Black Holes In AGN Research Articles

RELATIVISTIC MASS OF SPINNING BLACK HOLES IN AGN

Aims: To calculate the relativistic mass of spinning black holes in AGN on the basis of model formulated with the help of the model for estimation of mass of black holes M=rv2/G [1,2] and the model for variation of Universal constant (G) with spinning velocity of black holes in the strong gravitational field as proposed by Mahto et al. [3].
 Study Design: The data for the mass of spinning black holes in AGN in ranging from 106 to 109.5 solar masses [2] and spinning velocity from 50 to 100% of velocity of light [4] and radius of event horizon corresponding to the masses from 1.475x109m to 1.475x1012m [5] have been used to calculate the required results. This work is a supplement part of the research paper entitled: Relativistic Mass of Spinning Black Holes in XRBs published in Research Square (preprint, 2023) and communicated to Astrophysics and Space Science (2022).
 Place and Duration of Study: Department of Physics, Marwari College under TMBU Bhagalpur from January 2021 to September 2023 and Bhagalpur College of Engineering, Bhagalpur under DST, Govt. of Bihar, India from October, 2023 to January 2023.
 Methodology: The present work is completely theoretical based on specific model and data analysis. The work is completed at the residence of author as well as personal chamber of the working institution.
 Results: The work gives the calculation for the relativistic mass of spinning black holes in the case of AGN to give the confirmation of the validity of special relativity.
 Conclusion: The present work gives the validity in support of theory of relativity in AGN as well as proposed model and can be frequently used for the estimation of the relativistic mass of AGN SBHs.

A general relativistic mass-to-distance ratio for a set of megamaser AGN black holes

ABSTRACT In this work, we perform a Bayesian statistical fit to estimate the mass-to-distance ratio and the recessional redshift of 10 different black holes hosted at the centre of active galactic nuclei, namely the galaxies NGC 5765b, NGC 6323, UGC 3789, CGCG 074−064, ESO 558−G009, NGC 2960, NGC 6264, NGC 4388, J0437+2456, and NGC 2273. Our general relativistic method makes use of the positions in the sky and frequency shift observations of water megamasers circularly orbiting the central black hole on their accretion discs. This approach also allows us to quantify the gravitational redshift that is not considered in a Newtonian analysis. The gravitational redshift of the megamasers closest to the black hole is found to be within the range 1–6 km s−1. The order of the fitted black hole masses corresponds to supermassive black holes and lies on the range 106−107M⊙.

