Low-frequency gravitational radiation from coalescing massive black holes

ABSTRACT The coalescence of massive black hole binaries (BHBs) in galactic mergers is the primary source of gravitational waves (GWs) at low frequencies. Current estimates of GW detection rates for the Laser Interferometer Space Antenna and the Pulsar Timing Array vary by three orders of magnitude. To understand this variation, we simulate the merger of equal-mass, eccentric, galaxy pairs with central massive black holes and shallow inner density cusps. We model the formation and hardening of a central BHB using the fast multiple method as a force solver, which features a O(N) scaling with the number N of particles and obtains results equivalent to direct-summation simulations. At N ∼ 5 × 105, typical for contemporary studies, the eccentricity of the BHBs can vary significantly for different random realizations of the same initial condition, resulting in a substantial variation of the merger time-scale. This scatter owes to the stochasticity of stellar encounters with the BHB and decreases with increasing N. We estimate that N ∼ 107 within the stellar half-light radius suffices to reduce the scatter in the merger time-scale to ∼10 per cent. Our results suggest that at least some of the uncertainty in low-frequency GW rates owes to insufficient numerical resolution.

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Tidal disruption events from massive black hole binaries: predictions for ongoing and future surveys

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1970 ◽

2019 ◽

Vol 488 (3) ◽

pp. 4042-4060 ◽

Cited By ~ 8

Author(s):

Stephen Thorp ◽

Eli Chadwick ◽

Alberto Sesana

Keyword(s):

Black Holes ◽

Black Hole ◽

Low Frequency ◽

Mass Range ◽

Tidal Disruption ◽

Massive Black Hole ◽

Massive Black Holes ◽

X Ray ◽

Black Hole Binaries ◽

Survey Instruments

ABSTRACT We compute the expected cosmic rates of tidal disruption events (TDEs) induced by individual massive black holes (MBHs) and by MBH binaries (MBHBs) – with a specific focus on the latter class – to explore the potential of TDEs to probe the cosmic population of sub-pc MBHBs. Rates are computed by combining MBH and MBHB population models derived from large cosmological simulations with estimates of the induced TDE rates for each class of objects. We construct empirical TDE spectra that fit a large number of observations in the optical, UV, and X-ray and consider their observability by current and future survey instruments. Consistent with results in the literature, and depending on the detailed assumption of the model, we find that LSST and Gaia in optical and eROSITA in X-ray will observe a total of 3000–6000, 80–180, and 600–900 TDEs per year, respectively. Depending on the survey, 1 to several per cent of these are prompted by MBHBs. In particular, both LSST and eROSITA are expected to see 150–450 MBHB-induced TDEs in their respective mission lifetimes, including 5–100 repeated flares. The latter provide an observational sample of binary candidates with relatively low contamination and have the potential of unveiling the sub-pc population of MBHBs in the mass range $10^5\lt M\lt 10^7\, \mathrm{M}_\odot$, thus informing future low-frequency gravitational wave observatories.

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Dancing with Black Holes

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308016141 ◽

2007 ◽

Vol 3 (S246) ◽

pp. 437-446

Author(s):

S. J. Aarseth

Keyword(s):

Black Holes ◽

Gravitational Radiation ◽

Regularization Methods ◽

Stellar Clusters ◽

Massive Black Holes ◽

Large N ◽

Practical Usefulness

AbstractWe describe efforts over the last six years to implement regularization methods suitable for studying one or more interacting black holes by direct N-body simulations. Three different methods have been adapted to large-N systems: (i) Time-Transformed Leapfrog, (ii) Wheel-Spoke, and (iii) Algorithmic Regularization. These methods have been tried out with some success on GRAPE-type computers. Special emphasis has also been devoted to including post-Newtonian terms, with application to moderately massive black holes in stellar clusters. Some examples of simulations leading to coalescence by gravitational radiation will be presented to illustrate the practical usefulness of such methods.

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Birth and life of massive black holes

Uspekhi Fizicheskih Nauk ◽

10.3367/ufnr.0161.199106a.0001 ◽

1991 ◽

Vol 161 (6) ◽

pp. 1 ◽

Cited By ~ 10

Author(s):

V.I. Dokuchaev

Keyword(s):

Black Holes ◽

Massive Black Holes

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Collisional Stellar Dynamics around Massive Black Holes in Active Galactic Nuclei

The Astrophysical Journal ◽

10.1086/306953 ◽

1999 ◽

Vol 514 (2) ◽

pp. 725-745 ◽

Cited By ~ 22

Author(s):

Kevin P. Rauch

Keyword(s):

Black Holes ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Stellar Dynamics ◽

Massive Black Holes

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X-ray properties of reverberation-mapped AGNs with super-Eddington accreting massive black holes

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002756 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 143-143

Author(s):

Jaya Maithil ◽

Michael S. Brotherton ◽

Bin Luo ◽

Ohad Shemmer ◽

Sarah C. Gallagher ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Accretion Rate ◽

Time Lags ◽

Black Hole Mass ◽

Host Galaxies ◽

Massive Black Holes ◽

X Ray ◽

Photon Index ◽

The Impact

AbstractActive Galactic Nuclei (AGN) exhibit multi-wavelength properties that are representative of the underlying physical processes taking place in the vicinity of the accreting supermassive black hole. The black hole mass and the accretion rate are fundamental for understanding the growth of black holes, their evolution, and the impact on the host galaxies. Recent results on reverberation-mapped AGNs show that the highest accretion rate objects have systematic shorter time-lags. These super-Eddington accreting massive black holes (SEAMBHs) show BLR size 3-8 times smaller than predicted by the Radius-Luminosity (R-L) relationship. Hence, the single-epoch virial black hole mass estimates of highly accreting AGNs have an overestimation of a factor of 3-8 times. SEAMBHs likely have a slim accretion disk rather than a thin disk that is diagnostic in X-ray. I will present the extreme X-ray properties of a sample of dozen of SEAMBHs. They indeed have a steep hard X-ray photon index, Γ, and demonstrate a steeper power-law slope, ασx.

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Gaseous Disks in the Nuclei of Elliptical Galaxies

International Astronomical Union Colloquium ◽

10.1017/s0252921100043293 ◽

1997 ◽

Vol 163 ◽

pp. 620-625 ◽

Cited By ~ 4

Author(s):

H. Ford ◽

Z. Tsvetanov ◽

L. Ferrarese ◽

G. Kriss ◽

W. Jaffe ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Accretion Disks ◽

Large Scale ◽

Elliptical Galaxies ◽

Central Mass ◽

Massive Black Holes ◽

Radio Jets

AbstractHST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.

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