We study slowly rotating accretion flow at parsec and sub-parsec scale irradiated by a low luminosity active galactic nuclei. We take into account the Compton heating, photoionization heating by the central X-rays. The bremsstrahlung cooling, recombination and line cooling are also included. We find that due to the Compton heating, wind can be thermally driven. The power of wind is in the range $(10^{-6}-10^{-3}) L_{\rm Edd}$, with $L_{\rm Edd}$ being the Eddington luminosity. The mass flux of wind is in the range $(0.01-1) \dot M_{\rm Edd}$ ($\dot M_{\rm Edd}= L_{\rm Edd}/0.1c^2$ is the Eddington accretion rate, $c$ is speed of light). We define the wind generation efficiency as $ε= P_W/\dot {M}_{\rm BH}c^2$, with $P_W$ being wind power, $\dot M_{\rm BH}$ being the mass accretion rate onto the black hole. $ε$ lies in the rage $10^{-4}-1.18$. Wind production efficiency decreases with increasing mass accretion rate. The possible role of the thermally driven wind in the active galactic feedback is briefly discussed.
Super-massive black holes (SMBHs) spend most of their lifetime accreting at a rate well below the Eddington limit, manifesting themselves as low-luminosity active galactic nuclei (LLAGNs). The prevalence of a hot wind from LLAGNs is a generic prediction by theories and numerical simulations of black hole accretion and is recently becoming a crucial ingredient of AGN kinetic feedback in cosmological simulations of galaxy evolution. However, direct observational evidence for this hot wind is still scarce. In this work, we identify significant Fe XXVI Ly$α$ and Fe XXV K$α$ emission lines from hig…
For most of their lifetime, super-massive black holes (SMBHs) commonly found in galactic nuclei obtain mass from the ambient at a rate well below the Eddington limit, which is mediated by a radiatively inefficient, hot accretion flow. Both theory and numerical simulations predict that a strong wind must exist in such hot accretion flows. The wind is of special interest not only because it is an indispensable ingredient of accretion, but perhaps more importantly, it is believed to play a crucial role in the evolution of the host galaxy via the so-called kinetic mode AGN feedback. Observational …
Previous works show strong winds exist in hot accretion flows around black holes. Those works focus only on the region close to the black hole thus it is unknown whether or where the wind production stops at large radii. In this paper, we investigate this problem by hydrodynamical simulations. We take into account gravities of both the black hole and the nuclear star clusters. For the latter, we assume that the velocity dispersion of stars is a constant and its gravitational potential $\propto σ^2 \ln (r)$, where $σ$ is the velocity dispersion of stars and $r$ is the distance from the center o…
We perform two-dimensional simulations to study how the wind strength changes with accretion rate. We take into account bremsstrahlung, synchrotron radiation and the Comptonization. We find that when the accretion rate is low, radiative cooling is not important, the accretion flow is hot accretion flow. For the hot accretion flow, wind is very strong. The mass flux of wind can be $\sim 50\%$ of the mass inflow rate. When the accretion rate increases to a value at which radiative cooling rate is roughly equal to or slightly larger than viscous heating rate, cold clumps can form around the equat…
Previous works have clearly shown the existence of winds from black hole hot accretion flow and investigated their detailed properties. In extremely low accretion rate systems, the collisional mean-free path of electrons is large compared with the length-scale of the system, thus thermal conduction is dynamically important. When the magnetic field is present, the thermal conduction is anisotropic and energy transport is along magnetic field lines. In this paper, we study the effects of anisotropic thermal conduction on the wind production in hot accretion flows by performing two-dimensional ma…
We solve the two-dimensional hydrodynamic equations of hot accretion flow in the presence of the thermal conduction. The flow is assumed to be in steady-state and axisymmetric, and self-similar approximation is adopted in the radial direction. In this hydrodynamic study, we consider the viscous stress tensor to mimic the effects of the magnetorotational instability for driving angular momentum. We impose the physical boundary conditions at both the rotation axis and the equatorial plane and obtain the solutions in the full $ r-θ$ space. We have found that thermal conduction is indispensable te…
Numerical simulations of black hole hot accretion flows have shown the existence of strong wind. Those works focus only on the region close to black hole thus it is unknown whether or where the wind production stops at large radii. To address this question, Bu et al. (2016) have performed hydrodynamic (HD) simulations by taking into account the gravitational potential of both the black hole and the nuclear star clusters. The latter is assumed to be $\propto σ^2 \ln(r)$, with $σ$ being the velocity dispersion of stars and $r$ be the distance from the center of the galaxy. It was found that when…
This is the fourth paper of our series of works studying winds from hot accretion flows around black holes. In the first two papers, we have shown the existence of strong winds in hot accretion flows using hydrodynamical and magnetohydrodynamical (MHD) simulations. In the third paper, by using three dimensional general relativity MHD numerical simulation data of hot accretion flows and adopting a "virtual particle trajectory" data analysis approach, we have calculated the properties of wind, such as its mass flux and velocity. However, that paper focuses only on a non-spinning black hole and S…
Observations indicate that wind can be generated in hot accretion flow. By performing numerical simulations, Yuan et al. studied the detailed properties of wind generated from weakly magnetized accretion flow. However, properties of wind generated from strongly magnetized hot accretion flow have not been studied. In this paper, we study the properties of wind generated from both weakly and strongly magnetized accretion flow. We focus on how the magnetic field strength affects the wind properties. We solve time-steady two-dimensional magnetohydrodynamic (MHD) equations of black hole accretion i…
Previous numerical simulations have shown that strong winds can be produced in the hot accretion flows around black holes. Most of those studies focus only on the region close to the central black hole, therefore it is unclear whether the wind production stops at large radii around Bondi radius. Bu et al. 2016 studied the hot accretion flow around the Bondi radius in the presence of nuclear star gravity. They find that when the nuclear stars gravity is important/comparable to the black hole gravity, winds can not be produced around the Bondi radius. However, for some galaxies, the nuclear star…
我们研究混合热非热同步辐射光谱从球对称，光学薄风，考虑到相对论效应。在相对论性流场中，由于相对论性聚束效应，观测到的光谱往往向高频、高强度方向移动。然而，在光学薄的流出，我们发现，所观察到的光谱的强度相比，发射的，虽然峰值频率向高频方向移动。这是因为在光学薄流出中，我们可以看到远离观察者的远侧流。因此，我们仔细考虑光学薄的相对论性流围绕黑洞，如Sgr A $^*$。
We study the effects of accretion environment (gas density, temperature and angular momentum) at large radii ($\sim 10$pc) on luminosity of hot accretion flows. The radiative feedback effects from the accretion flow on the accretion environment are also self-consistently taken into account. We find that the slowly rotating flows at large radii can significantly deviate from Bondi accretion when radiation heating and cooling are considered. We further find that when the temperature of environment gas is low (e.g. $T=2\times 10^7$K), the luminosity of hot accretion flows is high. When the temper…
Hydrodynamical simulation of wind production from hot accretion flows in tidal disruption events
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Shanghai Key Lab for Astrophysics, Shanghai Normal University（上海师范大学天体物理上海市重点实验室）；Department of Physics, Chongqing University（重庆大学物理学院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
The mechanisms that drive disk winds are a window into the physical processes that underlie the disk. Stellar-mass black holes are an ideal setting in which to explore these mechanisms, in part because their outbursts span a broad range in mass accretion rate. We performed a spectral analysis of the disk wind found in six Chandra/HETG observations of the black hole candidate 4U~1630$-$472, covering a range of luminosities over two distinct spectral states. We modeled both wind absorption and extended wind re-emission components using PION, a self-consistent photoionized absorption model. In al…
A disk wind can cause perturbations that propagate throughout the disk via diffusive processes. On reaching the inner disk, these perturbations can change the disk luminosity, which in turn, can change the wind mass loss rate, $\dot{M}_w$. It has been argued that this so-called "wind driven relaxation cycle" might explain the observed variability in some disk accreting objects. Here, we study the response of the innermost mass accretion rate $\dot{M}_a$ to the loss of matter at different rates and radii. We allow the wind launching radius, $R_L$, to scale with $\dot{M}_a$. We computed a grid o…
We fit a new line shape model to \textit{Chandra} X-ray spectra of the O supergiant $ζ$ Puppis to test the robustness of mass-loss rates derived from X-ray wind line profiles against different assumed heating models. Our goal is to track the hot gas by replacing the common assumption that it is proportional to the cool gas emission measure. Instead of assuming a turn-on radius for the hot gas (as appropriate for the line-deshadowing instability internal to the wind), we parametrize the hot gas in terms of a mean-free path for accelerated low-density gas to encounter slower high-density materia…
