scholarly journals THE ACCRETION GEOMETRY IN RADIO-LOUD ACTIVE GALAXIES

2007 ◽  
Vol 22 (32) ◽  
pp. 2397-2411 ◽  
Author(s):  
D. R. BALLANTYNE
Keyword(s):  
Black Hole ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Host Galaxy ◽  
Jet Formation ◽  
Accretion Flow ◽  
Radio Jets ◽  
R Ratio ◽  
Accretion Rates ◽  
Field Geometry

We review the latest attempts to determine the accretion geometry in radio-loud active galactic nuclei (AGN). These objects, which comprise ~ 10–20% of the AGN population, produce powerful collimated radio jets that can extend thousands of parsecs from the center of the host galaxy. Recent multiwavelength surveys have shown that radio-loudness is more common in low-luminosity AGN than in higher luminosity Seyfert galaxies or quasars. These low-luminosity AGN have small enough accretion rates that they are most likely accreting via a geometrically thick and radiatively inefficient accretion flow. In contrast, X-ray spectroscopic observations of three higher luminosity broad-line radio galaxies (3C 120, 4C+74.26 and PG 1425+267) have found evidence for an untruncated thin disk extending very close to the black hole. These tentative detections indicate that, for this class of radio-loud AGN, the accretion geometry is very similar to their radio-quiet counterparts. These observations suggest that there are three conditions to jet formation that must be satisfied: the presence of a rapidly spinning black hole, an accretion flow with a large H/r ratio, and a favorable magnetic field geometry.

scholarly journals Radiative efficiency of hot accretion flow and the radio/X-ray correlation in X-ray binaries

2014 ◽  
Vol 10 (S312) ◽  
pp. 139-140
Author(s):  
Fu-Guo Xie
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Rate ◽  
Galactic Nuclei ◽  
X Ray ◽  
Radiative Efficiency ◽  
Accretion Flow ◽  
Accretion Rates ◽  
Distinctive Property ◽  
X Ray Binaries

AbstractSignificant progresses have been made since the discovery of hot accretion flow, a theory successfully applied to the low-luminosity active galactic nuclei (LLAGNs) and black hole (BH) X-ray binaries (BHBs) in their hard states. Motivated by these updates, we re-investigate the radiative efficiency of hot accretion flow. We find that, the brightest regime of hot accretion flow shows a distinctive property, i.e. it has a constant efficiency independent of accretion rates, similar to the standard thin disk. For less bright regime, the efficiency has a steep positive correlation with the accretion rate, while for faint regime typical of advection-dominated accretion flow, the correlation is shadower. This result can naturally explain the observed two distinctive correlations between radio and X-ray luminosities in black hole X-ray binaries. The key difference in systems with distinctive correlations could be the viscous parameter, which determines the critical luminosity of different accretion modes.

scholarly journals Numerical Simulation of Relativistic Jet Formation in Black Hole Magnetosphere

1998 ◽  
Vol 188 ◽  
pp. 415-416 ◽  
Author(s):  
Shinji Koide ◽  
Kazunari Shibata ◽  
Takahiro Kudoh
Keyword(s):  
Black Hole ◽  
Galactic Nuclei ◽  
Apparent Velocity ◽  
Jet Formation ◽  
Radio Jets ◽  
Relativistic Jet ◽  
Superluminal Motion ◽  
Protostellar Jets ◽  
General Relativistic ◽  
Magnetic Mechanism

The radio jets ejected from active galactic nuclei (AGNs) sometimes show proper motions with apparent velocity exceeding the speed of light. This phenomenon, called superluminal motion, is explained as relativistic jets propagating in a direction almost toward us, and has been thought to be ejected from the close vicinity of hypothetical supermassive black holes powering AGNs (Rees 1996). The magnetic mechanism has been proposed not only for AGN jets (Lovelace 1976; Blandford & Payne 1983) but also for protostellar jets (Pudritz & Norman 1986; Uchida & Shibata 1985; Shibata & Uchida 1986), although no one has yet performed nonsteady general relativistic magnetohydrodynamic (GRMHD) numerical simulations on the formation of jets from the accretion disk around a black hole.

