scholarly journals Bondi or not Bondi: the impact of resolution on accretion and drag force modelling for supermassive black holes

2018 ◽  
Vol 478 (1) ◽  
pp. 995-1016 ◽  
Author(s):  
R S Beckmann ◽  
A Slyz ◽  
J Devriendt
Keyword(s):  
Black Holes ◽  
Drag Force ◽  
Supermassive Black Holes ◽  
The Impact

scholarly journals Reflection spectra of thick accretion discs

2019 ◽  
Vol 491 (1) ◽  
pp. 417-426 ◽  
Author(s):  
Shafqat Riaz ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
Sourabh Nampalliwar
Keyword(s):  
Black Holes ◽  
Circular Orbit ◽  
Supermassive Black Holes ◽  
Accretion Disc ◽  
High Mass ◽  
Model Parameters ◽  
Reflection Spectra ◽  
Stable Circular Orbit ◽  
Innermost Stable Circular Orbit ◽  
The Impact

ABSTRACT Relativistic reflection features are commonly observed in the X-ray spectra of stellar-mass and supermassive black holes and originate from illumination of the inner part of the accretion disc by a hot corona. All the available relativistic reflection models assume that the disc is infinitesimally thin and the inner edge is at the innermost stable circular orbit or at a larger radius. However, we know that several sources, especially among supermassive black holes, have quite high-mass accretion rates. In such a case, the accretion disc becomes geometrically thick and the inner edge of the disc is expected to be inside the innermost stable circular orbit. In this work, we employ the Polish donut model to describe geometrically thick discs and we study the iron-line shapes from similar systems. We also simulate full reflection spectra and we analyse the simulated observations with a thin disc relativistic reflection model to determine the impact of the disc structure on the estimation of the model parameters, in particular in the case of tests of the Kerr hypothesis.

scholarly journals From galactic nuclei to the halo outskirts: tracing supermassive black holes across cosmic history and environments

2020 ◽  
Vol 495 (4) ◽  
pp. 4681-4706 ◽  
Author(s):  
David Izquierdo-Villalba ◽  
Silvia Bonoli ◽  
Massimo Dotti ◽  
Alberto Sesana ◽  
Yetli Rosas-Guevara ◽  
...  
Keyword(s):  
Black Holes ◽  
Cosmic Time ◽  
Mass Function ◽  
Supermassive Black Holes ◽  
Dominant Type ◽  
Central Regions ◽  
Mass Assembly ◽  
The One ◽  
Gas Accretion ◽  
The Impact

ABSTRACT We study the mass assembly and spin evolution of supermassive black holes (BHs) across cosmic time as well as the impact of gravitational recoil on the population of nuclear and wandering BHs (wBHs) by using the semi-analytical model L-Galaxies run on top of Millennium merger trees. We track spin changes that BHs experience during both coalescence events and gas accretion phases. For the latter, we assume that spin changes are coupled with the bulge assembly. This assumption leads to predictions for the median spin values of z = 0 BHs that depend on whether they are hosted by pseudo-bulges, classical bulges or ellipticals, being $\overline{a} \sim 0.9$, 0.7 and 0.4, respectively. The outcomes of the model display a good consistency with $z \le 4$ quasar luminosity functions and the $z = 0$ BH mass function, spin values, and BH correlation. Regarding the wBHs, we assume that they can originate from both the disruption of satellite galaxies (orphan wBH) and ejections due to gravitational recoils (ejected wBH). The model points to a number density of wBHs that increases with decreasing redshift, although this population is always $\rm {\sim}2\, dex$ smaller than the one of nuclear BHs. At all redshifts, wBHs are typically hosted in $\rm {\it M}_{halo} \gtrsim 10^{13} \, M_{\odot }$ and $\rm {\it M}_{stellar} \gtrsim 10^{10} \, M_{\odot }$, being orphan wBHs the dominant type. Besides, independently of redshift and halo mass, ejected wBHs inhabit the central regions (${\lesssim}\rm 0.3{\it R}_{200}$) of the host DM halo, while orphan wBH linger at larger scales (${\gtrsim}\rm 0.5{\it R}_{200}$). Finally, we find that gravitational recoils cause a progressive depletion of nuclear BHs with decreasing redshift and stellar mass. Moreover, ejection events lead to changes in the predicted local BH–bulge relation, in particular for BHs in pseudo-bulges, for which the relation is flattened at $\rm {\it M}_{bulge} \gt 10^{10.2}\, M_{\odot }$ and the scatter increase up to ${\sim}\rm 3\, dex$.