Positron Annihilation Spectroscopy of Active Galactic Nuclei

This paper focuses on the interpretation of radiation fluxes from active galactic nuclei. The advantage of positron annihilation spectroscopy over other methods of spectral diagnostics of active galactic nuclei (therefore AGN) is demonstrated. A relationship between regular and random components in both bolometric and spectral composition of fluxes of quanta and particles generated in AGN is found. We consider their diffuse component separately and also detect radiative feedback after the passage of high-velocity cosmic rays and hard quanta through gas-and-dust aggregates surrounding massive black holes in AGN. The motion of relativistic positrons and electrons in such complex systems produces secondary radiation throughout the whole investigated region of active galactic nuclei in form of cylinder with radius R= 400-1000 pc and height H=200-400 pc, thus causing their visible luminescence across all spectral bands. We obtain radiation and electron energy distribution functions depending on the spatial distribution of the investigated bulk of matter in AGN. Radiation luminescence of the noncentral part of AGN is a response to the effects of particles and quanta falling from its center created by atoms, molecules and dust of its diffuse component. The cross-sections for the single-photon annihilation of positrons of different energies with atoms in these active galactic nuclei are determined. For the first time we use the data on the change in chemical composition due to spallation reactions induced by high-energy particles. We establish or define more accurately how the energies of the incident positron, emitted γ-quantum and recoiling nucleus correlate with the atomic number and weight of the target nucleus. For light elements, we provide detailed tables of all indicated parameters. A new criterion is proposed, based on the use of the ratio of the fluxes of γ-quanta formed in one- and two-photon annihilation of positrons in a diffuse medium. It is concluded that, as is the case in young supernova remnants, the two-photon annihilation tends to occur in solid-state grains as a result of active loss of kinetic energy of positrons due to ionisation down to thermal energy of free electrons. The singlephoton annihilation of positrons manifests itself in the gas component of active galactic nuclei. Such annihilation occurs as interaction between positrons and K-shell electrons; hence, it is suitable for identification of the chemical state of substances comprising the gas component of the investigated media. Specific physical media producing high fluxes of positrons are discussed; it allowed a significant reduction in the number of reaction channels generating positrons. We estimate the brightness distribution in the γ-ray spectra of the gas-and-dust media through which positron fluxes travel with the energy range similar to that recorded by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) research module. Based on the results of our calculations, we analyse the reasons for such a high power of positrons to penetrate through gas-and-dust aggregates. The energy loss of positrons by ionisation is compared to the production of secondary positrons by high-energy cosmic rays in order to determine the depth of their penetration into gas-and-dust aggregations clustered in active galactic nuclei. The relationship between the energy of γ-quanta emitted upon the single-photon annihilation and the energy of incident electrons is established. The obtained cross sections for positron interactions with bound electrons of the diffuse component of the non-central, peripheral AGN regions allowed us to obtain new spectroscopic characteristics of the atoms involved in singlephoton annihilation.

Status of spinning black holes in AGN

Status of spinning black holes in AGN

Change in Entropy of Spinning Black Holes Due to Corresponding Change in Mass in AGN

The present paper discusses the change in entropy of spinning black holes due to change in mass for AGN black holes on the basis of the model as proposed in the case of XRBs under condition that the black holes spin with unit spinning parameter and angular momentum and this model gives slightly some different nature of the super-massive spinning black holes in AGN as specified for XRBs.

On the mean radiative efficiency of accreting massive black holes in AGNs and QSOs

Radiative efficiency is an important physical parameter that describes the fraction of accretion material converted to radiative energy for accretion onto massive black holes (MBHs). With the simplest Sołtan argument, the radiative efficiency of MBHs can be estimated by matching the mass density of MBHs in the local universe to the accreted mass density by MBHs during AGN/QSO phases. In this paper, we estimate the local MBH mass density through a combination of various determinations of the correlations between the masses of MBHs and the properties of MBH host galaxies, with the distribution functions of those galaxy properties. We also estimate the total energy density radiated by AGNs and QSOs by using various AGN/QSO X-ray luminosity functions in the literature. We then obtain several hundred estimates of the mean radiative efficiency of AGNs/QSOs. Under the assumption that those estimates are independent of each other and free of systematic effects, we apply the median statistics as described by Gott et al. and find the mean radiative efficiency of AGNs/QSOs is ϵ = 0.105 −0.008 +0.006 , which is consistent with the canonical value ~0.1. Considering that about 20% Compton-thick objects may be missed from current available X-ray surveys, the true mean radiative efficiency may be actually ~0.12.

Studying the outskirts of reverberation mapped AGNs

AbstractAbout 100 AGNs have their black hole mass measured directly using the reverberation mapping technique over the past few decades. By now we have high enough numbers to explore unique subsamples within these objects and to study phenomena across variety of AGNs. I will review recent reverberation mapping studies which focus on high-redshift high-luminosity AGNs and on AGNs with super-Eddington accreting massive black holes. These studies enable to investigate the BLR size, mass, and luminosity relations in different subsamples of AGNs and to check whether there are differences in these relations in different types of AGNs. In particular I will discuss the following questions: Is the BLR size - luminosity relation the same over the whole AGNs luminosity range? Are there different relations for different types of AGNs? What are these studies teaching us about theory of accretion into black holes in AGNs?

