scholarly journals Global torques and stochasticity as the drivers of massive black hole pairing in the young Universe

2020 ◽  
Vol 498 (3) ◽  
pp. 3601-3615 ◽  
Author(s):  
Elisa Bortolas ◽  
Pedro R Capelo ◽  
Tommaso Zana ◽  
Lucio Mayer ◽  
Matteo Bonetti ◽  
...  
Keyword(s):  
Black Hole ◽  
Large Scale ◽  
High Redshift ◽  
Dynamical Evolution ◽  
Dynamical Friction ◽  
Massive Black Hole ◽  
Orbital Decay ◽  
Orbital Phase ◽  
Order Of Magnitude ◽  
Statistical Sample

ABSTRACT The forthcoming Laser Interferometer Space Antenna (LISA) will probe the population of coalescing massive black hole (MBH) binaries up to the onset of structure formation. Here, we simulate the galactic-scale pairing of ∼106 M⊙ MBHs in a typical, non-clumpy main-sequence galaxy embedded in a cosmological environment at z = 7–6. In order to increase our statistical sample, we adopt a strategy that allows us to follow the evolution of six secondary MBHs concomitantly. We find that the magnitude of the dynamical-friction-induced torques is significantly smaller than that of the large-scale, stochastic gravitational torques arising from the perturbed and morphologically evolving galactic disc, suggesting that the standard dynamical friction treatment is inadequate for realistic galaxies at high redshift. The dynamical evolution of MBHs is very stochastic, and a variation in the initial orbital phase can lead to a drastically different time-scale for the inspiral. Most remarkably, the development of a galactic bar in the host system either significantly accelerates the inspiral by dragging a secondary MBH into the centre, or ultimately hinders the orbital decay by scattering the MBH in the galaxy outskirts. The latter occurs more rarely, suggesting that galactic bars overall promote MBH inspiral and binary coalescence. The orbital decay time can be an order of magnitude shorter than what would be predicted relying on dynamical friction alone. The stochasticity and the important role of global torques have crucial implications for the rates of MBH coalescences in the early Universe: both have to be accounted for when making predictions for the upcoming LISA observatory.

scholarly journals Circum-nuclear molecular disks: Role in AGN fueling and feedback

2019 ◽  
Vol 15 (S359) ◽  
pp. 312-317
Author(s):  
Francoise Combes
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
High Resolution ◽  
Large Scale ◽  
Active Galaxy ◽  
Small Scale ◽  
Massive Black Hole ◽  
Molecular Outflows ◽  
Molecular Outflow

AbstractGas fueling AGN (Active Galaxy Nuclei) is now traceable at high-resolution with ALMA (Atacama Large Millimeter Array) and NOEMA (NOrthern Extended Millimeter Array). Dynamical mechanisms are essential to exchange angular momentum and drive the gas to the super-massive black hole. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching 10pc scale (50mas), may bring smoking gun evidence of fueling, within a randomly oriented nuclear gas disk. AGN feedback is also observed, in the form of narrow and collimated molecular outflows, which point towards the radio mode, or entrainment by a radio jet. Precession has been observed in a molecular outflow, indicating the precession of the radio jet. One of the best candidates for precession is the Bardeen-Petterson effect at small scale, which exerts a torque on the accreting material, and produces an extended disk warp. The misalignment between the inner and large-scale disk, enhances the coupling of the AGN feedback, since the jet sweeps a large part of the molecular disk.

scholarly journals Very high redshift quasars and the rapid emergence of super-massive black holes

2020 ◽  
Author(s):  
Pavel Kroupa ◽  
Ladislav Subr ◽  
Tereza Jerabkova ◽  
Long Wang
Keyword(s):  
Black Hole ◽  
Massive Star ◽  
High Redshift ◽  
Host Galaxy ◽  
Massive Black Hole ◽  
First Stars ◽  
Massive Black Holes ◽  
Nuclear Cluster ◽  
Gas Accretion ◽  
Very High

