Large-scale Dynamics of Winds Originating from Black Hole Accretion Flows. II. Magnetohydrodynamics

Cui, Can; Yuan, Feng

doi:10.3847/1538-4357/ab6e6f

Cited by 20 publications

(16 citation statements)

References 76 publications

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“…Such field configurations obtained in this work are in excellent agreement with the global MHD simulations of a thin accretion disk with corona by Zhu & Stone (2018) and Mishra et al (2020). Powerful outflows are ubiquitously observed in accretion systems with different scales (e.g., Reeves et al 2009;Tombesi et al 2010Tombesi et al , 2013Tombesi et al , 2015Gofford et al 2015;Parker et al 2017;Reeves et al 2020), which may be one of the important feedback mechanisms influencing the host galaxies' dynamics, star formation, or even the growth of their central black holes (Springel et al 2005;McNamara & Nulsen 2007;Fabian 2012;Bu et al 2016;Beckmann et al 2017;Duan & Guo 2018;Li & Cao 2019b;Cui & Yuan 2020). Magnetic acceleration could be a main mechanism to driven these powerful outflows (Miller et al 2006;Fender et al 2004;Miller et al 2015;Fukumura et al 2015Fukumura et al , 2018Kraemer et al 2018;Miller et al 2020;.…”

Section: And Caosupporting

confidence: 79%

The large-scale magnetic field advected in the corona of a thin accretion disk

Li,

Cao

2021

Preprint

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Large-scale magnetic field is believed to play a key role in launching and collimating jets/outflows. It was found that advection of external field by a geometrically thin disk is rather inefficient, while the external weak field may be dragged inwards by fast radially moving tenuous or/and hot gas above the thin disk. We investigate the field advection in a thin (cold) accretion disk covered with hot corona, in which turbulence is responsible for the angular momentum transfer of the gas in the disk and corona. The radial velocity of the gas in the corona is significantly higher than that in the thin disk. Our calculations show that the external magnetic flux is efficiently transported inwards by the corona, and the field line is strongly inclined towards the disk surface, which help launching outflows. The field configurations are consistent with those observed in the numerical simulations. The strength of the field is substantially enhanced in the inner region of the disk (usually several orders of magnitude higher than the external field strength), which is able to drive a fraction of gas in the corona into outflows. This mechanism may be useful in explaining the observational features in X-ray binaries and active galactic nuclei. Our results may help understanding the physics of the magneto-hydrodynamic (MHD) simulations.

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Section: And Caosupporting

confidence: 79%

The large-scale magnetic field advected in the corona of a thin accretion disk

Li,

Cao

2021

Preprint

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“…Particularly, we signal the possibility of a magnetocentrifugal acceleration mechanism, which is capable to drive the wind up to very high terminal velocities. Typical values are ∼ 1 − 3 times the rotational velocity at the wind launching radius R 0 (Fukumura et al 2010(Fukumura et al , 2014Tombesi et al 2013;Cui & Yuan 2020). For R 0 = 50r G , this corresponds to terminal velocities between 0.14 and 0.42 c, thus easily accounting for the observed UFO velocities.…”

Section: Discussionmentioning

confidence: 92%

“…the z coordinate, with a velocity proportional to the disc rotational velocity v rot = 1 R 0 . The velocity along the φ coordinate is updated at each step to ensure the conservation of l. These initial conditions are rather general, and represents a good approximation of the radiatively-driven wind scenario (Proga et al 2000;Proga & Kallman 2004), as well as the magneto-hydrodynamic (MHD) scenario, in which the gas is lifted through magnetic field lines co-rotating with the disk (Blandford & Payne 1982;Contopoulos & Lovelace 1994;Fukumura et al 2010Fukumura et al , 2014Cui & Yuan 2020). [5.0, 15.8, 50.0, 158.1, 500.0]r G , an integration time of 10 6 t G , a logarithmic temporal resolution of 5 • 10 6 steps, as in Sect.…”