Accretion disks around binary black holes of unequal mass: General relativistic MHD simulations of postdecoupling and merger

We report results from simulations in general relativity of magnetized disks accreting onto merging black hole binaries, starting from relaxed disk initial data. The simulations feature an effective, rapid radiative cooling scheme as a limiting case of future treatments with radiative transfer. Here we evolve the systems after binary-disk decoupling through inspiral and merger, and analyze the dependence on the binary mass ratio with $q\equiv m_{\rm bh}/M_{\rm BH}=1,1/2,$ and $1/4$. We find that the luminosity associated with local cooling is larger than the luminosity associated with matter kinetic outflows, while the electromagnetic (Poynting) luminosity associated with bulk transport of magnetic field energy is the smallest. The cooling luminosity around merger is only marginally smaller than that of a single, non-spinning black hole. Incipient jets are launched independently of the mass ratio, while the same initial disk accreting on a single non-spinning black hole does not lead to a jet, as expected. For all mass ratios we see a transient behavior in the collimated, magnetized outflows lasting $2-5 ( M/10^8M_\odot ) \rm days$ after merger: the outflows become increasingly magnetically dominated and accelerated to higher velocities, boosting the Poynting luminosity. These sudden changes can alter the electromagnetic emission across the jet and potentially help distinguish mergers of black holes in AGNs from single accreting black holes based on jet morphology alone.

Observational Appearance of Black Holes in X-Ray Binaries and AGN

Accretion onto black holes powers most luminous compact sources in the Universe. Black holes are found with masses extending over an extraordinary broad dynamic range, from several to a few billion times the mass of the Sun. Depending on their position on the mass scale, they may manifest themselves as X-ray binaries or active galactic nuclei. X-ray binaries harbor stellar mass black holes—endpoints of the evolution of massive stars. They have been studied by X-ray astronomy since its inception in the early 60-ies, however, the enigma of the most luminous of them—ultra-luminous X-ray sources, still remains unsolved. Supermassive black holes, lurking at the centers of galaxies, are up to hundreds of millions times more massive and give rise to the wide variety of different phenomena collectively termed “Active Galactic Nuclei”. The most luminous of them reach the Eddington luminosity limit for a few billions solar masses object and are found at redshifts as high as z≥5–7. Accretion onto supermassive black holes in AGN and stellar- and (possibly) intermediate mass black holes in X-ray binaries and ultra-luminous X-ray sources in star-forming galaxies can explain most, if not all, of the observed brightness of the cosmic X-ray background radiation. Despite the vast difference in the mass scale, accretion in X-ray binaries and AGN is governed by the same physical laws, so a degree of quantitative analogy among them is expected. Indeed, all luminous black holes are successfully described by the standard Shakura-Sunyaev theory of accretion disks, while the output of low-luminosity accreting black holes in the form of mechanical and radiative power of the associated jets obeys to a unified scaling relation, termed as the “fundamental plane of black holes”. From that standpoint, in this review we discuss formation of radiation in X-ray binaries and AGN, emphasizing their main similarities and differences, and examine our current knowledge of the demographics of stellar mass and supermassive black holes.

A transition mass for black holes to show broad emission lines

Although the super-massive (AGN) and stellar mass (XRBs) black holes have many properties in common, the broad emission lines (BELs) are exclusively signatures of the AGN. Based on the detection of these lines from SDSS data bases, there seems to be no AGN with mass M_BH \lesssim 10^5 M_sun. In this paper we investigate if such low mass black holes are really non-existent or they are undetected because the BELs in them are not produced efficiently. Using the ionizing spectral energy distribution for a wide range of black hole mass, 10 - 10^9 M_sun, spanning XRBs to AGN, we calculate the equivalent widths (EWs) of ultraviolet and optical lines Ly\alpha 1216 \AA, H\beta 4861 \AA, CIV 1549 \AA and MgII 2798 \AA. The LOC (locally optimally emitting cloud) model has been used to describe the broad emission line region (BELR) for the calculations. We find that the hardening of the SED shape with decreasing mass do not decrease the BEL EWs. However, finite size of the BELR, as measured by the line widths, which is controlled by the mass of the black hole, regulates the production of these emission lines. There seems to be a peak in the EWs of the emission lines for typical AGN black holes of ~ 10^8 M_sun, below which the lines become intrinsically fainter with a sharp fall-off below ~ 10^6 M_sun. This may be the cause of the absence of low mass AGN in SDSS.

