 - 10.1093/mnras/sty1709
DO - 10.1093/mnras/sty1709
M3 - Article
AN - SCOPUS:85051459813
SN - 0035-8711
VL - 479
SP - 3438
EP - 3455
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -