Black Hole Luminosity Research Articles

Relating peak optical luminosity and orbital period of stellar-mass black holes in X-ray binaries

ABSTRACT We compare the peak optical luminosity with the orbital period for a sample of 22 stellar-mass black hole candidates with good measurements of both quantities. We find that the peak absolute magnitude for the outbursts follows a linear relation with MV, peak = 3.48(± 0.85) − 3.89(± 0.91) logPorb, which corresponds to a $L_V \propto P_{orb}^{1.56\pm 0.36}$ power-law relation. Excluding V4641 Sgr which is a strong outlier and not likely to have outbursts produced by the standard disc instability model, in addition to BW Cir and V821 Ara – both of which have highly uncertain distances; the new correlation for the 19 sources is found to be MV, peak = 3.01 (± 0.93) − 3.21 (± 1.04) logPorb, which corresponds to $L_V \propto P_{orb}^{1.28 \pm 0.42}$. This is an analogous relationship to the ‘Warner relation’ between orbital period and peak luminosity found for cataclysmic variables. We discuss the implications of these results for finding black hole X-ray binaries in other galaxies and in our own Galaxy with the Large Synoptic Survey Telescope and other future large time domain surveys.

On the origin of core radio emissions from black hole sources in the realm of relativistic shocked accretion flow

ABSTRACT We study the relativistic, inviscid, advective accretion flow around the black holes and investigate a key feature of the accretion flow, namely the shock waves. We observe that the shock-induced accretion solutions are prevalent and such solutions are commonly obtained for a wide range of the flow parameters, such as energy (${\cal E}$) and angular momentum (λ), around the black holes of spin value 0 ≤ ak < 1. When the shock is dissipative in nature, a part of the accretion energy is released through the upper and lower surfaces of the disc at the location of the shock transition. We find that the maximum accretion energies that can be extracted at the dissipative shock ($\Delta {\cal E}^{\rm max}$) are $\sim 1{{\ \rm per\ cent}}$ and $\sim 4.4{{\ \rm per\ cent}}$ for Schwarzschild black holes (ak → 0) and Kerr black holes (ak → 1), respectively. Using $\Delta {\cal E}^{\rm max}$, we compute the loss of kinetic power (equivalently shock luminosity, Lshock) that is enabled to comply with the energy budget for generating jets/outflows from the jet base (i.e. post-shock flow). We compare Lshock with the observed core radio luminosity (LR) of black hole sources for a wide mass range spanning 10 orders of magnitude with sub-Eddington accretion rate and perceive that the present formalism seems to be potentially viable to account LR of 16 Galactic black hole X-ray binaries (BH-XRBs) and 2176 active galactic nuclei. We further aim to address the core radio luminosity of intermediate-mass black hole (IMBH) sources and indicate that the present model formalism perhaps adequate to explain core radio emission of IMBH sources in the sub-Eddington accretion limit.

The shadow and observation appearance of black hole surrounded by the dust field in Rastall theory

In the context of Rastall gravity, the shadow and observation intensity casted by the new Kiselev-like black hole with dust field have been numerically investigated. In this system, the Rastall parameter and surrounding dust field structure parameter have considerable consequences on the geometric structure of spacetime. Considering the photon trajectories near the black hole, we investigate the variation of the radii of photon sphere, event horizon and black hole shadow under the different related parameters. Furthermore, taking into account two different spherically symmetric accretion models as the only background light source, we also studied the observed luminosity and intensity of black holes. For the both spherical accretions background, the results show that the decrease or increase of the observed luminosity depends on the value range of relevant parameters, and the promotion effect is far less obvious than the attenuation effect on the observed intensity. One can find that the inner shadow region and outer bright region of the black hole wrapped by infalling accretion are significantly darker than those of the static model, which is closely related to the Doppler effect. In addition, the size of the shadow and the position of the photon sphere are always the same in the two accretion models, which means that the black hole shadow depend only on the geometry of spacetime, while the observation luminosity is affected by the form of accretion material and the related spacetime structure.

