A universal critical accretion rate for black hole jet formation
International Centre for Radio Astronomy Research, Curtin University(国际射电天文研究中心,科廷大学);School of Natural Sciences, Institute for Advanced Study(自然科学与院,高等研究院)
Adelle J. Goodwin, Andrew Mummery
备注:
8 pages + 48 pages of appendices. 3 Figures + 19 Figures in appendices. Under review, comments welcome. Both authors contributed equally
It has long been suspected that black hole accretion-outflow coupling is invariant from the stellar to supermassive scales. Stellar mass black hole accretion flows are known to launch jets and outflows as they transition through critical accretion rate thresholds, with values well constrained observationally owing to their short evolutionary timescales. In contrast, accretion flows in typical supermassive black hole (SMBH) systems (those in active galactic nuclei) evolve over thousands of years, making the critical transitions at which jets are launched impossible to constrain in individual systems. Tidal disruption events (TDEs) provide the unique opportunity to witness the birth and evolution of an accretion flow onto a SMBH which evolves on timescales of years. Here we show that TDEs launch outflows during a super-Eddington accretion phase and a second, physically distinct outflow, at a critical accretion rate of $L_{\rm crit} \approx0.02$ $L_{\rm Edd}$, the same as the critical accretion rate for state transitions observed in accreting stellar mass black holes. This work naturally explains the mechanism, observed properties, and detection rate for prompt and delayed outflows observed in TDEs, which until now have been open problems. More broadly, we demonstrate that SMBHs exhibit the same accretion-outflow coupling as stellar mass black holes and that the critical low accretion rate threshold for jet formation in black holes is scale invariant.
Astrophysical jets are launched from strongly magnetized systems that host an accretion disk surrounding a central object. Here we address the question how to generate the accretion disk magnetization and field structure required for jet launching. We continue our work from Paper I (Mattia & Fendt 2020a), considering a non-scalar accretion disk mean-field $α^2Ω$-dynamo in the context of large scale disk-jet simulations. We now investigate a disk dynamo that follows analytical solutions of mean-field dynamo theory, essentially based only on a single parameter, the Coriolis number. We thereby co…
Astrophysical jets are launched from strongly magnetized systems that host an accretion disk surrounding a central object. The origin of the jet launching magnetic field is one of the open questions for modeling the accretion-ejection process. Here we address the question how to generate the accretion disk magnetization and field structure required for jet launching. Applying the PLUTO code, we present the first resistive MHD simulations of jet launching including a non-scalar accretion disk mean-field $α^2Ω$-dynamo in the context of large scale disk-jet simulations. Essentially, we find the $…
We explore the formation, energetics, and geometry of relativistic jets along with the variability of their central engine. We study both fast and slowly rotating black holes and address our simulations to active galaxy (AGN) centers and gamma ray burst (GRB) engines. The structured jets are postulated to account for emission properties of high energy sources across the mass scale, launched from stellar mass black holes in GRBs and from supermassive black holes in AGNs. Their active cores contain magnetized accretion disks and rotation of the Kerr black hole provides a mechanism for jet launch…
GRRMHD Simulations of Tidal Disruption Event Accretion Disks around Supermassive Black Holes: Jet Formation, Spectra, and Detectability
利用广义相对论辐射MHD(GRRMHD)模拟了由潮汐扰动事件(TDE)形成的超爱丁顿黑洞(BH)吸积盘。我们考虑基准的情况下,太阳质量的恒星在一个温和的穿透轨道被一个超大质量BH的质量$10^6 \, M_\odot$破坏,并考虑峰值回落率的时代。我们对模拟数据进行后处理以计算视角相关光谱。我们进行了一个参数的研究作为BH自旋和磁通量的函数的吸积盘的动力学,并计算模型光谱作为观察者的视角的函数。我们还考虑基于模型光谱的检测限。我们发现,一个吸积盘与一个相对较弱的磁场周围的BH(所谓的SANE制度的吸积)不发射相对论性喷流,无论BH是旋转。这种模式合理地再现了非喷流TDE的几个观测特性。对于具有强磁场(MAD区域)的非旋转BH也是如此。我们的一个模拟有一个快速旋转的BH(自旋参数0.9)以及一个MAD吸积盘。这个模型发射了一个强大的相对论性喷流,它是由BH自旋能量驱动的。它令人惊讶地再现了喷射的TDE Swift J1644+57的高能量发射和喷射结构。因此,喷射TDE可能对应于具有快速旋转BH和MAD吸积的TDE系统的子集。
We perform three general-relativistic magnetohydrodynamic simulations of black hole accretion designed to test how sensitive results are to grid resolution in the jet region. The cases differ only in numerics, modelling the same physical scenario of a radiatively inefficient, geometrically thick, magnetically arrested flow onto a rapidly spinning black hole. Properties inferred with the coarsest grid generally agree with those found with higher resolutions, including total jet power and its decomposition into different forms, velocity structure, nonaxisymmetric structure, and the appearance of…
Based on previously published multi-wavelength modelling of the GRB 170817A jet afterglow, that includes information from the VLBI centroid motion, we construct the posterior probability density distribution on the total energy in the bipolar jets launched by the GW170817 merger remnant. By applying a new numerical-relativity-informed fitting formula for the accretion disk mass, we construct the posterior probability density distribution of the GW170817 remnant disk mass. By combining the two, we estimate the accretion-to-jet energy conversion efficiency in this system, carefully accounting fo…
Magnetic fields lines are trapped in black hole event horizons by accreting plasma. If the trapped field lines are lightly loaded with plasma, then their motion is controlled by their footpoints on the horizon and thus by the spin of the black hole. In this paper, we investigate the boundary layer between lightly loaded polar field lines and a dense, equatorial accretion flow. We present an analytic model for aligned prograde and retrograde accretion systems and argue that there is significant shear across this "jet-disk boundary" at most radii for all black hole spins. Specializing to retrogr…
There is a very popular two-zone accretion disk model that the inner part of the non-advective Keplerian disk (Shakura-Sunyaev disk) can produce hot advection-dominated accretion flow, which can generate high energy power-law radiation and outflows/jets. However, we find that this simple model is inadequate to automatically explain many properties of the sources (such as hysteresis effect, counter-clockwise traversal in a hardness-intensity diagram, peculiar variabilities, and association/non-association of jets in a black hole $X-$ray binary) without considering additional assumptions. We als…
We study ejection mechanisms for two kinds of steady jets: one observed from black hole binaries in the low/hard state and the other from SS433. The specific energy of the ejected gas is required to be positive for the jets to get to infinity, while that of the accreted gas is naively considered to be negative at the outermost boundary of the accretion flow. To reconcile the opposite sign of the specific energies, we propose a situation where two layers exist in the accretion flow and one layer receives energy from the other sufficiently for the specific energy to be positive. For the steady j…
On the relation of accretion rate and spin induced jet power in low luminosity AGN
根据Liu and Han(2014),吸积主导的喷流功率与吸积速率成线性比例,而在较低吸积速率下,幂律指数<=0.5。将低吸积率活动星系核中的喷流功率归因于黑洞的自旋,意味着喷流功率比吸积主导的喷流功率随吸积率变化的谱更平坦。黑洞必须快速旋转才能有效地产生这样的喷流能量,这可能使我们能够在射电噪声大的低光度活动星系核中找到高自旋黑洞。
Jet Power, Bulk Lorentz Factor, Black Hole Spin, and Magnetic Field of Accretion Disk in Jetted Active Galactic Nuclei: A Large Gamma-Ray Emission Sample
Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences(中国科学院天体结构与演化重点实验室);Center for Astrophysics, Guangzhou University(广州大学天体物理中心);Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province(广东省教育厅天文学科学与技术研究实验室);Center for Astronomy and Astrophysics and Department of Physics, Fudan University(复旦大学天文与天体物理中心及物理系);Department of Astronomy, University of Science and Technology of China(中国科学技术大学天文系);School of Astronomy and Space Science, University of Science and Technology of China(中国科学技术大学天文与空间科学学院);Shanghai Astronomical Obs(上海天文台)
We investigate the dependence of the GRB jet structure and its evolution on the properties of the accreting torus in the central engine. Our models numerically evolve the accretion disk around a Kerr black hole using 3D general relativistic magnetohydrodynamic simulations. We use two different analytical hydrodynamical models of the accretion disk, based on the Fishbone-Moncrief and Chakrabarti solutions, as our initial states for the structure of the collapsar disk and the remnant after a binary neutron star merger, respectively. We impose poloidal magnetic fields of two different geometries …
Theoretical models show that the power of relativistic jets of active galactic nuclei depends on the spin and mass of the central supermassive black holes, as well as the accretion. Here we report an analysis of archival observations of a sample of blazars. We find a significant correlation between jet kinetic power and the spin of supermassive black holes. At the same time, we use multiple linear regression to analyze the relationship between jet kinetic power and accretion, spin and black hole mass. We find that the spin of supermassive black holes and accretion are the most important contri…
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…
The models that seek to explain the reflection spectrum in black hole binaries usually invoke a point-like primary source of hard X-rays. This source illuminates the accretion disk and gives rise to the discrete (lines) and continuum-reflected components. The main goal of this work is to investigate whether the extended, mildly relativistic jet that is present in black hole binaries in the hard and hard-intermediate states is the hard X-ray source that illuminates the accretion disk. We use a Monte Carlo code that simulates the process of inverse Compton scattering in a mildly relativistic jet…
Episodic ejections of blobs (episodic jets) are widely observed in black hole sources and usually associated with flares. In this paper, by performing and analyzing three dimensional general relativity magnetohydrodynamical numerical simulations of accretion flows, we investigate their physical mechanisms. We find that magnetic reconnection occurs in the accretion flow, likely due to the turbulent motion and differential rotation of the accretion flow, resulting in flares and formation of flux ropes. Flux ropes formed inside of 10-15 gravitational radii are found to mainly stay within the accr…