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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Thermodynamic phase transition in the rainbow Schwarzschild black hole

We study the thermodynamic phase transition in the rainbow Schwarzschild black hole where the metric depends on the energy of the test particle. Identifying the black hole temperature with the energy from the modified dispersion relation, we obtain the modified entropy and thermodynamic energy along with the modified local temperature in the cavity to provide well defined black hole states. It is found that apart from the conventional critical temperature related to Hawking-Page phase transition there appears an additional critical temperature which is of relevance to the existence of a locally stable tiny black hole; however, the off-shell free energy tells us that this black hole should eventually tunnel into the stable large black hole. Finally, we discuss the reason why the temperature near the horizon is finite in the rainbow black hole by employing the running gravitational coupling constant, whereas it is divergent near the horizon in the ordinary Schwarzschild black hole.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

String scale black holes at large D

We study aspects of black holes near the Hagedorn temperature. The large dimension expansion introduced by Soda, Emparan, Grumiller and Tanabe connects them to the well studied two dimensional black hole based on SL(2) k /U(1). This allows us to explore black holes at string scale temperatures. We argue that the black hole can surpass the Hagedorn temperature, but at a somewhat larger temperature it is likely to turn over to a highly excited string.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Following black hole scaling relations through gas-rich mergers

We present black hole mass measurements from kinematic modeling of high-spatial resolution integral field spectroscopy of the inner regions of nine nearby (ultra-)luminous infrared galaxies in a variety of merger stages. These observations were taken with OSIRIS and laser guide star adaptive optics on the Keck I and Keck II telescopes, and reveal gas and stellar kinematics inside the spheres of influence of these supermassive black holes. We find that this sample of black holes are overmassive (∼10{sup 7–9} M) compared to the expected values based on black hole scaling relations, and suggest that the major epoch of black hole growth occurs in early stages of a merger, as opposed to during a final episode of quasar-mode feedback. The black hole masses presented are the dynamical masses enclosed in ∼25 pc, and could include gas which is gravitationally bound to the black hole but has not yet lost sufficient angular momentum to be accreted. If present, this gas could in principle eventually fuel active galactic nucleus feedback or be itself blown out from the system.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT

The anti-de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid, and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Horava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attention due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Horava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Horava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in {lambda} = 1 Horava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter {epsilon} close to unity. Sufficiently charged flat black holes for {epsilon} close to unity, and sufficiently charged positively curved black holes with {epsilon} close to zero, are also unstable. The implication to the Horava-Lifshitz holographic superconductor is discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

ACCRETION DISKS AROUND KICKED BLACK HOLES: POST-KICK DYNAMICS

Numerical calculations of merging black hole binaries indicate that asymmetric emission of gravitational radiation can kick the merged black hole at up to thousands of km s{sup -1}, and a number of systems have been observed recently whose properties are consistent with an active galactic nucleus containing a supermassive black hole moving with substantial velocity with respect to its broader accretion disk. We study here the effect of an impulsive kick delivered to a black hole on the dynamical evolution of its accretion disk using a smoothed particle hydrodynamics code, focusing attention on the role played by the kick angle with respect to the orbital angular momentum vector of the pre-kicked disk. We find that for more vertical kicks, for which the angle between the kick and the normal vector to the disk {theta} {approx}< 30 Degree-Sign , a gap remains present in the inner disk, in accordance with the prediction from an analytic collisionless Keplerian disk model, while for more oblique kicks with {theta} {approx}> 45 Degree-Sign , matter rapidly accretes toward the black hole. There is a systematic trend for higher potential luminosities for more oblique kick angles for a given black hole mass, disk mass, and kick velocity, and we find large amplitude oscillations in time in the case of a kick oriented 60 Degree-Sign from the vertical.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Strong gravitational lensing by the R-charged non-extremal black hole

The gravitational lensing scenario with the R-charged black hole of five-dimensional supergravity is being investigated. We study the effective potential of traveling photons near the R-charged black hole and find some stable orbits for the photons. We also find that the effect of the black hole charges resulted in an increase of the effective potential. We have shown that photons do not cross the horizon of the very large R-charged black hole. By using the numerical study, we find that the black hole charges and non-extremality parameter decrease value of the deflection angle. We also find effect of the black hole charges on the lens equation and observable in strong field limit and compare our results with Schwarzschild and Reissner–Nordstrom black holes.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Six-point functions and collisions in the black hole interior

In the eternal AdS black hole geometry, we consider two signals sent from the boundaries into the black hole interior shared between the two asymptotic regions. We compute three different out-of-time-order six-point functions to quantify various properties of the collision of these signals behind the horizons: (i) We diagnose the strength of the collision by probing the two-signal state on a late time slice with boundary operators. (ii) We quantify two-sided operator growth, which provides a dual description of the signals meeting in the black hole interior, in terms of the quantum butterfly effect and quantum circuits. (iii) We consider an explicit coupling between the left and right CFTs to make the wormhole traversable and extract information about the collision product from behind the horizon. At a technical level, our results rely on the method of eikonal resummation to obtain the relevant gravitational contributions to Lorentzian six-point functions at all orders in the GN-expansion. We observe that such correlation functions display an intriguing factorization property. We corroborate these results with geodesic computations of six-point functions in two- and three-dimensional gravity.