Magnetically modified spherical accretion in GRMHD: reconnection-driven convection and jet propagation

ABSTRACT We present 3D general relativistic magnetohydrodynamic simulations of zero angular momentum accretion around a rapidly rotating black hole, modified by the presence of initially uniform magnetic fields. We consider several angles between the magnetic field direction and the black hole spin. In the resulting flows, the mid-plane dynamics are governed by magnetic reconnection-driven turbulence in a magnetically arrested (or a nearly arrested) state. Electromagnetic jets with outflow efficiencies ∼10–200 per cent occupy the polar regions, reaching several hundred gravitational radii before they dissipate due to the kink instability. The jet directions fluctuate in time and can be tilted by as much as ∼30○ with respect to black hole spin, but this tilt does not depend strongly on the tilt of the initial magnetic field. A jet forms even when there is no initial net vertical magnetic flux since turbulent, horizon-scale fluctuations can generate a net vertical field locally. Peak jet power is obtained for an initial magnetic field tilted by 40○–80○ with respect to the black hole spin because this maximizes the amount of magnetic flux that can reach the black hole. These simulations may be a reasonable model for low luminosity black hole accretion flows such as Sgr A* or M87.

Fundamental Reference AGN Monitoring Experiment (FRAMEx). I. Jumping Out of the Plane with the VLBA

Abstract We present the first results from the Fundamental Reference active galactic nucleus (AGN) Monitoring Experiment, an observational campaign dedicated to understanding the physical processes that affect the apparent positions and morphologies of AGNs. In this work, we obtained simultaneous Swift X-ray Telescope and Very Long Baseline Array (VLBA) radio observations for a snapshot campaign of 25 local AGNs that form a volume-complete sample with hard X-ray (14–195 keV) luminosities above 1042 erg s−1, out to a distance of 40 Mpc. Despite achieving an observation depth of ∼20 μJy, we find that 16 of 25 AGNs in our sample are not detected with the VLBA on milliarcsecond (subparsec) scales, and the corresponding core radio luminosity upper limits are systematically below predictions from the Fundamental Plane of black hole activity. Using archival Jansky Very Large Array (VLA) radio measurements, our sample jumps back onto the Fundamental Plane, suggesting that extended radio emission is responsible for the apparent correlation between radio emission, X-ray emission, and black hole mass. We suggest that this discrepancy is likely due to extranuclear radio emission produced via interactions between the AGN and host environment. We compare VLBA observations of AGNs to VLA observations of nearby Galactic black holes, and we find a mass-independent correlation between radio and X-ray luminosities of black holes of / ∼10−6, in line with predictions for coronal emission, but allowing for the possibility of truly radio-silent AGNs.

Accretion disc luminosity for black holes surrounded by dark matter

ABSTRACT We consider the observational properties of a static black hole space–time immersed in a dark matter envelope. We investigate how the modifications to geometry induced by the presence of dark matter affect the luminosity of the black hole’s accretion disc. We show that the same disc luminosity as produced by a black hole in vacuum may be produced by a smaller black hole surrounded by dark matter under certain conditions. In particular, we demonstrate that the luminosity of the disc is markedly altered by the presence of dark matter, suggesting that the mass estimation of distant supermassive black holes may be changed if they are immersed in dark matter. We argue that a similar effect holds in more realistic scenarios, and we discuss the refractive index related to dark matter lensing. Finally, we show how the results presented here may help to explain the observed luminosity of supermassive black holes in the early Universe.

Decoupling the rotation of stars and gas – II. The link between black hole activity and simulated IFU kinematics in IllustrisTNG

ABSTRACT We study the relationship between supermassive black hole (BH) feedback, BH luminosity, and the kinematics of stars and gas for galaxies in IllustrisTNG. We use galaxies with mock MaNGA observations to identify kinematic misalignment at z = 0 (difference in rotation of stars and gas), for which we follow the evolutionary history of BH activity and gas properties over the last 8 Gyr. Misaligned low-mass galaxies ($\mathrm{\mathit{ M}_{stel} \lt 10^{10.2}\, \mathrm{M}_{\odot }}$) typically have boosted BH luminosity and BH growth, and have had more energy injected by BHs into the gas over the last 8 Gyr in comparison to low-mass aligned galaxies. These properties likely lead to outflows and gas removal, in agreement with active low mass galaxies in observations. Splitting on BH luminosity at z = 0 produces consistent distributions of kinematic misalignment at z = 0; however, splitting on the maximum BH luminosity over the last 8 Gyr produces statistically significant different distributions. While instantaneous correlation at z = 0 is difficult due to misalignment persisting on longer time-scales, the relationship between BH activity and misalignment is clear. High-mass quenched galaxies ($\mathrm{\mathit{ M}_{stel} \gt 10^{10.2}\, \mathrm{M}_{\odot }}$) with misalignment typically have similar BH luminosities, show lower gas fractions, and have typically lower gas phase metallicity over the last 8 Gyr in comparison to the high mass aligned.