scholarly journals Gravitational wave driven mergers and coalescence time of supermassive black holes

2018 ◽  
Vol 615 ◽  
pp. A71 ◽  
Author(s):  
Fazeel Mahmood Khan ◽  
Peter Berczik ◽  
Andreas Just
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Supermassive Black Holes ◽  
Orbital Energy ◽  
Large Set ◽  
Galaxy Mergers ◽  
Graphic Processing Units ◽  
Semi Major Axis ◽  
Coalescence Time ◽  
The Impact

Aims. The evolution of supermassive black holes (SMBHs) initially embedded in the centres of merging galaxies realised with a stellar mass function (SMF) is studied from the onset of galaxy mergers until coalescence. Coalescence times of SMBH binaries are of great importance for black hole evolution and gravitational wave detection studies. Methods. We performed direct N-body simulations using the highly efficient and massively parallel phi-GRAPE+GPU code capable of running on high-performance computer clusters supported by graphic processing units (GPUs). Post-Newtonian terms up to order 3.5 are used to drive the SMBH binary evolution in the relativistic regime. We performed a large set of simulations with three different slopes of the central stellar cusp and different random seeds. The impact of a SMF on the hardening rate and the coalescence time is investigated. Results. We find that SMBH binaries coalesce well within one billion years when our models are scaled to galaxies with a steep cusp at low redshift. Here higher central densities provide a larger supply of stars to efficiently extract energy from the SMBH binary orbit and shrink it to the phase where gravitational wave (GW) emission becomes dominant, leading to the coalescence of the SMBHs. Mergers of models with shallow cusps that are representative of giant elliptical galaxies having central cores result in less efficient extraction of the binary’s orbital energy, due to the lower stellar densities in the centre. However, high values of eccentricity witnessed for SMBH binaries in such galaxy mergers ensure that the GW emission dominated phase sets in earlier at larger values of the semi-major axis. This helps to compensate for the less efficient energy extraction during the phase dominated by stellar encounters resulting in mergers of SMBHs in about 1 Gyr after the formation of the binary. Additionally, we witness mass segregation in the merger remnant resulting in enhanced SMBH binary hardening rates. We show that at least the final phase of the merger in cuspy low-mass galaxies would be observable with the GW detector eLISA.

scholarly journals Testing General Relativity with Supermassive Black Holes Using X-Ray Reflection Spectroscopy

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 2 ◽  
Author(s):  
Askar B. Abdikamalov ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi ◽  
Sourabh Nampalliwar ◽  
Ashutosh Tripathi ◽  
...  
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Strong Field ◽  
Supermassive Black Holes ◽  
Kerr Solution ◽  
Reflection Spectroscopy ◽  
Systematic Uncertainties ◽  
Preliminary Study ◽  
Spacetime Metric ◽  
The Impact

In this paper, we review our current efforts to test General Relativity in the strong field regime by studying the reflection spectrum of supermassive black holes. So far we have analyzed 11 sources with observations of NuSTAR, Suzaku, Swift, and XMM-Newton. Our results are consistent with General Relativity, according to which the spacetime metric around astrophysical black holes should be well approximated by the Kerr solution. We discuss the systematic uncertainties in our model and we present a preliminary study on the impact of some of them on the measurement of the spacetime metric.

scholarly journals Supermassive black holes in cosmological simulations I: MBH − M⋆ relation and black hole mass function

2021 ◽  
Author(s):  
Mélanie Habouzit ◽  
Yuan Li ◽  
Rachel S Somerville ◽  
Shy Genel ◽  
Annalisa Pillepich ◽  
...  
Keyword(s):  
Black Holes ◽  
Time Evolution ◽  
Galaxy Formation ◽  
Large Scale ◽  
Mass Function ◽  
Supermassive Black Holes ◽  
High Mass ◽  
Cosmological Simulations ◽  
Low Mass ◽  
The Impact

