scholarly journals Hyper-Eddington accretion flows on to black holes accompanied by powerful outflows

2020 ◽  
Vol 497 (1) ◽  
pp. 302-317
Author(s):  
Eishun Takeo ◽  
Kohei Inayoshi ◽  
Shin Mineshige
Keyword(s):  
Black Holes ◽  
Surrounding Medium ◽  
Mechanical Power ◽  
Host Galaxy ◽  
Opening Angle ◽  
Radiative Feedback ◽  
Accretion Flows ◽  
Hydrodynamical Simulations ◽  
The Impact ◽  
Mechanical Feedback

ABSTRACT We perform two-dimensional radiation hydrodynamical simulations of accretion flows on to black holes (BHs) at the nuclei of protogalaxies, and study the impact of mechanical and radiative feedback on rapid growth of BHs. The outflows deposit mass, momentum, and energy into the surrounding medium and prevent mass accretion on to the BH, resulting in the reduction of radiative output. We find that when the BH is embedded in a dense gas core, ionizing radiation attenuated by inefficient BH feeding owing to mechanical feedback hardly affects the gas dynamics at the BH gravitational sphere of influence, from which intense inflows of neutral gas occur at rates substantially exceeding the Eddington limit without impeded by photoionization and heating. Since mechanical power of outflows driven by the rapidly accreting BH is sufficiently strong, bipolar outflows completely evacuate the surrounding gas in the polar region but mass inflows through the equatorial region maintain the BH accretion rate as high as $\sim 300\!-\!10^3~\dot{M}_{\rm Edd}$, which is reduced by one order of magnitude from those with radiative feedback alone. Furthermore, we find that the critical gas density required for rapid accretion is lower by a factor of ∼3, when mechanical feedback is considered. By studying the dependence on outflow parameters (e.g. opening angle, mass loading degree into outflows, velocity), we conclude that contrary to naive expectation, the stronger outflow leads to the transition to rapid accretion more efficiently. Rapidly growing BHs inject mechanical power with $\sim 0.1\!-\!1{{\ \rm per\ cent}}$ of the radiative luminosity into their host galaxy scales, which is used for cosmological simulations.

scholarly journals Winds and feedback from supermassive black holes accreting at low rates: hydrodynamical treatment

2020 ◽  
Vol 492 (2) ◽  
pp. 2553-2571 ◽  
Author(s):  
Ivan Almeida ◽  
Rodrigo Nemmen
Keyword(s):  
Black Holes ◽  
Initial Conditions ◽  
Rest Mass ◽  
Host Galaxy ◽  
Feedback Effects ◽  
Accretion Flows ◽  
Viscous Shear Stress ◽  
Viscous Shear ◽  
Thermally Driven ◽  
Hydrodynamical Simulations

ABSTRACT Outflows produced by a supermassive black hole (SMBH) can have important feedback effects in its host galaxy. An unresolved question is the nature and properties of winds from SMBHs accreting at low rates in low-luminosity active galactic nuclei (LLAGNs). We performed two-dimensional numerical, hydrodynamical simulations of radiatively inefficient accretion flows on to non-spinning black holes. We explored a diversity of initial conditions in terms of rotation curves and viscous shear stress prescriptions, and evolved our models for very long durations of up to 8 × 105GM/c3. Our models resulted in powerful subrelativistic, thermally driven winds originated from the corona of the accretion flow at distances 10−100 GM/c2 from the SMBH. The winds reached velocities of up to 0.01c with kinetic powers corresponding to $0.1\!-\!1 {\,{\rm per\, cent}}$ of the rest-mass energy associated with inflowing gas at large distances, in good agreement with models of the ‘radio mode’ of AGN feedback. The properties of our simulated outflows are in broad agreement with observations of winds in quiescent galaxies that host LLAGNs, which are capable of heating ambient gas and suppressing star formation.