Abstract The observation of quasars at very high redshift such as Pōniuā’ena is a challenge for models of super-massive black hole (SMBH) formation. This work presents a study of SMBH formation via known physical processes in star-burst clusters formed at the onset of the formation of their hosting galaxy. While at the early stages hyper-massive star-burst clusters reach the luminosities of quasars, once their massive stars die, the ensuing gas accretion from the still forming host galaxy compresses its stellar black hole (BH) component to a compact state overcoming heating from the BH–BH binaries such that the cluster collapses, forming a massive SMBH-seed within about a hundred Myr. Within this scenario the SMBH–spheroid correlation emerges near-to-exactly. The highest-redshift quasars may thus be hyper-massive star-burst clusters or young ultra-compact dwarf galaxies (UCDs), being the precursors of the SMBHs that form therein within about 200 Myr of the first stars. For spheroid masses ≲ 109.6 M⊙ a SMBH cannot form and instead only the accumulated nuclear cluster remains. The number evolution of the quasar phases with redshift is calculated and the possible problem of missing quasars at very high redshift is raised. SMBH-bearing UCDs and the formation of spheroids are discussed critically in view of the high redshift observations. A possible tension is found between the high star-formation rates (SFRs) implied by downsizing and the observed SFRs, which may be alleviated within the IGIMF theory and if the downsizing times are somewhat longer.

scholarly journals MASSIVE BLACK HOLE PAIRS IN CLUMPY, SELF-GRAVITATING CIRCUMNUCLEAR DISKS: STOCHASTIC ORBITAL DECAY

2013 ◽  
Vol 777 (1) ◽  
pp. L14 ◽  
Author(s):  
Davide Fiacconi ◽  
Lucio Mayer ◽  
Rok Roškar ◽  
Monica Colpi
Keyword(s):  
Black Hole ◽  
Massive Black Hole ◽  
Orbital Decay

scholarly journals Massive Black Hole Binaries: Dynamical Evolution and Observational Signatures

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
M. Dotti ◽  
A. Sesana ◽  
R. Decarli
Keyword(s):  
Black Hole ◽  
Galaxy Formation ◽  
Dynamical Evolution ◽  
Wave Spectra ◽  
Galaxy Mergers ◽  
Massive Black Hole ◽  
Theoretical Understanding ◽  
Black Hole Binaries ◽  
Recent Developments ◽  
Open Issues

The study of the dynamical evolution of massive black hole pairs in mergers is crucial in the context of a hierarchical galaxy formation scenario. The timescales for the formation and the coalescence of black hole binaries are still poorly constrained, resulting in large uncertainties in the expected rate of massive black hole binaries detectable in the electromagnetic and gravitational wave spectra. Here, we review the current theoretical understanding of the black hole pairing in galaxy mergers, with a particular attention to recent developments and open issues. We conclude with a review of the expected observational signatures of massive binaries and of the candidates discussed in literature to date.

scholarly journals Cosmological simulations of massive black hole seeds: predictions for next-generation electromagnetic and gravitational wave observations

2019 ◽  
Vol 491 (4) ◽  
pp. 4973-4992
Author(s):  
C DeGraf ◽  
D Sijacki
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmic Time ◽  
Host Galaxy ◽  
Electromagnetic Spectrum ◽  
Massive Black Hole ◽  
Cosmological Simulations ◽  
Seed Formation ◽  
Order Of Magnitude ◽  
Low Mass

ABSTRACT We study how statistical properties of supermassive black holes depend on the frequency and conditions for massive seed formation in cosmological simulations of structure formation. We develop a novel method to recalculate detailed growth histories and merger trees of black holes within the framework of the Illustris simulation for several seed formation models, including a physically motivated model where black hole seeds only form in progenitor galaxies that conform to the conditions for direct collapse black hole formation. While all seed models considered here are in a broad agreement with present observational constraints on black hole populations from optical, UV, and X-ray studies, we find that they lead to widely different black hole number densities and halo occupation fractions, which are currently observationally unconstrained. In terms of future electromagnetic spectrum observations, the faint-end quasar luminosity function and the low-mass-end black hole–host galaxy scaling relations are very sensitive to the specific massive seed prescription. Specifically, the direct collapse model exhibits a seeding efficiency that decreases rapidly with cosmic time and produces much fewer black holes in low-mass galaxies, in contrast to the original Illustris simulation. We further find that the total black hole merger rate varies by more than one order of magnitude for different seed models, with the redshift evolution of the chirp mass changing as well. Supermassive black hole merger detections with LISA and International Pulsar Timing Array may hence provide the most direct means of constraining massive black hole seed formation in the early Universe.

scholarly journals Optically faint radio sources: reborn AGN?

