5 research outputs found
Consistency of the mass variation formula for black holes accreting cosmological fluids
We address the spherical accretion of generic fluids onto black holes. We
show that, if the black hole metric satisfies certain conditions, in the
presence of a test fluid it is possible to derive a fully relativistic
prescription for the black hole mass variation. Although the resulting equation
may seem obvious due to a form of it appearing as a step in the derivation of
the Schwarzschild metric, this geometrical argument is necessary to fix the
added degree of freedom one gets for allowing the mass to vary with time. This
result has applications on cosmological accretion models and provides a
derivation from first principles to serve as a base to the accretion equations
already in use in the literature.Comment: 4 pages, 1 figure. To appear in Gen. Rel. Gra
Brans-Dicke Theory and primordial black holes in Early Matter-Dominated Era
We show that primordial black holes can be formed in the matter-dominated era
with gravity described by the Brans-Dicke theory. Considering an early
matter-dominated era between inflation and reheating, we found that the
primordial black holes formed during that era evaporate at a quicker than those
of early radiation-dominated era. Thus, in comparison with latter case, less
number of primordial black holes could exist today. Again the constraints on
primordial black hole formation tend towards the larger value than their
radiation-dominated era counterparts indicating a significant enhancement in
the formation of primordial black holes during the matter-dominaed era.Comment: 9 page
Evolution of primordial black holes in a radiation and phantom energy environment
General Relativity and Gravitation, 40, pp. 1593-1602, http://dx.doi.org./10.1007/s10714-007-0562-8International audienc