2D Gravity↗
DOE OSTI2016

The rigorous bound on the transmission probability for massless scalar field of non-negative-angular-momentum mode emitted from a Myers-Perry black hole

Hawking radiation is the evidence for the existence of black hole. What an observer can measure through Hawking radiation is the transmission probability. In the laboratory, miniature black holes can successfully be generated. The generated black holes are, most commonly, Myers-Perry black holes. In this paper, we will derive the rigorous bounds on the transmission probabilities for massless scalar fields of non-negative-angular-momentum modes emitted from a generated Myers-Perry black hole in six, seven, and eight dimensions. The results show that for low energy, the rigorous bounds increase with the increase in the energy of emitted particles. However, for high energy, the rigorous bounds decrease with the increase in the energy of emitted particles. When the black holes spin faster, the rigorous bounds decrease. For dimension dependence, the rigorous bounds also decrease with the increase in the number of extra dimensions. Furthermore, as comparison to the approximate transmission probability, the rigorous bound is proven to be useful.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

A 5 × 10{sup 9}M{sub ⊙} BLACK HOLE IN NGC 1277 FROM ADAPTIVE OPTICS SPECTROSCOPY

The nearby lenticular galaxy NGC 1277 is thought to host one of the largest black holes known, however the black hole mass measurement is based on low spatial resolution spectroscopy. In this paper, we present Gemini Near-infrared Integral Field Spectrometer observations assisted by adaptive optics. We map out the galaxy's stellar kinematics within ∼440 pc of the nucleus with an angular resolution that allows us to probe well within the region where the potential from the black hole dominates. We find that the stellar velocity dispersion rises dramatically, reaching ∼550 km s{sup −1} at the center. Through orbit-based, stellar-dynamical models we obtain a black hole mass of (4.9 ± 1.6) × 10{sup 9} M{sub ⊙} (1σ uncertainties). Although the black hole mass measurement is smaller by a factor of ∼3 compared to previous claims based on large-scale kinematics, NGC 1277 does indeed contain one of the most massive black holes detected to date, and the black hole mass is an order of magnitude larger than expectations from the empirical relation between black hole mass and galaxy luminosity. Given the galaxy's similarities to the higher redshift (z ∼ 2) massive quiescent galaxies, NGC 1277 could be a relic, passively evolving since that period. A population of local analogs to the higher redshift quiescent galaxies that also contain over-massive black holes may suggest that black hole growth precedes that of the host galaxy.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Quantum error correction in the black hole interior

We study the quantum error correction properties of the black hole interior in a toy model for an evaporating black hole: Jackiw-Teitelboim gravity entangled with a non-gravitational bath. After the Page time, the black hole interior degrees of freedom in this system are encoded in the bath Hilbert space. We use the gravitational path integral to show that the interior density matrix is correctable against the action of quantum operations on the bath which (i) do not have prior access to details of the black hole microstates, and (ii) do not have a large, negative coherent information with respect to the maximally mixed state on the bath, with the lower bound controlled by the black hole entropy and code subspace dimension. Thus, the encoding of the black hole interior in the radiation is robust against generic, low-rank quantum operations. For erasure errors, gravity comes within an O (1) distance of saturating the Singleton bound on the tolerance of error correcting codes. For typical errors in the bath to corrupt the interior, they must have a rank that is a large multiple of the bath Hilbert space dimension, with the precise coefficient set by the black hole entropy and code subspace dimension.

2D gravity↗
DOE OSTI2019

C iv black hole mass measurements with the Australian Dark Energy Survey (OzDES)

ABSTRACT Black hole mass measurements outside the local Universe are critically important to derive the growth of supermassive black holes over cosmic time, and to study the interplay between black hole growth and galaxy evolution. In this paper, we present two measurements of supermassive black hole masses from reverberation mapping (RM) of the broad C iv emission line. These measurements are based on multiyear photometry and spectroscopy from the Dark Energy Survey Supernova Program (DES-SN) and the Australian Dark Energy Survey (OzDES), which together constitute the OzDES RM Program. The observed reverberation lag between the DES continuum photometry and the OzDES emission line fluxes is measured to be $358^{+126}_{-123}$ and $343^{+58}_{-84}$ d for two quasars at redshifts of 1.905 and 2.593, respectively. The corresponding masses of the two supermassive black holes are 4.4 × 109 and 3.3 × 109 M⊙, which are among the highest redshift and highest mass black holes measured to date with RM studies. We use these new measurements to better determine the C iv radius−luminosity relationship for high-luminosity quasars, which is fundamental to many quasar black hole mass estimates and demographic studies.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2000