scholarly journals Radiative Feedback Effects during Cosmic Reionization

2014 ◽  
Vol 11 (S308) ◽  
pp. 372-377
Author(s):  
David Sullivan ◽  
Ilian T. Iliev
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Early Universe ◽  
Galaxy Formation ◽  
Analytical Models ◽  
Feedback Effects ◽  
Radiative Feedback ◽  
Hydrodynamical Simulations ◽  
Matching Models ◽  
The Impact

AbstractWe present coupled radiation hydrodynamical simulations of the epoch of reionization, aimed at probing self-feedback on galactic scales. Unlike previous works, which assume a (quasi) homogeneous UV background, we self-consistently evolve both the radiation field and the gas to model the impact of previously unresolved processes such as spectral hardening and self-shielding. We find that the characteristic halo mass with a gas fraction half the cosmic mean, Mc(z), a quantity frequently used in semi-analytical models of galaxy formation, is significantly larger than previously assumed. While this results in an increased suppression of star formation in the early Universe, our results are consistent with the extrapolated stellar abundance matching models from Moster et al. 2013.

scholarly journals The impact of AGN wind feedback in simulations of isolated galaxies with a multiphase ISM

2020 ◽  
Vol 497 (4) ◽  
pp. 5292-5308 ◽  
Author(s):  
Paul Torrey ◽  
Philip F Hopkins ◽  
Claude-André Faucher-Giguère ◽  
Daniel Anglés-Alcázar ◽  
Eliot Quataert ◽  
...  
Keyword(s):  
Black Holes ◽  
High Redshift ◽  
Formation Rate ◽  
Feedback Mechanism ◽  
Host Galaxy ◽  
Merging Galaxies ◽  
Massive Black Holes ◽  
Stellar Feedback ◽  
Isolated Galaxies ◽  
The Impact

ABSTRACT Accreting black holes can drive fast and energetic nuclear winds that may be an important feedback mechanism associated with active galactic nuclei (AGN). In this paper, we implement a scheme for capturing feedback from these fast nuclear winds and examine their impact in simulations of isolated disc galaxies. Stellar feedback is modelled using the Feedback In Realistic Environments (fire) physics and produces a realistic multiphase interstellar medium (ISM). We find that AGN winds drive the formation of a low-density, high-temperature central gas cavity that is broadly consistent with analytic model expectations. The effects of AGN feedback on the host galaxy are a strong function of the wind kinetic power and momentum. Low- and moderate-luminosity AGN do not have a significant effect on their host galaxy: the AGN winds inefficiently couple to the ambient ISM and instead a significant fraction of their energy vents in the polar direction. For such massive black holes, accretion near the Eddington limit can have a dramatic impact on the host galaxy ISM: if AGN wind feedback acts for ≳20–30 Myr, the inner ∼1–10 kpc of the ISM is disrupted and the global galaxy star formation rate is significantly reduced. We quantify the properties of the resulting galaxy-scale outflows and find that the radial momentum in the outflow is boosted by a factor of ∼2–3 relative to that initially supplied in the AGN wind for strong feedback scenarios, decreasing below unity for less energetic winds. In contrast to observations, however, the outflows are primarily hot, with very little atomic or molecular gas. We conjecture that merging galaxies and high-redshift galaxies, which have more turbulent and thicker discs and very different nuclear gas geometries, may be even more disrupted by AGN winds than found in our simulations.

scholarly journals Mechanical feedback effects on primordial black hole accretion

2020 ◽  
Vol 638 ◽  
pp. A132 ◽  
Author(s):  
V. Bosch-Ramon ◽  
N. Bellomo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Accretion Rate ◽  
Compact Object ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Black Hole Accretion ◽  
The Impact ◽  
Hole Accretion ◽  
Mechanical Feedback

