Are black holes totally black?

Grib, A. A.; Pavlov, Yu. V.

doi:10.1134/s0202289315010065

Cited by 42 publications

(45 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Account for more involved scenarios in which particles intermediate between the critical and usual ones participate, only confirmed this conclusion [14]. (There is another option when collision occurs near a white black hole [15] but we do not discuss here these rather exotic objects. )…”

Section: Quarks-2016mentioning

confidence: 72%

High energy particle collisions near black holes

Заславский

2016

EPJ Web Conf.

View full text Add to dashboard Cite

Abstract. If two geodesic particles collide near a rotating black hole, their energy in the centre of mass frame E c.m. can become unbound under certain conditions (the so-called BSW effect). The special role is played here by so-called critical geodesics when one of particles has fine-tuned energy and angular momentum. The nature of geodesics reveals itself also in fate of the debris after collisions. One of particles moving to a remote observer is necessarily near-critical. We discuss, when such a collision can give rise not only unboud E c.m. but also unbound Killing energy E (so-called super-Penrose process).Investigation of high energy collisions of particles near black holes comes back to works [1] - [3]. In recent years, an interest to this issue revived after the observation made by Bañados, Silk and West (the BSW effect, after the names of its authors) that particle collision near the Kerr black hole can lead, under certain additional conditions, to the unbounded growth of the energy in their centre of mass E c.m. [4]. Later on, in a large series of works, this observation was generalized and extended to other objects and scenarios. The energy that appears in the BSW effect is relevant for an observer who is present just near the point of collision in the vicinity of the black hole horizon. Meanwhile, what is especially physically important is the Killing energy E of debris after such a collision measured by an observer at infinity. Strong redshift "eats" significant part of E c.m. , so it was not quite clear in advance, to what extent the energy E may be high. If E exceeds the initial energy of particles, we are faced with the energy extraction from a black hole. This is a so-called collisional Penrose process (the Penrose process that occurs due to particle collisions). Thus there are two related but different issues: (i) investigation of the effect of unbounded E c.m. , (ii) study of properties of E and the question about the maximum possible efficiency of the collisional Penrose process.Consider the generic axially symmetric metric. It can be written asHere, the metric coefficients do not depend on t and φ. On the horizon N = 0. Alternatively, one can use coordinates θ and r, similar to Boyer-Lindquist ones for the Kerr metric, instead of l and z. In (1) we assume that the metric coefficients are even functions of z, so the equatorial plane θ = π 2 (z = 0) is a symmetry one.In the space-time under discussion there are two conserved quantities u 0 ≡ −E and u φ ≡ L where u μ = dx μ dτ is the four-velocity of a test particle, τ is the proper time and x μ = (t, φ, l, z) are coordinates..The aforementioned conserved quantities have the physical meaning of the energy per unit mass (or frequency for a lightlike particle) and azimuthal component of the angular momentum,

show abstract

Section: Quarks-2016mentioning

confidence: 72%

High energy particle collisions near black holes

Заславский

2016

EPJ Web Conf.

View full text Add to dashboard Cite

show abstract

“…If a naked singularity has been formed due to gravitational collapse with rotation, then we can explain the emergence in the ergosphere, from a region inside the gravitational radius, of not only Penrose geodesics but also the so-called white hole geodesics which have been classified in [10].…”

Section: Resultsmentioning

confidence: 99%

Naked singularity formation in generalized Vaidya space-time

Vertogradov

2016

Gravit. Cosmol.

View full text Add to dashboard Cite

The gravitational collapse in generalized Vaidya space-time is considered. It is known that the end state of gravitational collapse, as to whether a black hole or a naked singularity is formed, depends on the mass function M (v, r). Here we give conditions for the mass function which correspond to the equation of the state P = αρ. where α ∈ (0, 1/3], and according to these conditions we obtain either a black hole or a naked singularity as the end state of gravitational collapse. We also give the conditions for the mass function under which the singularity is gravitationally strong. We present simple examples showing when the result of gravitational collapse is a naked singularity and when this singularity is strong.

show abstract

“…The phenomenon of particle creation in an expanding universe has been studied by several authors [17][18][19][20][21][22][23][24][25][26]. One of the most interesting results is that in a radiation dominated universe there is exactly no creation of massless particles [27], either of zero or non-zero spin.…”

Section: General Theory Of Scalar Particle Creationmentioning

confidence: 99%

“…In the description of particle production by the gravitational field, a widely used method is that of instantaneous Hamiltonian diagonalization [23] suggested by Grib and Mamayev [25]. Of particular interest are the works relating the gravitational particle production at the end of inflation as a possible mechanism to produce super-heavy particles of dark matter [24,28].…”

Section: General Theory Of Scalar Particle Creationmentioning

confidence: 99%

Particle creation in a $$f(R)$$ f ( R ) theory with cosmological constraints

Pereira

Holanda

2014

Gen Relativ Gravit

View full text Add to dashboard Cite

In this paper we study the creation of super-massive real scalar particles in the framework of a f (R) = R − β/R n modified gravity theory, with parameters constrained by observational data.The analysis is restrict to a homogeneous and isotropic flat and radiation dominated universe. We compare the results to the standard Einstein gravity with cosmological constant (ΛCDM model), and we show that the total number density of created particles in the f (R) model is very close to the standard case. Another interesting result is that the spectrum of created particles is β independent at early times.

show abstract

Are black holes totally black?

Cited by 42 publications

References 20 publications

High energy particle collisions near black holes

High energy particle collisions near black holes

Naked singularity formation in generalized Vaidya space-time

Particle creation in a $$f(R)$$ f ( R ) theory with cosmological constraints

Contact Info

Product

Resources

About