135 citations · 984 across the 46 of their papers we have counts for
46 papers
Extremal Kerr Black Hole Dark Matter from Hawking Evaporation
Quinn Taylor, Glenn D. Starkman, Michael Hinczewski +3
The Hawking process results in a monotonic decrease of the black hole mass, but a biased random walk of the black hole angular momentum. We demonstrate that this stochastic process…
Quasi-extremal primordial black holes are a viable dark matter candidate
Jose A. de Freitas Pacheco, Elias Kiritsis, Matteo Lucca +1
Black hole evaporation is generally considered inevitable for low-mass black holes, yet there is no confirmation of this remarkable hypothesis. Here, we propose a phenomenological…
Causality and the Arrow of Time in the Branch-Cut Cosmology
Benno Bodmann, César A. Zen Vasconcellos, José de Freitas Pacheco +2
We basis our initial analysis of the arrow of time on a relationship between the time evolution operator of quantum system and the time-independent density operator which describes…
Branch-Cut Cosmology and the Bekenstein Criterion
José A. de Freitas Pacheco, César A. Zen Vasconcellos, Peter O. Hess +2
In this contribution we address the implications of the Bekenstein Criterion in the branch-cut cosmology. The impossibility of packaging energy and entropy according to the Bekenst…
Primordial Rotating Black Holes
J. A. de Freitas Pacheco, Joseph Silk
Primordial black holes formed in an early post-inflation matter-dominated epoch during preheating provide a novel pathway for a source of the dark matter that utilizes known physic…
Supermassive Black Holes in the Early Universe
José Antonio de Freitas Pacheco
The discovery of high redshift quasars represents a challenge to the origin of supermassive black holes. Here, two evolutionary scenarios are considered. The first one concerns mas…
Quasi-normal modes of black holes and naked singularities: revisiting the WKB method
Edison C. Santos, Júlio C. Fabris, José A. de Freitas Pacheco
In this paper we revisit the analysis of the ringdown frequencies in the form of quasi-normal modes for Schwarzschild,Schwarzschild de-Sitter and Reissner-Nordström space-times. We…
Gravitational waves from binary axionic black holes
J. A. de Freitas Pacheco, S. Carneiro, J. C. Fabris
In a recent paper we have shown that a minimally coupled, self-interacting scalar field of mass can form black holes of mass (in Planck units). If dark matter…
Dark matter velocity dispersion effects on CMB and matter power spectra
O. F. Piattella, L. Casarini, J. C. Fabris +1
Effects of velocity dispersion of dark matter particles on the CMB TT power spectrum and on the matter linear power spectrum are investigated using a modified CAMB code. Cold dark…
Testing two alternatives theories to dark matter with the Milky Way dynamics
P. L. C. de Oliveira, J. A. de Freitas Pacheco, G. Reinisch
Two alternative theories to dark matter are investigated by testing their ability to describe consistently the dynamics of the Milky Way. The first one refers to a modified gravity…
Is the continuous matter creation cosmology an alternative to CDM?
J. C. Fabris, J. A. de Freitas Pacheco, O. F. Piattella
The matter creation cosmology is revisited, including the evolution of baryons and dark matter particles. The creation process affects only dark matter and not baryons. The dynamic…
Revisiting the Formation Rate and the Redshift Distribution of LGRBs
Chadia Kanaan, Jose A. de Freitas Pacheco
Using a novel approach, the distribution of fluences of long gamma ray bursts derived from the Swift-BAT catalog, was reproduced by a jet-model characterized by the distribution of…
Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation
Oliver F. Piattella, Davi C. Rodrigues, Júlio C. Fabris +1
We discuss solutions of Vlasov-Einstein equation for collisionless dark matter particles in the context of a flat Friedmann universe. We show that, after decoupling from the primor…
PS1-10jh - a tidal disruption event with an extremely low disk temperature
Matias Montesinos, J. A. de Freitas Pacheco
The cooler than expected optical-UV transient PS1-10jh detected by the Pan-STARRS1 survey is probably related to a tidal disruption event in which a He-rich stellar core remnant is…
Gravitational Model of High Energy Particles in a Collimated Jet
J. A. de Freitas Pacheco, J. Gariel, G. Marcilhacy +1
Observations suggest that relativistic particles play a fundamental role in the dynamics of jets emerging from active galactic nuclei as well as in their interaction with the intra…
The Evolution of the Baryon Distribution in the Universe from Cosmological Simulations
Fabrice Durier, Jose Antonio de Freitas Pacheco
The evolution of the baryon distribution in different phases, derived from cosmological simulations, are here reported. These computations indicate that presently most of baryons a…
Visser's Massive Gravity Bimetric Theory Revisited
Alain de Roany, Bertrand Chauvineau, J. A. de Freitas Pacheco
A massive gravity theory was proposed by Visser in the late nineties. This theory, based on a backgroung metric and on an usual dynamical metric has the advantage…
Relativistic Accretion into a Reissner-Nordström Black Hole Revisited
J. A. de Freitas Pacheco
The accretion of relativistic and non-relativistic fluids into a Reissner-Nordström black hole is revisited. The position of the critical point, the flow velocity at this point and…
Coalescence Rate of Supermassive Black Hole Binaries Derived from Cosmological Simulations: Detection Rates for LISA and ET
Ch. Filloux, J. A. de Freitas Pacheco, F. Durier +1
The coalescence history of massive black holes has been derived from cosmological simulations, in which the evolution of those objects and that of the host galaxies are followed in…
Hubble flow around Fornax cluster of galaxies
Olga G. Nasonova, José A. de Freitas Pacheco, Igor D. Karachentsev
Aims. This work aims to provide a new mass estimate for the Fornax cluster and the Fornax-Eridanus complex, avoiding methods like the virial or fits of X-ray emission profile, whic…
The Cosmological Constant and the Gravitational Light Bending
Tolu Biressa, J. A. de Freitas Pacheco
The solution of the null non-radial geodesic in a Schwarzschild-de Sitter background is revisited. The gravitational bending of a light ray is affected by the cosmological constant…
Tidal Disruption Flares: The Accretion Disk Phase
Matias Montesinos, José A. de Freitas Pacheco
The evolution of an accretion disk, formed as a consequence of the disruption of a star by a black hole, is followed by solving numerically the hydrodynamic equations. The present…
The growth of supermassive black holes fed by accretion disks
M. A. Montesinos, J. A. de Freitas Pacheco
Supermassive black holes are probably present in the centre of the majority of the galaxies. There is a consensus that these exotic objects are formed by the growth of seeds either…
Continuous matter creation and the acceleration of the universe: the growth of density fluctuations
Alain de Roany, J. A. de Freitas Pacheco
Cosmologies including continuous matter creation are able to reproduce the main properties of the standard CDM model, in particular in cases where the particle and entropy produ…