Context. Dark matter may consist, at least partially, of primordial black holes formed during the radiation-dominated era. The radiation produced by accretion onto primordial black holes leaves characteristic signatures on the properties of the medium at high redshift, before and after hydrogen recombination. Therefore, reliable modeling of accretion onto these objects is required to obtain robust constraints on their abundance. Aims. We investigate the effect of mechanical feedback, that is, the impact of outflows (winds and– or –jets) on the medium, on primordial black hole accretion, and thereby on the associated radiation. Methods. Using analytical and numerical calculations, we studied for the first time the possibility that outflows can reduce the accretion rate of primordial black holes with masses similar to those detected by the LIGO-Virgo collaboration. Results. Despite the complexity of the accretion rate evolution, mechanical feedback is useful in to significantly reducing the primordial black hole accretion rate, at least by one order of magnitude, when outflows are aligned with the motion of the compact object. If the outflow is perpendicular to the direction of motion, the effect is less important, but it is still non-negligible. Conclusions. Outflows from primordial black holes, even rather weak ones, can significantly decrease the accretion rate, effectively weakening abundance constraints on these objects. Our results motivate further numerical simulations with a more realistic setup, which would yield more precise quantitative predictions.

scholarly journals Impact of AGN feedback on galaxies and their multiphase ISM across cosmic time

2019 ◽  
Author(s):  
Milena Valentini ◽  
Giuseppe Murante ◽  
Stefano Borgani ◽  
Gian Luigi Granato ◽  
Pierluigi Monaco ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Cosmic Time ◽  
Host Galaxy ◽  
High Angular Momentum ◽  
Hot Gas ◽  
Resolution Model ◽  
Hydrodynamical Simulations ◽  
Gas Accretion ◽  
The Impact ◽  
Cold Gas

Abstract We present simulations of galaxy formation, based on the GADGET-3 code, in which a sub-resolution model for star formation and stellar feedback is interfaced with a new model for AGN feedback. Our sub-resolution model describes a multiphase ISM, accounting for hot and cold gas within the same resolution element: we exploit this feature to investigate the impact of coupling AGN feedback energy to the different phases of the ISM over cosmic time. Our fiducial model considers that AGN feedback energy coupling is driven by the covering factors of the hot and cold phases. We perform a suite of cosmological hydrodynamical simulations of disc galaxies (Mhalo, DM ≃ 2 · 1012 M⊙, at z = 0), to investigate: (i) the effect of different ways of coupling AGN feedback energy to the multiphase ISM; (ii) the impact of different prescriptions for gas accretion (i.e. only cold gas, both cold and hot gas, with the additional possibility of limiting gas accretion from cold gas with high angular momentum); (iii) how different models of gas accretion and coupling of AGN feedback energy affect the coevolution of supermassive BHs and their host galaxy. We find that at least a share of the AGN feedback energy has to couple with the diffuse gas, in order to avoid an excessive growth of the BH mass. When the BH only accretes cold gas, it experiences a growth that is faster than in the case in which both cold and hot gas are accreted. If the accretion of cold gas with high angular momentum is reduced, the BH mass growth is delayed, the BH mass at z = 0 is reduced by up to an order of magnitude, and the BH is prevented from accreting below z ≲ 2, when the galaxy disc forms.

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 AGN feedback and star formation in ETGs: negative and positive feedback

2015 ◽  
Vol 11 (S315) ◽  
pp. 224-227 ◽  
Author(s):  
Luca Ciotti ◽  
Jeremiah P. Ostriker ◽  
Andrea Negri ◽  
Silvia Pellegrini ◽  
Silvia Posacki ◽  
...  
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Stellar Population ◽  
State Of The Art ◽  
Host Galaxy ◽  
Early Type ◽  
Spatial And Temporal Scales ◽  
Cooling Flows ◽  
The Galaxy ◽  
Hydrodynamical Simulations

AbstractAGN feedback from supermassive black holes (SMBHs) at the center of early type galaxies is commonly invoked as the explanation for the quenching of star formation in these systems. The situation is complicated by the significant amount of mass injected in the galaxy by the evolving stellar population over cosmological times. In absence of feedback, this mass would lead to unobserved galactic cooling flows, and to SMBHs two orders of magnitude more massive than observed. By using high-resolution 2D hydrodynamical simulations with radiative transport and star formation in state-of-the-art galaxy models, we show how the intermittent AGN feedback is highly structured on spatial and temporal scales, and how its effects are not only negative (shutting down the recurrent cooling episodes of the ISM), but also positive, inducing star formation in the inner regions of the host galaxy.

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