scholarly journals Massive black hole binary systems and the NANOGrav 12.5 yr results

2021 ◽  
Vol 502 (1) ◽  
pp. L99-L103
Author(s):  
H Middleton ◽  
A Sesana ◽  
S Chen ◽  
A Vecchio ◽  
W Del Pozzo ◽  
...  
Keyword(s):  
Black Hole ◽  
Binary Systems ◽  
Large Population ◽  
Theoretical Models ◽  
Observational Result ◽  
Massive Black Hole ◽  
Stochastic Signal ◽  
The North ◽  
Credible Intervals ◽  
Merger Rate

ABSTRACT The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) recently reported evidence for the presence of a common stochastic signal across their array of pulsars. The origin of this signal is still unclear. One possibility is that it is due to a stochastic gravitational-wave background (SGWB) in the ∼1–10 nHz frequency region. Taking the NANOGrav observational result at face value, we show that this signal would be fully consistent with an SGWB produced by an unresolved population of in-spiralling massive black hole binaries (MBHBs) predicted by current theoretical models. Considering an astrophysically agnostic model, the MBHB merger rate is loosely constrained. Including additional constraints from galaxy pairing fraction and MBH–bulge scaling relations, we find that the MBHB merger rate is ${1.2\times 10^{-5}}{\rm -}{4.5\times 10^{-4}}\, \mathrm{Mpc}^{-3}\, \mathrm{Gyr}^{-1}$ , the MBHB merger time-scale is $\le 2.7\, \mathrm{Gyr}$, and the norm of the MBH−Mbulge relation is $\ge 1.2\times 10^{8}\, {\rm M}_\odot$ (all quoted at 90 per  cent credible intervals). Regardless of the astrophysical details of MBHB assembly, the NANOGrav result would imply that a sufficiently large population of massive black holes pair up, form binaries and merge within a Hubble time.

scholarly journals MASSIVE BLACK HOLE BINARY SYSTEMS IN HIERARCHIAL SCENARIO OF STRUCTURE FORMATION

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1271-1274
Author(s):  
E. S. PEREIRA ◽  
O. D. MIRANDA
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Structure Formation ◽  
Binary Systems ◽  
Initial Study ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
The Press ◽  
Future Extension ◽  
Merger Rate

The hierarchical scenario of structure formation describes how objects like galaxies and galaxy clusters are formed by mergers of small objects. In this scenario, mergers of galaxies can lead to the formation of massive black hole (MBH) binary systems. On the other hand, the merger of two MBH could produce a gravitational wave signal detectable, in principle, by the Laser Interferometer Space Antenna (LISA). In the present work, we use the Press–Schechter formalism, and its extension, to describe the merger rate of haloes which contain massive black holes. Here, we do not study the gravitational wave emission of these systems. However, we present an initial study to determine the number of systems formed via mergers that could permit, in a future extension of this work, the calculation of the signature in gravitational waves of these systems.

Early Observations of Black Holes

2020 ◽  
pp. 58-71
Author(s):  
John W. Moffat
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Event Horizon ◽  
Binary Systems ◽  
Theoretical Models ◽  
Supermassive Black Holes ◽  
Spectral Lines ◽  
Current Evidence ◽  
X Rays ◽  
Electromagnetic Processes

Early observations of black holes, before the LIGO/Virgo detection of gravitational waves, were made by observing electromagnetic processes involving atomic spectral lines. X-ray binary systems were observed consisting of a progenitor star such as a neutron star and a dark companion. X-rays emitted from the gas accreting the dark companion tells us whether it is a black hole. Evidence indicated supermassive black holes at the centers of galaxies. From observations of orbits of stars near the supermassive black holes, one could determine their masses, which proved they were black holes. Observations of quasars, among the brightest objects in the universe, showed they contain black holes. It is important to establish the existence of an event horizon with the black hole, as predicted by general relativity. The current evidence for the event horizon is circumstantial, based on controversial theoretical models about the accretion disks surrounding the collapsed dark objects.

scholarly journals Black hole mergers from dwarf to massive galaxies with the NewHorizon and Horizon-AGN simulations

2020 ◽  
Vol 498 (2) ◽  
pp. 2219-2238 ◽  
Author(s):  
Marta Volonteri ◽  
Hugo Pfister ◽  
Ricarda S Beckmann ◽  
Yohan Dubois ◽  
Monica Colpi ◽  
...  
Keyword(s):  
Black Hole ◽  
Time Delays ◽  
Large Scale ◽  
Low Frequency ◽  
High Mass ◽  
Massive Black Hole ◽  
Statistical Population ◽  
The Galaxy ◽  
Low Mass ◽  
Merger Rate

