Global Radiation Magnetohydrodynamic Simulations of sub-Eddington Accretion Disks around Supermassive Black Holes

Jiang, Yue-Qing; Blaes, Omer; Stone, James M.; Davis, Shane W.

doi:10.3847/1538-4357/ab4a00

Cited by 123 publications

(134 citation statements)

References 94 publications

Supporting

Mentioning

120

Contrasting

Order By: Relevance

“…Models of accretion discs provide some guidance on how discs adjust due to changes in accretion rates. Jiang et al (2019) ran two global radiation magnetohydrodynamics simulations of AGN discs separated by nearly a factor of 3 in accretion rate. They find that the surface density in the inner part of the disc rises with the accretion rate.…”

Section: Varying the Density And Thomson Depthmentioning

confidence: 99%

Sustaining a warm corona in active galactic nucleus accretion discs

Ballantyne

Xiang

2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Warm coronae, thick (τT = 10–20, where τT is the Thomson depth) Comptonizing regions with temperatures of ∼1 keV, are proposed to exist at the surfaces of accretion discs in active galactic nuclei (AGNs). By combining with the reflection spectrum, warm coronae may be responsible for producing the smooth soft excess seen in AGN X-ray spectra. This paper studies how a warm corona must adjust in order to sustain the soft excess through large changes in the AGN flux. Spectra from one-dimensional constant density and hydrostatic warm corona models are calculated assuming that the illuminating hard X-ray power law, gas density, Thomson depth, and coronal heating strength vary in response to changes in the accretion rate. We identify models that produce warm coronae with temperatures between 0.3 and 1.1 keV, and measure the photon indices and emitted fluxes in the 0.5–2 and 2–10 keV bands. Correlations and anticorrelations between these quantities depend on the evolution and structure of the warm corona. Tracing the path that an AGN follows through these correlations will constrain how warm coronae are heated and connected to the accretion disc. Variations in the density structure and coronal heating strength of warm coronae will lead to a variety of soft excess strengths and shapes in AGNs. A larger accretion rate will, on average, lead to a warm corona that produces a stronger soft excess, consistent with observations of local Seyfert galaxies.

show abstract

Section: Varying the Density And Thomson Depthmentioning

confidence: 99%

Sustaining a warm corona in active galactic nucleus accretion discs

Ballantyne

Xiang

2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…This heating function corresponds to a constant heating rate per particle over τ T . The hard X-ray power-law that irradiates the disc is assigned a total flux of f X D(R), following the expectation that the hot corona is heated by accretion energy transported outside of the disc (e.g., Jiang et al 2014Jiang et al , 2019b. In order to consider a large range of h f , we fix f X = 0.1, a value similar to the X-ray bolometric corrections inferred in local AGNs (e.g., Vasudevan & Fabian 2007;Netzer 2019).…”

Section: Calculationsmentioning

confidence: 99%

Examining the physical conditions of a warm corona in active galactic nuclei accretion discs

Ballantyne

2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

A warm corona at the surface of an accretion disc has been proposed as a potential location for producing the soft excess commonly observed in the X-ray spectra of active galactic nuclei (AGNs). In order to fit the observed data the gas must be at temperatures of ∼ 1 keV and have an optical depth of τ T ≈ 10-20. We present one-dimensional calculations of the physical conditions and emitted spectra of a τ T = 10 or 20 gas layer subject to illumination from an X-ray power-law (from above), a blackbody (from below) and a variable amount of internal heating. The models show that a warm corona with kT ∼ 1 keV can develop, producing a strong Comptonized soft excess, but only if the internal heating flux is within a relatively narrow range. Similarly, if the gas density of the layer is too large then efficient cooling will stop a warm corona from forming. The radiation from the hard X-ray power-law is crucial in producing a warm corona, indicating that a warm and hot corona may co-exist in AGN accretion discs, and their combined effect leads to the observed soft excess. Intense heating of a warm corona leads to steep X-ray spectra with ionised Fe Kα lines, similar to those seen in some narrow-line Seyfert 1 galaxies.An alternative model for the soft excess returns to the idea of direct emission from the AGN accretion disc, but now proposes

show abstract

“…The physical process of AGN feedback is rather complicated, but small-scale general-relativistic magnetohydrodynamic simulations have made remarkable progress in the past few years on both accretion disk physics and the launching of the jets/winds (Fragile et al 2007;Tchekhovskoy et al 2011;Bu et al 2016;Jiang et al 2019). Galactic-scale and cosmological-zoom simulations have also explored different ways of implementing AGN feedback, studied the effects of different feedback mechanisms, and improved our understanding of the complex interplay between galactic weather, star formation, and black hole activities (Omma et al 2004;Guo & Mathews 2011;Choi et al 2012;Li et al 2015;Yang & Reynolds 2016;Qiu et al 2019;Yuan et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Correlations between Black Holes and Host Galaxies in the Illustris and IllustrisTNG Simulations

Habouzit

Genel

et al. 2020

ApJ

View full text Add to dashboard Cite

We study black hole-host galaxy correlations, and the relation between the overmassiveness (the distance from the average M BH -σ relation) of supermassive black holes (SMBHs) and the star formation histories of their host galaxies in the Illustris and TNG100 simulations. We find that both simulations are able to produce black hole scaling relations in general agreement with observations at z=0, but with noticeable discrepancies. Both simulations show an offset from the observations for the M BH -σ relation, and the relation between M BH and the Sérsic index. The relation between M BH and stellar mass M * is tighter than the observations, especially for TNG100. For massive galaxies in both simulations, the hosts of overmassive SMBHs (those above the mean M BH -σ relation) tend to have larger Sérsic indices and lower baryon conversion efficiency, suggesting a multidimensional link between SMBHs and the properties of their hosts. In Illustris, the hosts of overmassive SMBHs have formed earlier and have lower present-day star formation rates, in qualitative agreement with the observations for massive galaxies with σ>100 km s −1 . For low-mass galaxies, such a correlation still holds in Illustris but does not exist in the observed data. For TNG100, the correlation between SMBH overmassiveness and star formation history is much weaker. The hosts of overmassive SMBHs generally have consistently larger star formation rates throughout history. These galaxies have higher stellar mass as well, due to the strong M BH -M * correlation. Our findings show that simulated SMBH scaling relations and correlations are sensitive to features in the modeling of SMBHs.Unified Astronomy Thesaurus concepts: Supermassive black holes (1663); Galaxies (573); Star formation (1569); Galaxy evolution (594)

show abstract

Global Radiation Magnetohydrodynamic Simulations of sub-Eddington Accretion Disks around Supermassive Black Holes

Cited by 123 publications

References 94 publications

Sustaining a warm corona in active galactic nucleus accretion discs

Sustaining a warm corona in active galactic nucleus accretion discs

Examining the physical conditions of a warm corona in active galactic nuclei accretion discs

Correlations between Black Holes and Host Galaxies in the Illustris and IllustrisTNG Simulations

Contact Info

Product

Resources

About