Slow and massive: low-spin SMBHs can grow more

Zubovas, Kastytis; King, Andrew

doi:10.1093/mnras/stz2235

Cited by 11 publications

(9 citation statements)

References 69 publications

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“…As a consequence, slowlyrotating BHs should be more massive, as they can acquire larger masses due to weaker anisotropic feedback. This is somewhat similar to the conclusion that the slowest spinning BHs should be the most massive ones (Zubovas & King 2019), but with the addition of the angular dimension. This may also be qualitatively consistent with the observational trend suggesting that the more massive BHs tend to have lower BH spins (Reynolds 2019, and references therein).…”

Section: Connection To Accretionsupporting

confidence: 82%

“…In fact, low BH spins with correspondingly low radiative efficiencies, seem to be required in order to allow rapid BH growth, favouring some form of 'chaotic accretion' (King & Pringle 2006). Since low BH spins are less effective in generating powerful AGN feedback, it has been argued that low-spin BHs should be the most massive ones (Zubovas & King 2019).…”

Section: Connection To Accretionmentioning

confidence: 99%

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AGN anisotropic radiative feedback set by black hole spin

Ishibashi

2020

Preprint

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We consider the impact of anisotropic radiation on the active galactic nucleus (AGN) radiative dusty feedback. The radiation pattern originating from the accretion disc is determined by the central black hole (BH) spin. Here we analyse how such BH spin-induced angular dependence affects the dynamics and energetics of the radiation pressure-driven outflows, as well as AGN obscuration and BH accretion. In addition, we explore the effect of a spatially varying dust-to-gas ratio on the outflow propagation. We obtain two distinct trends for high-spin and low-spin objects, providing a direct connection between anisotropic feedback and BH spin. In the case of maximum spin, powerful quasi-spherical outflows can propagate on large scales, at all inclination angles with fairly uniform energetics. In contrast, in the case of zero spin, only weaker bipolar outflows can be driven in the polar directions. As a result, high BH spins can efficiently clear out the obscuring gas from most directions, whereas low BH spins can only remove dusty gas from the polar regions, hence also determining the overall AGN obscuration geometry. Due to such anisotropic feedback, high BH spins can prevent accretion of gas from most directions (except in the equatorial plane), while low BH spins allow inflows to proceed from a wider range of directions. This may have important implications for the BH growth in the early Universe. Anisotropic radiative dusty feedback, ruled by the BH spin, may thus play a major role in shaping AGN evolution over cosmic time.

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Section: Connection To Accretionsupporting

confidence: 82%

Section: Connection To Accretionmentioning

confidence: 99%

AGN anisotropic radiative feedback set by black hole spin

Ishibashi

2020

Preprint

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“…We speculate that reversing this assumption for thick disks may significantly reduce the spins of supermassive BHs in the most massive galaxies, as well as super-Eddington accretors. This may help models reproduce the observed population of billion solar mass quasars at z ∼ 6−7 (e.g., Shapiro 2005;Volonteri & Rees 2005;Zubovas & King 2019). In future work, we plan to explore the spin evolution of super-Eddington disks in more detail.…”

Section: Black Hole Spindown Over Cosmic Timementioning

confidence: 98%

Jets in Magnetically Arrested Hot Accretion Flows: Geometry, Power and Black Hole Spindown

Narayan,

Chael,

Chatterjee

et al. 2021

Preprint

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We present the results of nine simulations of radiatively-inefficient magnetically arrested disks (MADs) across different values of the black hole spin parameter a * : −0.9, −0.7, −0.5, −0.3, 0, 0.3, 0.5, 0.7, and 0.9. Each simulation was run up to t 100, 000 GM/c 3 to ensure disk inflow equilibrium out to large radii. We find that the saturated magnetic flux level, and consequently also jet power, of MAD disks depends strongly on the black hole spin, confirming the results of . Prograde disks saturate at a much higher relative magnetic flux and have more powerful jets than their retrograde counterparts. MADs with spinning black holes naturally launch jets with generalized parabolic profiles with width varying as a power of distance from the black hole. For distances up to 100GM/c 2 , the power-law index is k ≈ 0.27−0.42. There is a strong correlation between the disk-jet geometry and the dimensionless magnetic flux, resulting in prograde systems displaying thinner equatorial accretion flows near the black hole and wider jets, compared to retrograde systems. Prograde and retrograde MADs also exhibit different trends in disk variability: accretion rate variability increases with increasing spin for a * > 0 and remains almost constant for a * 0, while magnetic flux variability shows the opposite trend. Jets in the MAD state remove more angular momentum from black holes than is accreted, effectively spinning down the black hole. If powerful jets from MAD systems in Nature are persistent, this loss of angular momentum will notably reduce the black hole spin over cosmic time.

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“…Overmassive black holes are not fully understood but may arise from compact 'blue nugget' galaxies at high redshift (z ≥ 6), where high velocity dispersions allow SMBHs to reach larger masses (King & Nealon 2019). Slowspinning SMBHs are expected to be the most massive, as these are less efficient at producing feedback in the form of outflows (Zubovas & King 2019). The need for overmassive black holes in producing the largest observed cores is motivated by the approximately linear dependence of core sizes carved by both binary scouring (Merritt 2006) and GW recoil on SMBH mass (Gualandris & Merritt 2008).…”

Section: The Need For Overmassive Black Holesmentioning

confidence: 99%

Formation of the largest galactic cores through binary scouring and gravitational wave recoil

Nasim

Gualandris

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et al. 2021

Monthly Notices of the Royal Astronomical Society

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Massive elliptical galaxies are typically observed to have central cores in their projected radial light profiles. Such cores have long been thought to form through ‘binary scouring’ as supermassive black holes (SMBHs), brought in through mergers, form a hard binary and eject stars from the galactic centre. However, the most massive cores, like the ∼3 kpc core in A2261-BCG, remain challenging to explain in this way. In this paper, we run a suite of dry galaxy merger simulations to explore three different scenarios for central core formation in massive elliptical galaxies: ‘binary scouring’, ‘tidal deposition’ and ‘gravitational wave (GW) induced recoil’. Using the griffin code, we self-consistently model the stars, dark matter and SMBHs in our merging galaxies, following the SMBH dynamics through to the formation of a hard binary. We find that we can only explain the large surface brightness core of A2261-BCG with a combination of a major merger that produces a small ∼1 kpc core through binary scouring, followed by the subsequent GW recoil of its SMBH that acts to grow the core size. Key predictions of this scenario are an offset SMBH surrounded by a compact cluster of bound stars and a non-divergent central density profile. We show that the bright ‘knots’ observed in the core region of A2261-BCG are best explained as stalled perturbers resulting from minor mergers, though the brightest may also represent ejected SMBHs surrounded by a stellar cloak of bound stars.

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Slow and massive: low-spin SMBHs can grow more

Cited by 11 publications

References 69 publications

AGN anisotropic radiative feedback set by black hole spin

AGN anisotropic radiative feedback set by black hole spin

Jets in Magnetically Arrested Hot Accretion Flows: Geometry, Power and Black Hole Spindown

Formation of the largest galactic cores through binary scouring and gravitational wave recoil

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