scholarly journals Mass-ratio and Magnetic Flux Dependence of Modulated Accretion from Circumbinary Disks

2021 ◽  
Vol 922 (2) ◽  
pp. 175
Author(s):  
Scott C. Noble ◽  
Julian H. Krolik ◽  
Manuela Campanelli ◽  
Yosef Zlochower ◽  
Bruno C. Mundim ◽  
...  
Keyword(s):  
Black Holes ◽  
Magnetic Flux ◽  
Internal Stress ◽  
Light Output ◽  
Threshold Value ◽  
Periodic Signal ◽  
Mass Ratio ◽  
Binary Black Holes ◽  
Accretion Flow ◽  
Forming Simulations

Abstract Accreting supermassive binary black holes (SMBBHs) are potential multimessenger sources because they emit both gravitational-wave and electromagnetic (EM) radiation. Past work has shown that their EM output may be periodically modulated by an asymmetric density distribution in the circumbinary disk, often called an “overdensity” or “lump;” this modulation could possibly be used to identify a source as a binary. We explore the sensitivity of the overdensity to SMBBH mass ratio and magnetic flux through the accretion disk. We find that the relative amplitude of the overdensity and its associated EM periodic signal both degrade with diminishing mass ratio, vanishing altogether somewhere between 1:2 and 1:5. Greater magnetization also weakens the lump and any modulation of the light output. We develop a model to describe how lump formation results from internal stress degrading faster in the lump region than it can be rejuvenated through accretion inflow, and predicts a threshold value in specific internal stress below which lump formation should occur and which all our lump-forming simulations satisfy. Thus, detection of such a modulation would provide a constraint on both mass ratio and magnetic flux piercing the accretion flow.

scholarly journals Do floating orbits in extreme mass ratio binary black holes exist?

2013 ◽  
Vol 87 (4) ◽  
Author(s):  
Shasvath J. Kapadia ◽  
Daniel Kennefick ◽  
Kostas Glampedakis
Keyword(s):  
Black Holes ◽  
Mass Ratio ◽  
Binary Black Holes

scholarly journals Common Envelope Wind Tunnel: The Effects of Binary Mass Ratio and Implications for the Accretion-driven Growth of LIGO Binary Black Holes

2020 ◽  
Vol 897 (2) ◽  
pp. 130 ◽  
Author(s):  
Soumi De ◽  
Morgan MacLeod ◽  
Rosa Wallace Everson ◽  
Andrea Antoni ◽  
Ilya Mandel ◽  
...  
Keyword(s):  
Black Holes ◽  
Wind Tunnel ◽  
Mass Ratio ◽  
Binary Black Holes ◽  
Common Envelope

scholarly journals Merging of unequal mass binary black holes in non-axisymmetric galactic nuclei

2014 ◽  
Vol 10 (S312) ◽  
pp. 82-85
Author(s):  
Peter Berczik ◽  
Long Wang ◽  
Keigo Nitadori ◽  
Rainer Spurzem
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Galactic Nuclei ◽  
Hardware Acceleration ◽  
Galaxy Mergers ◽  
Mass Ratio ◽  
Graphic Processing Units ◽  
Massive Black Hole ◽  
Binary Black Holes ◽  
Unequal Mass

AbstractIn this work we study the stellar-dynamical hardening of unequal mass massive black hole (MBH) binaries in the central regions of galactic nuclei. We present a comprehensive set of direct N-body simulations of the problem, varying both the total mass and the mass ratio of the MBH binary. Our initial model starts as an axisymmetric, rotating galactic nucleus, to describe the situation right after the galaxies have merged, but the black holes are still unbound to each other. We confirm that results presented in earlier works (Berczik et al. 2006; Khan et al. 2013; Wang et al. 2014) about the solution of the “last parsec problem” (sufficiently fast black hole coalescence for black hole growth in cosmological context) are robust for both for the case of unequal black hole masses and large particle numbers. The MBH binary hardening rate depends on the reduced mass ratio through a single parameter function, which quantitatively quite well agrees with standard 3 body scattering theory (see e.g., Hills 1983). Based on our results we conclude that MBH binaries at high redshifts are expected to merge with a factor of ~ 2 more efficiently, which is important to determine the possible overall gravitational wave signals. However, we have not yet fully covered all the possible parameter space, in particular with respect to the preceding of the galaxy mergers, which may lead to a wider variety of initial models, such as initially more oblate and / or even significantly triaxial galactic nuclei. Our N-body simulations were carried out on a new special supercomputers using the hardware acceleration with graphic processing units (GPUs).

Close binary black hole in a radio-quiet quasar: a candidate of Nano-Hertz gravitational wave emitter

2021 ◽  
Author(s):  
Hai-Cheng Feng ◽  
Hong-Tao Liu ◽  
Jinming Bai
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Close Binary ◽  
Wave Radiation ◽  
Periodic Signal ◽  
Binary Black Holes ◽  
Binary Black Hole ◽  
Line Region ◽  
Small Ratio ◽  
Region Size

Abstract Close supermassive binary black holes (SMBBHs) with separations less than about 0.1 parsec are expected to be Nano-Hertz gravitational wave sources. SMBBH systems should exhibit periodic variability. However, periodic variability in radio-loud quasars may be interpreted with the jet model. Here we report the detection of a robust periodic signal in the optical variability of the radio-quiet quasar PG 0923+201 with an observed period of 726.8±4.7 days, obtained from the sinusoid-like light curve of a temporal baseline of about 9 years. This periodicity is probably from a close SMBBH with a total mass of 109.3 solar masses and a separation of about 0.01 parsec, implying relativistic orbital speeds. Such a system has passed through the well-known “final parsec problem” of SMBBH systems, and the Nano-Hertz gravitational wave radiation becomes significant. The ratio of the separation between these two black holes to the broad-line region size is about 0.1. A close SMBBH is also suggested by this small ratio and the spectral properties of Balmer broad lines in this quasar. This radio-quiet quasar is a candidate emitter of Nano-Hertz gravitational waves at a frequency of about 30 Nano-Hertz.

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