نتایج جستجو برای: black holes

تعداد نتایج: 158936  

2017
J. Casares

We discuss the method, and potential systematic effects therein, used for measuring the mass of stellar-mass black holes in X-ray binaries. We restrict our discussion to the method that relies on the validity of Kepler’s laws; we refer to this method as the dynamical method. We briefly discuss the implications of the mass distribution of stellar-mass black holes and provide an outlook for futur...

2008
Noam I. Libeskind Shaun Cole Carlos S. Frenk John C. Helly

Galactic bulges are known to harbour central black holes whose mass is tightly correlated with the stellar mass and velocity dispersion of the bulge. In a hierarchical universe, galaxies are built up through successive mergers of subgalactic units, a process that is accompanied by the amalgamation of bulges and the likely coalescence of galactocentric black holes. In these mergers, the beaming ...

2003
Sean A. Hartnoll

We study black holes in AdS-like spacetimes, with the horizon given by an arbitrary positive curvature Einstein metric. A criterion for classical instability of such black holes is found in the large and small black hole limits. Examples of large unstable black holes have a Böhm metric as the horizon. These, classically unstable, large black holes are locally thermodynamically stable. The gravi...

2008
Hongbao Zhang Zhoujian Cao Xuefei Gong Wei Zhou

We employ WKB approximation up to the third order to determine the low-lying quasinormal modes for Weyl neutrino field in R-N black holes, which are the most relevant to the evolution of the field around a black hole in the intermediate stage. It is showed that the quasinormal mode frequencies for Weyl neutrino field in R-N black holes are different from those in Schwartzchild black holes ownin...

1994
Valeri P. Frolov Lárus Thorlacius

V. Frolov and L. Thorlacius QUANTUM ASPECTS OF GRAVITY 2 S.B. Giddings and L. Thorlacius INTRODUCTION TO THE INFORMATION PROBLEM 6 A. Strominger TWO-DIMENSIONAL BLACK HOLES AND THE INFORMATION PUZZLE 9 V. Frolov ENTROPY OF BLACK HOLES 12 L. Thorlacius BLACK HOLE COMPLEMENTARITY 15 D.A. Lowe CAUSALITY IN STRING THEORY 18 A.O. Barvinski NONLOCAL EFFECTIVE ACTION AND BLACK HOLES 22 P.C. Argyres UN...

1999
Guinevere Kauffmann

We discuss constraints on the assembly history of supermassive black holes from the observed remnant black holes in nearby galaxies and from the emission caused by accretion onto these black holes. We also summarize the results of a specific model for the evolution of galaxies and their central black holes which traces their hierachical build-up in CDM-like cosmogonies. The model assumes (i) th...

2003
Troels Harmark

We find the metric of small black holes on cylinders, i.e. neutral and static black holes with a small mass in d-dimensional Minkowski-space times a circle. The metric is found using an ansatz for black holes on cylinders proposed in hep-th/0204047. We use the new metric to compute corrections to the thermodynamics which is seen to deviate from that of the (d + 1)-dimensional Schwarzschild blac...

2002
Andrei Barvinsky

Bekenstein proposed that the spectrum of horizon area of quantized black holes must be discrete and uniformly spaced. We examine this proposal in the context of spherically symmetric charged black holes in a general class of gravity theories. By imposing suitable boundary conditions on the reduced phase space of the theory to incorporate the thermodynamic properties of these black holes and the...

2003
Roberto Emparan Robert C. Myers

It has long been known that, in higher-dimensional general relativity, there are black hole solutions with an arbitrarily large angular momentum for a fixed mass [1]. We examine the geometry of the event horizon of such ultra-spinning black holes and argue that these solutions become unstable at large enough rotation. Hence we find that higher-dimensional general relativity imposes an effective...

2005
Yuan K. Ha

A new theorem for black holes is found. It is called the horizon mass theorem. The horizon mass is the mass which cannot escape from the horizon of a black hole. For all black holes: neutral, charged or rotating, the horizon mass is always twice the irreducible mass observed at infinity. Previous theorems on black holes are: 1. the singularity theorem, 2. the area theorem, 3. the uniqueness the...

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