Black Holes Shed Light on Galaxy Formation

This videotape is comprised of several segments of animations on black holes and galaxy formation, and several segments of an interview with Dr. John Kormendy. The animation segments are: (1) a super massive black hole, (2) Centarus A active black hole found in a collision, (3) galaxy NGC-4261 (active black hole and jet model), (4) galaxy M-32 (orbits of stars are effected by the gravity of the black hole), (5) galaxy M-37 (motion of stars increases as mass of black hole increases), (6) Birth of active galactic nuclei, (7) the collision of two galaxy leads to merger of the black holes, (8) Centarus A and simulation of the collision of 2 galaxies. There are also several segments of an interview with John Kormendy. In these segments he discusses the two most important aspects of his recent black hole work: (1) the correlations between galaxies speed and the mass of the black holes, and (2) the existence of black holes and galactic formation. He also discusses the importance of the Hubble Space Telescope and the Space Telescope Imaging Spectrograph to the study of black holes. He also shows the methodology of processing images from the spectrograph in his office.

Source record↗
DOE OSTI2019

First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole

When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux ratio gsim10:1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 ± 0.7) × 109 M⊙. Our radio-wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Spins of primordial black holes formed in different cosmological scenarios

Primordial black holes (PBHs) could account for all or part of dark matter, as well as for some LIGO events. We discuss the spins of primordial black holes produced in different cosmological scenarios, with the emphasis on recently discovered possibilities. PBHs produced as a horizon-size collapse of density perturbations are known to have very small spins. In contrast, PBHs resulting from assembly of matterlike objects (particles, Q-balls, oscillons, etc.) can have large or small spins depending on their formation history and the efficiency of radiative cooling. Here, we show that scalar radiation can remove the angular momentum very efficiently, leading to slowly rotating PBHs in those scenarios for which the radiative cooling is important. Gravitational waves astronomy offers an opportunity to determine the spins of black holes, opening a new window on the early Universe if, indeed, some black holes have primordial origin.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Black hole superradiance with dark matter accretion

Studies of black hole superradiance often focus on the growth of a cloud in isolation, accompanied by the spin-down of the black hole. Here, in this paper, we consider the additional effect of the accretion of matter and angular momentum from the environment. We show that, in many cases, the black hole evolves by drifting along the superradiance threshold, in which case the evolution of its parameters can be described analytically or semianalytically. We quantify the conditions under which accretion can serve as a mechanism to increase the cloud-to-black hole mass ratio, beyond the standard maximum of about 10%. This occurs by a process we call oversuperradiance, whereby accretion effectively feeds the superradiance cloud, by way of the black hole. We give two explicit examples: accretion from a vortex expected in wave dark matter and accretion from a baryonic disk. In the former case, we estimate the accretion rate by using an analytical fit to the asymptotic behavior of the confluent Heun function. Level transition, whereby one cloud level grows while the other shrinks, can be understood in a similar way.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Clusters of primordial black holes and reionization problem

Clusters of primordial black holes may cause the formation of quasars in the early Universe. In turn, radiation from these quasars may lead to the reionization of the Universe. However, the evaporation of primordial black holes via Hawking’s mechanism may also contribute to the ionization of matter. The possibility of matter ionization via the evaporation of primordial black holes with allowance for existing constraints on their density is discussed. The contribution to ionization from the evaporation of primordial black holes characterized by their preset mass spectrum can roughly be estimated at about 10{sup −3}.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Statistical physics of black holes as quantum-mechanical systems

Some basic features of black-hole statistical mechanics are investigated, assuming that black holes respect the principles of quantum mechanics. Care is needed in defining an entropy S bh corresponding to the number of microstates of a black hole, given that the black hole interacts with its surroundings. An open question is then the relationship between this entropy and the Bekenstein-Hawking entropy S BH . For a wide class of models with interactions needed to ensure unitary quantum evolution, these interactions produce extra energy flux beyond that predicted by Hawking. Arguments are then presented that this results in an entropy S bh that is smaller than S BH . Correspondingly, in such scenarios equilibrium properties of black holes are modified. In this work, we examine questions of consistency of such an inequality; if it is not consistent, that provides significant constraints on models for quantum-mechanical black hole evolution.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Effect of magnetic field inclination on black hole jet power and particle acceleration

Rotating black holes are known to launch relativistic jets and accelerate particles if they accrete a magnetized plasma. It remains unclear, however, how the global magnetic field orientation affects the jet powering efficiency. We propose the first kinetic study of a collisionless plasma around a Kerr black hole embedded in a magnetic field that is inclined with respect to the black hole spin axis. Using three-dimensional general relativistic particle-in-cell simulations, we show that while oblique magnetic field configurations significantly reduce the jet power, particle acceleration still remains highly efficient. This suggests that black holes producing a weak jet might still be bright sources of nonthermal radiation and cosmic rays.

acceleration of particles↗