scholarly journals General relativistic radiation transport: Implications for VLBI/EHT observations of AGN discs, winds and jets

2021 ◽  
Author(s):  
Bidisha Bandyopadhyay ◽  
Christian Fendt ◽  
Dominik R G Schleicher ◽  
Christos Vourellis
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Ray Tracing ◽  
Radiation Transport ◽  
Galactic Nuclei ◽  
Black Hole Mass ◽  
Jet Formation ◽  
Post Process ◽  
Accretion Rates ◽  
General Relativistic

Abstract In 2019, the Event Horizon Telescope Collaboration (EHTC) has published the first image of a supermassive black hole (SMBH) obtained via the Very Large Baseline Interferometry (VLBI) technique. In the future, it is expected that additional and more sensitive VLBI observations will be pursued for other nearby Active Galactic Nuclei (AGN), and it is therefore important to understand which possible features can be expected in such images. In this paper, we post-process General Relativistic Magneto-Hydrodynamical (GR-MHD) simulations which include resistivity, thus providing a self-consistent jet formation model, including resistive mass loading of a wind launched from a disc in Keplerian rotation. The ray-tracing is done using the General Relativistic Ray-Tracing code GRTRANS assuming synchrotron emission. We study the appearance of the black hole environment including the accretion disc, winds and jets under a large range of condition, varying black hole mass, accretion rate, spin, inclination angle, disc parameters and observed frequency. When we adopt M87-like parameters, we show that we can reproduce a ring-like feature (similar as observed by the EHT) for some of our simulations. The latter suggests that such Keplerian disc models thus could be consistent with the observed results. Depending on their masses, accretion rates, spin and the sensitivity of the observation, we note that other SMBHs may show additional features like winds and jets in the observations.

scholarly journals The Lx–Luv–Lradio relation and corona–disc–jet connection in optically selected radio-loud quasars

2020 ◽  
Vol 496 (1) ◽  
pp. 245-268 ◽  
Author(s):  
S F Zhu (朱世甫) ◽  
W N Brandt ◽  
B Luo (罗斌) ◽  
Jianfeng Wu (武剑锋) ◽  
Y Q Xue (薛永泉) ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Small Scale ◽  
Spectral Slope ◽  
Physical Processes ◽  
X Ray ◽  
Accretion Flow ◽  
Radio Jets ◽  
Spectrum Radio ◽  
Uniform Sample

ABSTRACT Radio-loud quasars (RLQs) are more X-ray luminous than predicted by the X-ray–optical/UV relation (i.e. $L_\mathrm{x}\propto L_\mathrm{uv}^\gamma$) for radio-quiet quasars (RQQs). The excess X-ray emission depends on the radio-loudness parameter (R) and radio spectral slope (αr). We construct a uniform sample of 729 optically selected RLQs with high fractions of X-ray detections and αr measurements. We find that steep-spectrum radio quasars (SSRQs; αr ≤ −0.5) follow a quantitatively similar $L_\mathrm{x}\propto L_\mathrm{uv}^{\gamma }$ relation as that for RQQs, suggesting a common coronal origin for the X-ray emission of both SSRQs and RQQs. However, the corresponding intercept of SSRQs is larger than that for RQQs and increases with R, suggesting a connection between the radio jets and the configuration of the accretion flow. Flat-spectrum radio quasars (FSRQs; αr > −0.5) are generally more X-ray luminous than SSRQs at given Luv and R, likely involving more physical processes. The emergent picture is different from that commonly assumed where the excess X-ray emission of RLQs is attributed to the jets. We thus perform model selection to compare critically these different interpretations, which prefers the coronal scenario with a corona–jet connection. A distinct jet component is likely important for only a small portion of FSRQs. The corona–jet, disc–corona, and disc–jet connections of RLQs are likely driven by independent physical processes. Furthermore, the corona–jet connection implies that small-scale processes in the vicinity of supermassive black holes, probably associated with the magnetic flux/topology instead of black hole spin, are controlling the radio-loudness of quasars.

scholarly journals General Relativistic Simulation of Jet Formation from Magnetized Accretion Disk

1997 ◽  
Vol 163 ◽  
pp. 667-671
Author(s):  
Shinji Koide ◽  
Kazunari Shibata ◽  
Takahiro Kudoh
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Galactic Nuclei ◽  
Lorentz Factor ◽  
Numerical Code ◽  
Jet Formation ◽  
Relativistic Jet ◽  
Relativistic Regime ◽  
General Relativistic

AbstractRecently, superluminal motions are observed not only from active galactic nuclei but also in our Galaxy. These phenomena are explained as relativistic jets propagating almost toward us with Lorentz factor more than 2. For the formation of such a relativistic jet, magnetically driven mechanism around a black hole is most promising. We have extended the 2.5D Newtonian MHD jet model (Shibata & Uchida 1986) to general relativistic regime. For this purpose, we have developed a general relativistic magnetohydrodynamic (GRMHD) numerical code and applied it to the simulation of the magnetized accretion disk around a black hole. We have found the formation of magnetically driven jets with 86 percent of light velocity (i.e. Lorentz factor ~ 2.0).

scholarly journals Evidence for jet driven outflows: the case of 3C293

2014 ◽  
Vol 10 (S313) ◽  
pp. 289-293
Author(s):  
E. K. Mahony ◽  
J. B. R. Oonk ◽  
R. Morganti ◽  
T. A. Oosterloo ◽  
B. H. C. Emonts ◽  
...  
Keyword(s):  
Black Hole ◽  
Galaxy Evolution ◽  
Direct Evidence ◽  
Host Galaxy ◽  
Central Black Hole ◽  
Radio Jets ◽  
Neutral Gas ◽  
The Galaxy ◽  
Mass Outflow ◽  
Gas Quenching

AbstractThe tight correlations observed between galaxies and their SMBH provides compelling evidence that the evolution of the galaxy and its central black hole are strongly linked. This is generally attributed to feedback mechanisms which, according to simulations, often take the form of outflows of gas, quenching star formation in the host galaxy and halting accretion onto the central black hole. While there are a number of plausible ways that outflows could be produced, recent results have shown that in some cases radio jets could be responsible for driving fast outflows of gas. One such example is seen in the nearby radio galaxy 3C293. In this talk I will present results from JVLA radio observations where we detect fast outflows (~1200 km/s) of neutral gas which are being driven by the radio-jet approximately 0.5 kpc from the central core, providing direct evidence for jet-ISM interaction. This is accompanied with recent IFU observations showing that ionised gas outflows are also being driven by the radio jet. Pinpointing the location of these outflows enables us to derive crucial parameters, such as the mass outflow rates and kinetic energy involved, which we can compare to predictions from galaxy evolution simulations.

scholarly journals MEASURING SUPERMASSIVE BLACK HOLE SPINS IN AGN

2013 ◽  
Vol 53 (A) ◽  
pp. 652-658 ◽  
Author(s):  
Laura Brenneman
Keyword(s):  
Black Hole ◽  
Current Knowledge ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Relative Role ◽  
Large Area ◽  
Gas Accretion ◽  
Area X ◽  
Spin Measurements

Measuring the spins of supermassive black holes (SMBHs) in active galactic nuclei (AGN) can inform us about the relative role of gas accretion vs. mergers in recent epochs of the life of the host galaxy and its AGN. Recent theoretical and observation advances have enabled spin measurements for ten SMBHs thus far, but this science is still very much in its infancy. Herein, I discuss how we measure black hole spin in AGN, using recent results from a long Suzaku campaign on NGC 3783 to illustrate this process and its caveats. I then present our current knowledge of the distribution of SMBH spins in the local universe. I also address prospects for improving the accuracy, precision and quantity of these spin constraints in the next decade and beyond with instruments such as NuSTAR, Astro-H and future large-area X-ray telescopes.