BROAD IRON LINES IN NEUTRONS STARS: DYNAMICAL BROADENING OR WIND SCATTERING?

Broad iron emission lines are observed in many accreting systems from black holes in AGN and X-ray binaries to neutron star low-mass X-ray binaries. The origin of the line broadening is often interpreted as due to dynamical broadening and relativistic effects. However, alternative interpretations have been proposed, included broadening due to Compton scattering in a wind or accretion disk atmosphere. Here we explore the observational signatures expected from broadening in a wind, in particular that the iron line width should increase with an increase in the column density of the absorber (due to an increase in the number of scatterings). We study the data from three neutron star low-mass X-ray binaries where both a broad iron emission line and absorption lines are seen simultaneously, and show that there is no significant correlation between line width and column density. This favors an inner disk origin for the line broadening rather than scattering in a wind.

Radiative Efficiency of Black Holes in AGN

Neeraj Pant et al.(2010) gave a detailed study of BCT First solution (Tewari,1988) representing time dependent balls of perfect fluid with matter-radiation in general relativity to assume the life time of quasar 107 years, initial mass≈108M with an initial linear dimension≈1015 cm are radiating energy at a constant rate i.e. L∞=1047 ergs/sec with the gravitational red shift, z=0.44637. For quasars with LQSO~1046erg/sec, the black hole masses in those systems must be at least 108 solar masses (Astro 3830: Spring 2004). In the present work, we have calculated the radiative efficiency of black holes existing in AGN by using the formula L/Mc2 (Narayan2005, Xie & Yuan 2012) and compared our results regarding some characteristics of super massive black holes with some other works given in references like Astro 3830:Spring (2004), Narayan (2005), Xie & Yuan (2012) and Chan (2013) and concluded that the mass of black holes never be greater than 5×109 M⊙ as well as the radiative efficiency of black hole is smaller than the same mass of quasars.

SwiftPublication Statistics and the Comparison with Other Major Observatories

The gamma-ray bursts (GRB) Swift satellite was launched at the end of 2004 and is funded until 2014. Its γ -ray, X-ray, and optical-UV instruments discover and localize about 100 GRBs per year. We report on the success of this mission by counting the number of papers with Swift data and their impact ( i.e. , number of citations to those papers) for the publication years 2005 to 2011. In the first year, the number of papers was 24, and it steadily increased to 287 in the year 2011, reaching Keck. If this trend continues, before the end of the mission Swift may be approaching XMM-Newton and Chandra, with ~400 publications. Science topics of Swift publications have widened over time, and in 2011 almost 3/4 of all publications were about other energetic targets, such as AGN, novae, supernovae, X-ray binaries, pulsars, massive and stellar black holes.

Accurate AGN Black Hole Masses and the Scatter in the MBH–Lbulge Relationship

AbstractA new empirical formulae is given for estimating the masses of black holes in AGNs from the Hβ velocity dispersion and the continuum luminosity at 5100 Å. It is calibrated to reverberation-mapping and stellar-dynamical estimates of black hole masses. The resulting mass estimates are as accurate as reverberation-mapping and stellar-dynamical estimates. The new mass estimates show that there is very little scatter in the MBH–Lbulge relationship for high-luminosity galaxies, and that the scatter increases substantially in lower-mass galaxies.