GUP black hole remnants in quadratic gravity

The Hawking radiation of static, spherically symmetric, asymptotically flat solutions in quadratic gravity is here scrutinized, in the context of the generalized uncertainty principle (GUP). Near-center and near-horizon Frobenius expansions of these solutions are studied. Their Hawking thermal spectrum is investigated out of the tunnelling method and the WKB procedure. Computing the Hawking flux of these black hole solutions shows that, for small black holes and for a precise combination of the GUP parameter and the parameters that govern the gravitational interaction in quadratic gravity, the black hole luminosity can vanish. This yields absolutely stable mini black hole remnants in quadratic gravity.

Effects of Strong Photospheric Dissipation on the Spectra and Structure of Accretion Disks with Nonzero Inner Torque

Abstract We present numerical calculations of spectra and structure of accretion disk models appropriate for near-Eddington luminosity black hole X-ray binaries. Our work incorporates nonzero torque at the ISCO as well as several dissipation profiles based on first-principles three-dimensional disk interior simulations. We found that significant dissipation near the photosphere can produce steep power-law-like spectra for models with moderate viewing angles spanning a range of black hole spins while including inner torque pushes the spectral peak to higher energies. Consistent with previous studies, we also conclude that disks with stresses at the inner edge remain viable models for high-frequency quasi-periodic oscillations, especially given that increasing dissipation near the photospheres actually resulted in QPO power spectra with higher quality factors compared to those found in recent work.

Supermassive black hole seed formation and the impact on black hole populations across cosmic time

AbstractAlthough it is well understood that supermassive black holes are found in essentially all galaxies, the mechanisms by which they initially form remain highly uncertain, despite the importance that the formation pathway can have on AGN and quasar behaviour at all redshifts. Using a post-processing analysis method combining cosmological simulations and analytic modeling, I will discuss how varying the conditions for formation of supermassive black hole seeds leads to changes in AGN populations. Looking at formation via direct collapse or from PopIII remnants, I will discuss the impact on black hole mass and luminosity functions, scaling relations, and black hole mergers, which each have effects at both high- and low-redshifts. In addition to demonstrating the importance of initial seed formation on our understanding of long-term black hole evolution, I will also show that the signatures of seed formation suggest multiple means by which upcoming electromagnetic and GW surveys (at both high- and low-z) can provide the data required to constrain initial supermassive black hole formation.

Quantum ergosphere and brick wall entropy

We revisit the “brick wall” model for black hole entropy taking into account backreaction effects on the horizon structure. We do so by adopting an evaporating metric in the quasi-static approximation in which departures from the standard Schwarzschild metric are governed by a small luminosity factor. One of the effects of the backreaction is to create an ergosphere-like region which naturally tames the usual divergence in the calculation of the partition function of the field. The black hole luminosity sets the width of such ‘quantum ergosphere’. We find a finite horizon contribution to the entropy which, for the luminosity associated to the Hawking flux, reproduces remarkably well the Bekenstein-Hawking entropy-area law.

Fast radio burst energetics and sources

Repeating and apparently non-repeating fast radio bursts (FRB) differ by orders of magnitude in duty factors, energy and rotation measure. Extensive monitoring of apparently non-repeating FRB has failed to find any repetitions. This suggests the two types differ qualitatively, rather than in repetition rate, and are produced by distinct kinds of sources. The absence of periodicity in repeating FRB argues that they are not produced by neutron stars. They may originate in dilute relativistic jets produced by low luminosity black hole accretion. Non-repeating FRB may be produced by catastrophic events such as the collapse of an accreting magnetic neutron star to a black hole or of an accreting magnetic white dwarf to a neutron star, during which a disappearing magnetic moment radiates dipole radiation that accelerates electrons in nearby matter. If they are emitted by collimated beams of relativistic particles or charge "bunches" with Lorentz factor $\gamma$, their radiation is collimated into a solid angle $\sim \gamma^{-2}$ sterad, reducing the energy requirement. If powered by magnetic reconnection, a pulse of length $\Delta t$ may draw on the magnetic energy in a volume $\sim \gamma^4 (c \Delta t)^3$, although only a fraction $\sim 1/\gamma^2$ of this may be dissipated without decollimation.