scholarly journals On Spin dependence of the Fundamental Plane of black hole activity

2020 ◽  
Vol 495 (1) ◽  
pp. 278-284 ◽  
Author(s):  
Caner Ünal ◽  
Abraham Loeb
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Rate ◽  
Galactic Nuclei ◽  
Spin Dependence ◽  
Fundamental Plane ◽  
X Ray ◽  
Dependent Relation ◽  
Accretion Rates ◽  
Jet Power

ABSTRACT The Fundamental Plane (FP) of black hole (BH) activity in galactic nuclei relates X-ray and radio luminosities to BH mass and accretion rate. However, there is a large scatter exhibited by the data, which motivated us for a new variable. We add BH spin as a new variable and estimate the spin dependence of the jet power and disc luminosity in terms of radio and X-ray luminosities. We assume the Blandford–Znajek process as the main source of the outflow, and find that the jet power depends on BH spin stronger than quadratically at moderate and large spin values. We perform a statistical analysis for 10 active galactic nuclei (AGNs) which have sub-Eddington accretion rates and whose spin values are measured independently via the reflection or continuum-fitting methods, and find that the spin-dependent relation describes the data significantly better. This analysis, if supported with more data, could imply not only the spin dependence of the FP relation, but also the Blandford–Znajek process in AGN jets.

scholarly journals The starburst – active galactic nuclei connection on nuclear scales in near by Seyfert galaxies

2013 ◽  
Vol 9 (S304) ◽  
pp. 345-346
Author(s):  
Pilar Esquej
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
High Angular Resolution ◽  
Physical Relation ◽  
Black Hole Accretion ◽  
Star Formation Activity ◽  
Hole Accretion

AbstractSeveral works have shown that there is an empirical correlation between the star formation rate and the luminosity of the active galactic nucleus (and thus the black hole accretion rate, ṀBH) of Seyfert galaxies. This suggests a physical relation between the gas forming stars on kpc scales and the gas on sub-pc scales that is feeding the black hole. Simulations predict this relation and also that the correlation should be more prominent on smaller physical scales. We have compiled high angular resolution (0.4–0.8″) mid-infrared spectroscopy obtained with T-ReCS, VISIR, and Michelle of 29 Seyferts. We use the 11.3 μm PAH feature to probe the star formation activity in the inner ~65 pc, and its relation with the ṀBH on these physical scales.

scholarly journals Black Hole Demographics: Statistical Characteristics of Accreting Black Holes

2009 ◽  
Vol 5 (S267) ◽  
pp. 213-222
Author(s):  
Hagai Netzer
Keyword(s):  
Growth Rate ◽  
Black Holes ◽  
Black Hole ◽  
High Redshift ◽  
Parallel Evolution ◽  
Statistical Characteristics ◽  
Small Samples ◽  
Host Galaxy ◽  
Data Sets ◽  
Accretion Rates

This review summarizes the important properties of active black holes (BHs) up to z ~ 2; their mass, accretion rate, and growth rate. At higher redshifts, such information is only available for small samples that do not represent the entire population of active galactic nuclei (AGNs). Black hole spin is still unknown; it is speculated to change with redshift, but with little experimental evidence. The available data sets also enable a direct comparison of BH accretion rates and host galaxy star-formation rates (SFRs). The ratio of the BH growth rate g(BH) and the bulge growth rate g(bulge), suggests that the two are proportional to each other. The local value of g(bulge)/g(BH) in low-luminosity AGNs is of order 100 and the corresponding ratio in high-luminosity, high-redshift AGNs is of order 10. This has important implications regarding the parallel evolution of active BHs and their hosts.

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