2011 ◽  
Vol 7 (S284) ◽  
pp. 231-233
Author(s):  
Mercedes E. Filho ◽  
Jarle Brinchmann ◽  
Catarina Lobo ◽  
Sonia Antón
Keyword(s):  
Black Hole ◽  
Large Scale ◽  
High Redshift ◽  
Radio Sources ◽  
Host Galaxies

AbstractWe have discovered eight relatively strong radio sources that have no optical counterparts. A NIR follow-up has detected faint (17–20 mag) host galaxies in all targets. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with moderate to high redshift (z < 4) GHz-peaked spectrum sources. Our results suggest that these are galaxies whose black hole has been recently re-ignited into activity but that retain large-scale radio structures, signatures of previous AGN activity.

scholarly journals The Role of Gravitational Instabilities in the Feeding of Supermassive Black Holes

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Giuseppe Lodato
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Redshift ◽  
Supermassive Black Holes ◽  
Point Of View ◽  
Accretion Discs ◽  
Theoretical Point ◽  
Interstellar Gas ◽  
Massive Black Hole

I review the recent progresses that have been obtained, especially through the use of high-resolution numerical simulations, on the dynamics of self-gravitating accretion discs. A coherent picture is emerging, where the disc dynamics is controlled by a small number of parameters that determine whether the disc is stable or unstable, whether the instability saturates in a self-regulated state or runs away into fragmentation, and whether the dynamics is local or global. I then apply these concepts to the case of AGN discs, discussing the implications of such evolution on the feeding of supermassive black holes. Nonfragmenting, self-gravitating discs appear to play a fundamental role in the process of formation of massive black hole seeds at high redshift ( 10–15) through direct gas collapse. On the other hand, the different cooling properties of the interstellar gas at low redshifts determine a radically different behaviour for the outskirts of the accretion discs feeding typical AGNs. Here the situation is much less clear from a theoretical point of view, and while several observational clues point to the important role of massive discs at a distance of roughly a parsec from their central black hole, their dynamics is still under debate.

scholarly journals Dynamical self-friction: how mass loss slows you down

2020 ◽  
Vol 495 (4) ◽  
pp. 4496-4507 ◽  
Author(s):  
Tim B Miller ◽  
Frank C van den Bosch ◽  
Sheridan B Green ◽  
Go Ogiya
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Decay Time ◽  
Friction Torque ◽  
Dynamical Friction ◽  
Orbital Parameters ◽  
Orbital Decay ◽  
Order Of Magnitude ◽  
Cent Level

ABSTRACT We investigate dynamical self-friction, the process by which material that is stripped from a subhalo torques its remaining bound remnant, which causes it to lose orbital angular momentum. By running idealized simulations of a subhalo orbiting within an analytical host halo potential, we isolate the effect of self-friction from traditional dynamical friction due to the host halo. While at some points in a subhalo’s orbit the torque of the stripped material can boost the orbital angular momentum of the remnant, the net effect over the long term is orbital decay regardless of the initial orbital parameters or subhalo mass. In order to quantify the strength of self-friction, we run a suite of simulations spanning typical host-to-subhalo mass ratios and orbital parameters. We find that the time-scale for self-friction, defined as the exponential decay time of the subhalo’s orbital angular momentum, scales with mass ratio and orbital circularity similar to standard dynamical friction. The decay time due to self-friction is roughly an order of magnitude longer, suggesting that self-friction only contributes at the 10 per cent level. However, along more radial orbits, self-friction can occasionally dominate over dynamical friction close to pericentric passage, where mass stripping is intense. This is also the epoch at which the self-friction torque undergoes large and rapid changes in both magnitude and direction, indicating that self-friction is an important process to consider when modelling pericentric passages of subhaloes and their associated satellite galaxies.

Sign in / Sign up

Export Citation Format

Share Document