Optical and X-ray variability of Seyfert galaxies NGC 5548, NGC 7469, NGC 3227, NGC 4051, NGC 4151, Mrk 509, Mrk 79, and Akn 564 and quasar 1E 0754

The results of a cross-correlation analysis of the optical and X-ray light curves for eight Seyfert galaxies, NGC 5548, NGC 7469, NGC 3227, NGC 4051, NGC 4151, Mrk 509, Mrk 79, and Akn 564 and for the optical spectra of the quasar 1E 0754 are presented. In the case of the galaxies NGC 5548 and NGC 7469, the maximum values of cross-correlation coefficients for optical and X-ray variations proved to be high (0.73 and 0.79, respectively). The lag time, determined from the maximum of cross-correlation function, is 2.800 −1.58 +3.12 days for NGC 5548 and 0.6 −4.3 +0.9 days for NGC 7469. This result favors downscattering of the X-ray emission into the optical range (direct Compton effect) for NGC 5548 and NGC 7469. In addition to the main maximum, which corresponds to the lag of the optical flux variations behind the X-ray flux, six objects (excluding Akn 564 and NGC 4151) show the wings in the intervals of cross-correlation functions that correspond to the time lags of X-ray emission behind the optical emission of approximately 10 days. A method of determining the masses of central black holes in AGNs through spectral line widths is presented; with this method the mass of the central black hole in the quasar 1E 0754 was found (M BH = 1.01 × 108 M sun). The position of the quasar 1E 0754 in the mass-luminosity diagram meets the position of other NLS 1 galaxies.

SELF-CONSISTENT MODELS OF THE AGN AND BLACK HOLE POPULATIONS: DUTY CYCLES, ACCRETION RATES, AND THE MEAN RADIATIVE EFFICIENCY

We construct evolutionary models of the populations of AGN and supermassive black holes, in which the black hole mass function grows at the rate implied by the observed luminosity function, given assumptions about the radiative efficiency and the Eddington ratio. We draw on a variety of recent X-ray and optical measurements to estimate the bolometric AGN luminosity function and compare to X-ray background data and the independent estimate of Hopkins et al. (2007) to assess remaining systematic uncertainties. The integrated AGN emissivity closely tracks the cosmic star formation history, suggesting that star formation and black hole growth are closely linked at all redshifts. Observational uncertainties in the local black hole mass function remain substantial, with estimates of the integrated black hole mass density \rho_BH spanning the range 3-5.5x10^5 Msun/Mpc^3. We find good agreement with estimates of the local mass function for a reference model where all active black holes have efficiency \eps=0.065 and L_bol/L_Edd~0.4. In this model, the duty cycle of 10^9 Msun black holes declines from 0.07 at z=3 to 0.004 at z=1 and 0.0001 at z=0. The decline is shallower for less massive black holes, a signature of "downsizing" evolution in which more massive black holes build their mass earlier. The predicted duty cycles and AGN clustering bias in this model are in reasonable accord with observational estimates. If the typical Eddington ratio declines at z<2, then the "downsizing" of black hole growth is less pronounced. Matching the integrated AGN emissivity to the local black hole mass density implies \eps=0.075 (\rho_BH/4.5x10^5 Msun/Mpc^3)^{-1} for our standard luminosity function estimate (25% higher for Hopkins et al.'s), lower than the values \eps=0.16-0.20 predicted by MHD simulations of disk accretion.

The central black hole and relationships with the host galaxy

More than 40 years ago, astronomers speculated that active galactic nuclei are fundamentally powered by accretion onto supermassive black holes. In this contribution, the basic observations and theoretical considerations that led to this conclusion are reviewed, as is emission-line reverberation mapping, which is now used to measure the masses of black holes in AGNs. Key correlations – the broad-line region radius–luminosity relationship and the relationships between black hole mass and host galaxy properties – are also discussed.

