scholarly journals Stellar hardening of massive black hole binaries: the impact of the host rotation

2021 ◽  
Vol 508 (1) ◽  
pp. 1533-1542
Author(s):  
Ludovica Varisco ◽  
Elisa Bortolas ◽  
Massimo Dotti ◽  
Alberto Sesana
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Equal Mass ◽  
Stellar Systems ◽  
Massive Black Hole ◽  
Loss Cone ◽  
Black Hole Binaries ◽  
Influence Radius ◽  
Three Body ◽  
The Impact

ABSTRACT Massive black hole binaries (MBHBs) with masses of ∼104 to $\sim 10^{10} \, \mathrm{M}_{\odot {}}$ are one of the main targets for currently operating and forthcoming space-borne gravitational wave observatories. In this paper, we explore the effect of the stellar host rotation on the bound binary hardening efficiency, driven by three-body stellar interactions. As seen in previous studies, we find that the centre of mass (CoM) of a prograde MBHB embedded in a rotating environment starts moving on a nearly circular orbit about the centre of the system shortly after the MBHB binding. In our runs, the oscillation radius is ≈ 0.25 (≈ 0.1) times the binary influence radius for equal mass MBHBs (MBHBs with mass ratio 1:4). Conversely, retrograde binaries remain anchored about the centre of the host. The binary shrinking rate is twice as fast when the binary CoM exhibits a net orbital motion, owing to a more efficient loss cone repopulation even in our spherical stellar systems. We develop a model that captures the CoM oscillations of prograde binaries; we argue that the CoM angular momentum gain per time unit scales with the internal binary angular momentum, so that most of the displacement is induced by stellar interactions occurring around the time of MBHB binding, while the subsequent angular momentum enhancement gets eventually quashed by the effect of dynamical friction. The effect of the background rotation on the MBHB evolution may be relevant for LISA sources, that are expected to form in significantly rotating stellar systems.

scholarly journals On the eccentricity evolution of massive black hole binaries in stellar backgrounds

2020 ◽  
Vol 493 (1) ◽  
pp. L114-L119 ◽  
Author(s):  
Matteo Bonetti ◽  
Alexander Rasskazov ◽  
Alberto Sesana ◽  
Massimo Dotti ◽  
Francesco Haardt ◽  
...  
Keyword(s):  
Black Hole ◽  
Angular Momentum ◽  
Dynamical Evolution ◽  
Massive Black Hole ◽  
Massive Black Holes ◽  
Black Hole Binaries ◽  
Simple Extrapolation ◽  
Sgr A ◽  
The Masses ◽  
Three Body

ABSTRACT We study the dynamical evolution of eccentric massive black hole binaries (MBHBs) interacting with unbound stars by means of an extensive set of three-body scattering experiments. Compared to previous studies, we extend the investigation down to a MBHB mass ratio of q = m2/m1 = 10−4, where m1 and m2 are the masses of the primary and secondary hole, respectively. Contrary to a simple extrapolation from higher mass ratios, we find that for q ≲ 10−3 the eccentricity growth rate becomes negative, i.e. the binary circularizes as it shrinks. This behaviour is due to the subset of interacting stars captured in metastable counter-rotating orbits; those stars tend to extract angular momentum from the binary, promoting eccentricity growth for q > 10−3, but tend to inject angular momentum into the binary driving it towards circularization for q < 10−3. The physical origin of this behaviour requires a detailed study of the orbits of this subset of stars and is currently under investigation. Our findings might have important consequences for intermediate massive black holes (IMBHs) inspiralling on to MBHs (e.g. a putative $10^3\,\rm M_{\odot }$ black hole inspiralling on to Sgr A*).

scholarly journals Formation of counter-rotating and highly eccentric massive black hole binaries in galaxy mergers

2021 ◽  
Vol 503 (1) ◽  
pp. 498-510
Author(s):  
Imran Tariq Nasim ◽  
Cristobal Petrovich ◽  
Adam Nasim ◽  
Fani Dosopoulou ◽  
Fabio Antonini
Keyword(s):  
Black Hole ◽  
Gravitational Wave ◽  
Dynamical Evolution ◽  
Orbital Plane ◽  
Equal Mass ◽  
Galaxy Mergers ◽  
High Eccentricity ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Binary Evolution