Section: Axisymmetric Wind Launched From An Accretion Diskmentioning

confidence: 99%

Speed limits for radiation driven SMBH winds

Luminari,

Nicastro,

Elvis

et al. 2020

Preprint

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Context. Ultra Fast Outflows (UFOs) have become an established feature in X-ray spectra of Active Galactic Nuclei (AGN). According to the standard picture, they are launched at accretion disc scales with relativistic velocities, up to 0.3-0.4 times the speed of light. Their high kinetic power is enough to induce an efficient feedback on galactic-scale, possibly contributing to the co-evolution between the central supermassive black hole (SMBH) and the host galaxy. It is therefore of paramount importance to fully understand the UFO physics, and in particular the forces driving their acceleration and the relation with the accretion flow from which they originate. Aims. In this paper, we investigate the impact of special relativity effects on the radiative pressure exerted onto the outflow. The radiation received by the wind decreases for increasing outflow velocity v, implying that the standard Eddington limit argument has to be corrected according to v. Due to the limited ability of the radiation to counteract the black hole gravitational attraction, we expect to find lower typical velocities with respect to the non-relativistic scenario. Methods. We integrate the relativistic-corrected outflow equation of motion for a realistic set of starting conditions. We concentrate on a range of ionisations, column densities and launching radii consistent with those typically estimated for UFOs. We explore a one-dimensional, spherical geometry and a three-dimensional setting with a rotating thin accretion disc. Results. We find that the inclusion of special relativity effects leads to sizeable differences in the wind dynamics and that v is reduced up to 50 % with respect to the non-relativistic treatment. We compare our results with a sample of UFO from the literature, and we find that the relativistic-corrected velocities are systematically lower than the reported ones, indicating the need for an additional mechanism, such as magnetic driving, to explain the highest velocity components. We note that these conclusions, derived for AGN winds, have a general applicability.

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“…In reality, the magnetic field is always be present and responsible for angular momentum transfer of the accretion disk. The properties of the winds in the presence of magnetic field should be different (Cui et al 2020b;Yang et al 2021a;Yang 2021b). In future, we plan to study the large-scale dynamics of winds driven by line force and Lorentz force.…”

Section: Discussionmentioning

confidence: 99%

“…In order to study the winds feedback, we have to know the properties of the winds at large scale. Cui et al (2020aCui et al ( , 2020b study the propagation of winds at large scale by analytical and simulation methods. They investigate winds both from hot accretion flows and cold thin disks.…”

Section: Introductionmentioning

confidence: 99%

Large-scale Dynamics of Winds Driven by Line Force from a Thin Accretion Disk

Zhu,

Bu,

Yang

et al. 2022

Preprint

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Winds play a significant role in active galactic nuclei feedback process. Previous simulations studying winds only focus on a small dynamical range. Therefore, it is unknown how far the winds can go and what the properties of the winds will be if they can move to large radii. We perform simulations to study the large scale dynamics of winds driven by line force. We find that the properties of the winds depend on both black hole mass (M BH ) and accretion disk luminosity. When the accretion disk luminosity is 0.6L edd (L edd being Eddington luminosity), independent of M BH , the winds have kinetic energy flux exceeding 1%L edd and can escape from the black hole potential. For the case with the accretion disk luminosity equaling 0.3L edd , the strength of the winds decreases with the decrease of M BH . If M BH decreases from 10 9 to 10 6 solar mass (M ), the winds kinetic energy flux decreases from ∼ 0.01L edd to ∼ 10 −6 L edd . In case of M BH 10 7 M , winds can escape from black hole potential. In the case of M BH = 10 6 M , the winds can not escape. We find that for the ultra-fast winds observed in hard X-ray bands (Gofford et al. 2015), the observed dependence of the mass flux and the kinetic energy flux on accretion disk luminosity can be well produced by line force driven winds model. We also find that the properties of the ultra-fast winds observed in soft X-ray bands can be explained by the line force driven winds model.

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Large-scale Dynamics of Winds Originating from Black Hole Accretion Flows. II. Magnetohydrodynamics

Cited by 20 publications

References 76 publications

The large-scale magnetic field advected in the corona of a thin accretion disk

The large-scale magnetic field advected in the corona of a thin accretion disk

Speed limits for radiation driven SMBH winds

Large-scale Dynamics of Winds Driven by Line Force from a Thin Accretion Disk

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