Neutrino radiation of the AGN black holes

In the framework of ‘microscopic’ theory of black holes (J. Phys. Soc. Jpn. Suppl. B 70, 84, 2001; Astrophys. USSR 4, 659, 1996; 35, 335, 1991, 33, 143, 1990, 31, 345, 1989a; Astrophys. Space Sci. 1, 1992; Dokl. Akad. Nauk USSR 309, 97, 1989b), and references therein, we address the ‘pre-radiation time’ (PRT) of neutrinos from black holes, which implies the lapse of time from black hole’s birth till radiation of an extremely high energy neutrinos. For post-PRT lifetime, the black hole no longer holds as a region of spacetime that cannot communicate with the external universe. We study main features of spherical accretion onto central BH and infer a mass accretion rate onto it, and, further, calculate the resulting PRT versus bolometric luminosity due to accretion onto black hole. We estimate the PRTs of AGN black holes, with the well-determined masses and bolometric luminosities, collected from the literature by Woo Jong-Hak and Urry (Astrophys. J. 579, 530, 2002) on which this paper is partially based. The simulations for the black holes of masses MBH≃(1.1⋅106÷4.2⋅109) M⊙ give the values of PRTs varying in the range of about TBH≃(4.3⋅105÷5.6⋅1011) yr. The derived PRTs for the 60 AGN black holes are longer than the age of the universe (∼13.7 Gyr) favored today. At present, some of remaining 174 BHs may radiate neutrinos. However, these results would be underestimated if the reservoir of gas for accretion in the galaxy center is quite modest, and no obvious way to feed the BHs with substantial accretion.

Opportunities for maser studies with the Square Kilometre Array

AbstractThe Square Kilometre Array (SKA) is the radio telescope of the next generation, providing an increase in sensitivity and angular resolution of two orders of magnitude over existing telescopes. Currently, the SKA is expected to span the frequency range 0.1-25 GHz with capabilities including a wide field-of-view and measurement of polarised emission. Such a telescope has enormous potential for testing fundamental physical laws and producing transformational discoveries. Important science goals include using H2O megamasers to make precise estimates of H0, which will anchor the extragalactic distance scale, and to probe the central structures of accretion disks around supermassive black holes in AGNs, to study OH megamasers associated with extreme starburst activity in distant galaxies and to study with unprecedented precision molecular gas and star formation in our Galaxy.

General Relativistic Radiative Transfer: Emission from Accreting Black Holes in AGN

We present two covariant radiative transfer formulations, and apply them to calculate emission from relativistic accretion flows around black holes. The first formulation is for situations with only line-of-sight absorption and emission, while the second formulation is for situations where scattering is important. We use the first formulation to calculate emissions from opaque accretion disks and tori around black holes absorbed by high-velocity cloudlets. Our calculations show the importance of effects due to space-time curvature, relativistic motions of the emitters and absorbers, and external line-of-sight absorption. We find that external absorption tends to take away line fluxes at energies red-ward of the line-centre energy. In its presence, emission lines from geometrically thin opaque relativistic accretion disks may not have broad asymmetric double-peak profiles: in some situations the lines may appear to be narrow, sharp and blue-shifted. We also find that geometric effects are important for thick accretion disks (accretion tori). When viewed at high inclination angles, the inner surface of an accretion torus can be self-occulted. As the most highly red-shifted and blue-shifted emissions are blocked, emission lines from an opaque accretion torus would suffer less broadening and the line intensities are less boosted. These lines may have single-peak profiles, but their line centres are slightly red-shifted. We apply the radiative transfer formulation to calculate emission lines from optically thin and semi-opaque accretion tori, and generalise it to calculate continua emission, such as the reflection spectra, of accretion disks. The second convariant radiative transfer formulation, which is based on a moment method, is used to calculate the emissions from accretion tori with the opacity being dominated by electron scattering. We demonstrate that the formulation is applicable for a wide range of optical depths appropriate for accretion tori around black holes.