ABSTRACT Massive black hole (MBH) coalescences are powerful sources of low-frequency gravitational waves. To study these events in the cosmological context, we need to trace the large-scale structure and cosmic evolution of a statistical population of galaxies, from dim dwarfs to bright galaxies. To cover such a large range of galaxy masses, we analyse two complementary simulations: horizon-AGN with a large volume and low resolution that tracks the high-mass ($\gt 10^7\, {\rm M_\odot }$) MBH population, and NewHorizon with a smaller volume but higher resolution that traces the low-mass ( $\lt 10^7\, {\rm M_\odot }$) MBH population. While Horizon-AGN can be used to estimate the rate of inspirals for pulsar timing arrays, NewHorizon can investigate MBH mergers in a statistical sample of dwarf galaxies for LISA, which is sensitive to low-mass MBHs. We use the same method to analyse the two simulations, post-processing MBH dynamics to account for time delays mostly determined by dynamical friction and stellar hardening. In both simulations, MBHs typically merge long after galaxies do, so that the galaxy morphology at the time of the MBH merger is no longer determined by the structural disturbances engendered by the galaxy merger from which the MBH coalescence has originated. These time delays cause a loss of high-z MBH coalescences, shifting the peak of the MBH merger rate to z ∼ 1–2. This study shows how tracking MBH mergers in low-mass galaxies is crucial to probing the MBH merger rate for LISA and investigate the properties of the host galaxies.

scholarly journals A self-lensing binary massive black hole interpretation of quasi-periodic eruptions

2021 ◽  
Vol 503 (2) ◽  
pp. 1703-1716
Author(s):  
Adam Ingram ◽  
Sara E Motta ◽  
Suzanne Aigrain ◽  
Aris Karastergiou
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Binary Systems ◽  
Galactic Nuclei ◽  
Galaxy Mergers ◽  
Massive Black Hole ◽  
X Ray ◽  
Binary Separation ◽  
Low Mass ◽  
Optical Time

ABSTRACT Binary supermassive black hole (SMBH) systems result from galaxy mergers, and will eventually coalesce due to gravitational wave (GW) emission if the binary separation can be reduced to ≲0.1 pc by other mechanisms. Here, we explore a gravitational self-lensing binary SMBH model for the sharp (duration ∼1 h), quasi-regular X-ray flares – dubbed quasi-periodic eruptions – recently observed from two low-mass active galactic nuclei: GSN 069 and RX J1301.9+2747. In our model, the binary is observed ∼edge-on, such that each SMBH gravitationally lenses light from the accretion disc surrounding the other SMBH twice per orbital period. The model can reproduce the flare spacings if the current eccentricity of RX J1301.9+2747 is ϵ0 ≳ 0.16, implying a merger within ∼1000 yr. However, we cannot reproduce the observed flare profiles with our current calculations. Model flares with the correct amplitude are ∼2/5 the observed duration, and model flares with the correct duration are ∼2/5 the observed amplitude. Our modelling yields three distinct behaviours of self-lensing binary systems that can be searched for in current and future X-ray and optical time-domain surveys: (i) periodic lensing flares, (ii) partial eclipses (caused by occultation of the background mini-disc by the foreground mini-disc), and (iii) partial eclipses with a very sharp in-eclipse lensing flare. Discovery of such features would constitute very strong evidence for the presence of a supermassive binary, and monitoring of the flare spacings will provide a measurement of periastron precession.

scholarly journals X-Ray Evidence Against the Hypothesis that the Hyperluminous z = 6.3 Quasar J0100+2802 is Lensed

2021 ◽  
Vol 922 (2) ◽  
pp. L24
Author(s):  
Thomas Connor ◽  
Daniel Stern ◽  
Eduardo Bañados ◽  
Chiara Mazzucchelli
Keyword(s):  
Black Hole ◽  
High Resolution ◽  
Rest Frame ◽  
Theoretical Models ◽  
Spectral Features ◽  
Massive Black Hole ◽  
Underlying Distribution ◽  
X Ray ◽  
Black Hole Masses ◽  
The Universe

Abstract The z = 6.327 quasar SDSS J010013.02+280225.8 (hereafter J0100+2802) is believed to be powered by a black hole more massive than 1010 M ⊙, making it the most massive black hole known in the first billion years of the universe. However, recent high-resolution ALMA imaging shows four structures at the location of this quasar, potentially implying that it is lensed with a magnification of μ ∼ 450 and thus its black hole is significantly less massive. Furthermore, for the underlying distribution of magnifications of z ≳ 6 quasars to produce such an extreme value, theoretical models predict that a larger number of quasars in this epoch should be lensed, implying further overestimates of early black hole masses. To provide an independent constraint on the possibility that J0100+2802 is lensed, we reanalyzed archival XMM-Newton observations of the quasar and compared the expected ratios of X-ray luminosity to rest-frame UV and IR luminosities. For both cases, J0100+2802's X-ray flux is consistent with the no-lensing scenario; while this could be explained by J0100+2802 being X-ray faint, we find it does not have the X-ray or optical spectral features expected for an X-ray faint quasar. Finally, we compare the overall distribution of X-ray fluxes for known, typical z ≳ 6 quasars. We find a 3σ tension between the observed and predicted X-ray-to-UV flux ratios when adopting the magnification probability distribution required to produce a μ = 450 quasar.

Sign in / Sign up

Export Citation Format

Share Document