Quenching Black Hole Accretion by Active Galactic Nuclei Feedback

Abstract Observations of many dim galactic nuclei in the local universe give good estimations of gas density and temperature at the Bondi radius. If we assume the black hole accretes at the Bondi accretion rate and radiates at the efficiency of a low-luminosity hot accretion flow, the predicted nuclei luminosity can be significantly higher than that seen in observations. Therefore, the real black hole mass accretion rate in these sources may be significantly smaller than the Bondi value. Active galactic nucleus feedback may be responsible for decreasing the black hole accretion rate to values much smaller than the Bondi rate. We perform two-dimensional simulations of low-angular-momentum accretion flow at parsec and subparsec scales around low-luminosity active galactic nuclei (LLAGNs). We take into account the radiation and wind feedbacks of the LLAGN. The cross section of particle–particle interaction can be several orders of magnitude larger than that of photon–particle interaction. Therefore, we find that for the LLAGNs, the effects of radiation feedback in decreasing black hole accretion rates are small. However, wind feedback can effectively decrease the black hole mass accretion rate. Due to the decrease of the accretion rate, the black hole luminosity can be decreased by a factor of ∼33–400. These results may be useful for explaining why many galactic nuclei in the local universe are so dim.

The most powerful astrophysical events: Gravitational-wave peak luminosity of binary black holes as predicted by numerical relativity

For a brief moment, a binary black hole (BBH) merger can be the most powerful astrophysical event in the visible Universe. Here we present a model fit for this gravitational-wave peak luminosity of nonprecessing quasicircular BBH systems as a function of the masses and spins of the component black holes, based on numerical relativity (NR) simulations and the hierarchical fitting approach introduced by X. Jim\'enez-Forteza et al. [Phys. Rev. D 95, 064024 (2017).]. This fit improves over previous results in accuracy and parameter-space coverage and can be used to infer posterior distributions for the peak luminosity of future astrophysical signals like GW150914 and GW151226. The model is calibrated to the $\ensuremath{\ell}\ensuremath{\le}6$ modes of 378 nonprecessing NR simulations up to mass ratios of 18 and dimensionless spin magnitudes up to 0.995, and includes unequal-spin effects. We also constrain the fit to perturbative numerical results for large mass ratios. Studies of key contributions to the uncertainty in NR peak luminosities, such as (i) mode selection, (ii) finite resolution, (iii) finite extraction radius, and (iv) different methods for converting NR waveforms to luminosity, allow us to use NR simulations from four different codes as a homogeneous calibration set. This study of systematic fits to combined NR and large-mass-ratio data, including higher modes, also paves the way for improved inspiral-merger-ringdown waveform models.

Black hole radiation with modified dispersion relation in tunneling paradigm: Static frame

To study possible deviations from the Hawking's prediction, we assume that the dispersion relations of matter fields are modified at high energies and use the Hamilton–Jacobi method to investigate the corresponding effects on the Hawking radiation in this paper. The preferred frame is the static frame of the black hole. The dispersion relation adopted agrees with the relativistic one at low energies but is modified near the Planck mass mp. We calculate the corrections to the Hawking temperature for massive and charged particles to O(mp−2) and massless and neutral particles to all orders. Our results suggest that the thermal spectrum of radiations near horizon is robust, e.g. corrections to the Hawking temperature are suppressed by mp. After the spectrum of radiations near the horizon is obtained, we use the brick wall model to compute the thermal entropy of a massless scalar field near the horizon of a 4D spherically symmetric black hole. We find that the subleading logarithmic term of the entropy does not depend on how the dispersion relations of matter fields are modified. Finally, the luminosities of black holes are computed by using the geometric optics approximation.