Abstract The past decade has seen significant progress in understanding galaxy formation and evolution using large-scale cosmological simulations. While these simulations produce galaxies in overall good agreement with observations, they employ different sub-grid models for galaxies and supermassive black holes (BHs). We investigate the impact of the sub-grid models on the BH mass properties of the Illustris, TNG100, TNG300, Horizon-AGN, EAGLE, and SIMBA simulations, focusing on the MBH − M⋆ relation and the BH mass function. All simulations predict tight MBH − M⋆ relations, and struggle to produce BHs of $M_{\rm BH}\leqslant 10^{7.5}\, \rm M_{\odot }$ in galaxies of $M_{\star }\sim 10^{10.5}-10^{11.5}\, \rm M_{\odot }$. While the time evolution of the mean MBH − M⋆ relation is mild ($\rm \Delta M_{\rm BH}\leqslant 1\, dex$ for 0 ≤ z ≤ 5) for all the simulations, its linearity (shape) and normalization varies from simulation to simulation. The strength of SN feedback has a large impact on the linearity and time evolution for $M_{\star }\leqslant 10^{10.5}\, \rm M_{\odot }$. We find that the low-mass end is a good discriminant of the simulation models, and highlights the need for new observational constraints. At the high-mass end, strong AGN feedback can suppress the time evolution of the relation normalization. Compared with observations of the local Universe, we find an excess of BHs with $M_{\rm BH}\geqslant 10^{9}\, \rm M_{\odot }$ in most of the simulations. The BH mass function is dominated by efficiently accreting BHs (log10 fEdd ≥ −2) at high redshifts, and transitions progressively from the high-mass to the low-mass end to be governed by inactive BHs. The transition time and the contribution of active BHs are different among the simulations, and can be used to evaluate models against observations.

scholarly journals The seeds of supermassive black holes and the role of local radiation and metal spreading

2019 ◽  
Vol 36 ◽  
Author(s):  
Umberto Maio ◽  
Stefano Borgani ◽  
Benedetta Ciardi ◽  
Margarita Petkova
Keyword(s):  
Black Holes ◽  
Background Radiation ◽  
Mass Function ◽  
Supermassive Black Holes ◽  
Initial Mass Function ◽  
Molecular Features ◽  
Stellar Radiation ◽  
Molecular Cooling ◽  
Hydrodynamical Simulations ◽  
The Impact

AbstractWe present cosmological hydrodynamical simulations including atomic and molecular non-equilibrium chemistry, multi-frequency radiative transfer (0.7–100 eV sampled over 150 frequency bins) and stellar population evolution to investigate the host candidates of the seeds of supermassive black holes coming from direct collapse of gas in primordial haloes direct-collapse black holes, DCBHs. We consistently address the role played by atomic and molecular cooling, stellar radiation and metal spreading of C, N, O, Ne, Mg, Si, S, Ca, Fe, etc. from primordial sources, as well as their implications for nearby quiescent proto-galaxies under different assumptions for early source emissivity, initial mass function, and metal yields. We find that putative DCBH (direct-collapse black holes) host candidates need powerful primordial stellar generations, since common solar-like stars and hot OB-type stars are neither able to determine the conditions for direct collapse nor capable of building up a dissociating Lyman–Werner background radiation field. Thermal and molecular features of the identified DCBH host candidates in the scenario with very massive primordial stars seem favourable, with illuminating Lyman–Werner intensities featuring values of 1 – 50J21. Nevertheless, additional nonlinear processes, such as merger events, substructure formation, rotational motions, and photo-evaporation, should inhibit pure direct-collapse black hole formation in two-third of the cases. Local turbulence may delay gas direct collapse almost irrespectively from other environmental conditions. The impact of large Lyman–Werner fluxes at distances smaller than ~5 kpc is severely limited by metal pollution.

scholarly journals Young stellar cluster dilution near supermassive black holes: the impact of vector resonant relaxation on neighbour separation

2020 ◽  
Vol 499 (2) ◽  
pp. 2714-2733
Author(s):  
Juan Giral Martínez ◽  
Jean-Baptiste Fouvry ◽  
Christophe Pichon
Keyword(s):  
Black Holes ◽  
Semimajor Axis ◽  
Orbital Plane ◽  
Angular Separation ◽  
Supermassive Black Holes ◽  
Characteristic Time Scale ◽  
Stellar Cluster ◽  
Orbital Parameters ◽  
Sgr A ◽  
The Impact