ABSTRACT Supermassive black hole (SMBH) binaries represent the main target for missions such as the Laser Interferometer Space Antenna and Pulsar Timing Arrays. The understanding of their dynamical evolution prior to coalescence is therefore crucial to improving detection strategies and for the astrophysical interpretation of the gravitational wave data. In this paper, we use high-resolution N-body simulations to model the merger of two equal-mass galaxies hosting a central SMBH. In our models, all binaries are initially prograde with respect to the galaxy sense of rotation. But, binaries that form with a high eccentricity, e ≳ 0.7, quickly reverse their sense of rotation and become almost perfectly retrograde at the moment of binary formation. The evolution of these binaries proceeds towards larger eccentricities, as expected for a binary hardening in a counter-rotating stellar distribution. Binaries that form with lower eccentricities remain prograde and at comparatively low eccentricities. We study the origin of the orbital flip by using an analytical model that describes the early stages of binary evolution. This model indicates that the orbital plane flip is due to the torque from the triaxial background mass distribution that naturally arises from the galactic merger process. Our results imply the existence of a population of SMBH binaries with a high eccentricity and could have significant implications for the detection of the gravitational wave signal emitted by these systems.

scholarly journals Formation of discs around super-massive black hole binaries

2014 ◽  
Vol 10 (S312) ◽  
pp. 48-51
Author(s):  
Felipe G. Goicovic ◽  
Jorge Cuadra ◽  
Alberto Sesana
Keyword(s):  
Black Hole ◽  
Molecular Clouds ◽  
Equal Mass ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Supermassive Black Hole ◽  
First Results

AbstractWe model numerically the evolution of 104M⊙ turbulent molecular clouds in near-radial infall onto 106M⊙, equal-mass supermassive black hole binaries, using a modified version of the SPH code gadget-3. We investigate the different gas structures formed depending on the relative inclination between the binary and the cloud orbits. Our first results indicate that an aligned orbit produces mini-discs around each black hole, almost aligned with the binary; a perpendicular orbit produces misaligned mini-discs; and a counter-aligned orbit produces a circumbinary, counter-rotating ring.

scholarly journals The LISA-Taiji Network: Precision Localization of Coalescing Massive Black Hole Binaries

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Wen-Hong Ruan ◽  
Chang Liu ◽  
Zong-Kuan Guo ◽  
Yue-Liang Wu ◽  
Rong-Gen Cai
Keyword(s):  
Black Hole ◽  
Equal Mass ◽  
Host Galaxy ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Electromagnetic Emissions ◽  
History Of ◽  
Individual Detector ◽  
The Universe

We explore a potential LISA-Taiji network to fast and accurately localize the coalescing massive black hole binaries. For an equal-mass binary located at redshift of 1 with a total intrinsic mass of 105M⊙, the LISA-Taiji network may achieve almost four orders of magnitude improvement on the source localization region compared to an individual detector. The precision measurement of sky location from the gravitational-wave signal may completely identify the host galaxy with low redshifts prior to the final black hole merger. Such identification of the host galaxy is vital for the follow-up variability in electromagnetic emissions of the circumbinary disc when the binary merges to a new black hole and enables the coalescing massive black hole binaries to be used as a standard siren to probe the expansion history of the Universe.

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 The TianQin project: Current progress on science and technology

2020 ◽  
Author(s):  
Jianwei Mei ◽  
Yan-Zheng Bai ◽  
Jiahui Bao ◽  
Enrico Barausse ◽  
Lin Cai ◽  
...  
Keyword(s):  
Black Hole ◽  
Ecliptic Plane ◽  
Mass Ratio ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Compact Binaries ◽  
Single Body ◽  
Science Operations ◽  
New Generation ◽  
Research Facilities

Abstract TianQin is a planned space-based gravitational wave (GW) observatory consisting of three Earth-orbiting satellites with an orbital radius of about $10^5 \, {\rm km}$. The satellites will form an equilateral triangle constellation the plane of which is nearly perpendicular to the ecliptic plane. TianQin aims to detect GWs between $10^{-4} \, {\rm Hz}$ and $1 \, {\rm Hz}$ that can be generated by a wide variety of important astrophysical and cosmological sources, including the inspiral of Galactic ultra-compact binaries, the inspiral of stellar-mass black hole binaries, extreme mass ratio inspirals, the merger of massive black hole binaries, and possibly the energetic processes in the very early universe and exotic sources such as cosmic strings. In order to start science operations around 2035, a roadmap called the 0123 plan is being used to bring the key technologies of TianQin to maturity, supported by the construction of a series of research facilities on the ground. Two major projects of the 0123 plan are being carried out. In this process, the team has created a new-generation $17 \, {\rm cm}$ single-body hollow corner-cube retro-reflector which was launched with the QueQiao satellite on 21 May 2018; a new laser-ranging station equipped with a $1.2 \, {\rm m}$ telescope has been constructed and the station has successfully ranged to all five retro-reflectors on the Moon; and the TianQin-1 experimental satellite was launched on 20 December 2019—the first-round result shows that the satellite has exceeded all of its mission requirements.

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