Radiative, two-temperature simulations of low-luminosity black hole accretion flows in general relativity

We present a numerical method which evolves a two-temperature, magnetized, radiative, accretion flow around a black hole, within the framework of general relativistic radiation magnetohydrodynamics. As implemented in the code KORAL, the gas consists of two sub-components -- ions and electrons -- which share the same dynamics but experience independent, relativistically consistent, thermodynamical evolution. The electrons and ions are heated independently according to a standard prescription from the literature for magnetohydrodynamical turbulent dissipation. Energy exchange between the particle species via Coulomb collisions is included. In addition, electrons gain and lose energy and momentum by absorbing and emitting synchrotron and bremsstrahlung radiation, and through Compton scattering. All evolution equations are handled within a fully covariant framework in the relativistic fixed-metric spacetime of the black hole. Numerical results are presented for five models of low luminosity black hole accretion. In the case of a model with a mass accretion rate $\dot{M}\sim10^{-8} \dot M_{\rm Edd}$, we find that radiation has a negligible effect on either the dynamics or the thermodynamics of the accreting gas. In contrast, a model with a larger $\dot{M}\sim 4\times 10^{-4} \dot M_{\rm Edd}$ behaves very differently. The accreting gas is much cooler and the flow is geometrically less thick, though it is not quite a thin accretion disk.

Dependence of the Spin of Supermassive Black Holes on the Eddington Factor for Accretion Disks in Active Galactic Nuclei

An equation relating the spin of supermassive black holes (SMBH) to the Eddington factor, i.e., the ratio of the bolometric and Eddington luminosities for accretion disks in active galactic nuclei (AGN), is presented. This equation also depends on the relationship between the magnetic field pressure and the flux of accreted matter at the radius of the event horizon for a black hole. When the pressures of the magnetic field and of the accreted matter are equal, there is a direct relationship between the spin of the black hole and the Eddington factor. Based on available data on the bolometric luminosity and mass of black holes, it is possible to determine the spin of a black hole. The spins of the central SMBH are given for a number of AGN. The proposed method can also be used to determine the ratio of the magnetic field pressure and the pressure of the accreted gas at the event horizon of SMBH for AGN for which the spin of the black hole has been determined reliably.

Unveiling early black holes with JWST

AbstractThe formation of direct collapse black hole seeds with masses ~104 − 105 ~M⊙ could help explain the assembly of supermassive black holes powering high redshift quasars. Conditions conducive to the formation of these massive initial seeds exist at high redshift. Halos hosting these massive seeds merge promptly with a nearby galaxy. These early stage mergers at high redshift produce a new class of transient galaxies that contain an accreting black hole that is over-massive compared to the newly acquired stellar component - Obese Black hole Galaxies (OBGs). During this phase, the accretion luminosity of the direct collapse black hole seed exceeds that of the acquired stellar component. Here we calculate the multi-wavelength spectrum of this short-lived OBG stage, and show that there exist unique observational signatures in long wavelengths spanning near, mid to far-infrared that should be detectable by instruments aboard the upcoming James Webb Space Telescope (JWST).

X-RAY SOURCES IN THE DWARF SPHEROIDAL GALAXY DRACO

ABSTRACT We present the spectral analysis of an 87 ks XMM-Newton observation of Draco, a nearby dwarf spheroidal galaxy. Of the approximately 35 robust X-ray source detections, we focus our attention on the brightest of these sources, for which we report X-ray and multiwavelength parameters. While most of the sources exhibit properties consistent with active galactic nuclei, few of them possess the characteristics of low-mass X-ray binaries (LMXBs) and cataclysmic variable (CVs). Our analysis places constraints on the population of X-ray sources with L X > 3 × 1033 erg s−1 in Draco, suggesting that there are no actively accreting black hole and neutron star binaries. However, we find four sources that could be quiescent state LMXBs/CVs associated with Draco. We also place constraints on the central black hole luminosity and on a dark matter decay signal around 3.5 keV.

Thermodynamics and luminosities of rainbow black holes

Doubly special relativity (DSR) is an effective model for encoding quantum gravity in flat spacetime. As result of the nonlinearity of the Lorentz transformation, the energy-momentum dispersion relation is modified. One simple way to import DSR to curved spacetime is ``Gravity's rainbow'', where the spacetime background felt by a test particle would depend on its energy. Focusing on the ``Amelino-Camelia dispersion relation'' which is E2 = m2+p2[1−η(E/mp)n] with n > 0, we investigate the thermodynamical properties of a Schwarzschild black hole and a static uncharged black string for all possible values of η and n in the framework of rainbow gravity. It shows that there are non-vanishing minimum masses for these two black holes in the cases with η < 0 and n ⩾ 2. Considering effects of rainbow gravity on both the Hawking temperature and radius of the event horizon, we use the geometric optics approximation to compute luminosities of a 2D black hole, a Schwarzschild one and a static uncharged black string. It is found that the luminosities can be significantly suppressed or boosted depending on the values of η and n.