ABSTRACT We investigate the rate of orbital orientation dilution of young stellar clusters in the vicinity of supermassive black holes. Within the framework of vector resonant relaxation, we predict the time evolution of the two-point correlation function of the stellar orbital plane orientations as a function of their initial angular separation and diversity in orbital parameters (semimajor axis, eccentricity). As expected, the larger the spread in initial orientations and orbital parameters, the more efficient the dilution of a given set of co-eval stars, with a characteristic time-scale set up by the coherence time of the background potential fluctuations. A Markovian prescription that matches numerical simulations allows us to efficiently probe the underlying kinematic properties of the unresolved nucleus when requesting consistency with a given dilution efficiency, imposed by the observed stellar disc within the 1 arcsec of Sgr A*. As a proof of concept, we compute maps of constant dilution times as a function of the semimajor axis cusp index and fraction of intermediate-mass black holes in the old background stellar cluster. This computation suggests that vector resonant relaxation should prove useful in this context since it impacts orientations on time-scales comparable to the stars’ age.

scholarly journals Black Hole Feeding and Feedback in the Context of Galaxy Formation

2009 ◽  
Vol 5 (S267) ◽  
pp. 411-420
Author(s):  
Rachel S. Somerville
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
State Of The Art ◽  
Supermassive Black Holes ◽  
Cosmological Simulations ◽  
Evolution Of Galaxies ◽  
The Impact

AbstractI describe ways in which state-of-the-art cosmological simulations are modeling the growth and evolution of supermassive black holes (feeding), and the impact of the energy that they release on galaxies and their surroundings (feedback). I then discuss how this new picture of interconnected co-evolution of galaxies and black holes provides plausible explanations for several of the mysteries that have long vexed theorists studying galaxy formation within the hierarchical cold dark matter paradigm.

scholarly journals Nanofluid flow containing carbon nanotubes with quartic autocatalytic chemical reaction and Thompson and Troian slip at the boundary

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Muhammad Ramzan ◽  
Jae Dong Chung ◽  
Seifedine Kadry ◽  
Yu-Ming Chu ◽  
Muhammad Akhtar
Keyword(s):  
Mathematical Model ◽  
Carbon Nanotubes ◽  
Drag Force ◽  
Chemical Reaction ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Surface Drag ◽  
Nanofluid Flow ◽  
Velocity Parameter ◽  
The Impact

Abstract A mathematical model is envisioned to discourse the impact of Thompson and Troian slip boundary in the carbon nanotubes suspended nanofluid flow near a stagnation point along an expanding/contracting surface. The water is considered as a base fluid and both types of carbon nanotubes i.e., single-wall (SWCNTs) and multi-wall (MWCNTs) are considered. The flow is taken in a Dacry-Forchheimer porous media amalgamated with quartic autocatalysis chemical reaction. Additional impacts added to the novelty of the mathematical model are the heat generation/absorption and buoyancy effect. The dimensionless variables led the envisaged mathematical model to a physical problem. The numerical solution is then found by engaging MATLAB built-in bvp4c function for non-dimensional velocity, temperature, and homogeneous-heterogeneous reactions. The validation of the proposed mathematical model is ascertained by comparing it with a published article in limiting case. An excellent consensus is accomplished in this regard. The behavior of numerous dimensionless flow variables including solid volume fraction, inertia coefficient, velocity ratio parameter, porosity parameter, slip velocity parameter, magnetic parameter, Schmidt number, and strength of homogeneous/heterogeneous reaction parameters are portrayed via graphical illustrations. Computational iterations for surface drag force are tabulated to analyze the impacts at the stretched surface. It is witnessed that the slip velocity parameter enhances the fluid stream velocity and diminishes the surface drag force. Furthermore, the concentration of the nanofluid flow is augmented for higher estimates of quartic autocatalysis chemical.

scholarly journals Bootstrapped Newtonian Cosmology and the Cosmological Constant Problem

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 358
Author(s):  
Roberto Casadio ◽  
Andrea Giusti
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Physics ◽  
Gravitational Interaction ◽  
Newtonian Gravity ◽  
Cosmological Constant Problem ◽  
Newtonian Cosmology ◽  
Natural Solution ◽  
The Impact

Bootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces. We further discuss how such models of quantum cosmology can lead to a natural solution to the cosmological constant problem.

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