263 research outputs found
Adiabatic contraction revisited: implications for primordial black holes
We simulate the adiabatic contraction of a dark matter (DM) distribution
during the process of the star formation, paying particular attention to the
phase space distribution of the DM particles after the contraction. Assuming
the initial uniform density and Maxwellian distribution of DM velocities, we
find that the number of DM particles within the radius scales like
, leading to the DM density profile , in agreement with the Liouville theorem and previous numerical
studies. At the same time, the number of DM particles with periastra
smaller than is parametrically larger, , implying that
many particles contributing at any given moment into the density at
small have very elongated orbits and spend most of their time at distances
larger than . This has implications for the capture of DM by stars in the
process of their formation. As a concrete example we consider the case of
primordial black holes (PBH). We show that accounting for very eccentric orbits
boosts the amount of captured PBH by a factor of up to depending
on the PBH mass, improving correspondingly the previously derived constraints
on the PBH abundance.Comment: 8 pages, 3 figures, discussions added to the "Simulation of DM
orbits" part, fig.3 with several DM densities. Revised version to match
published versio
Possibility of hypothetical stable micro black hole production at future 100 TeV collider
We study the phenomenology of TeV-scale black holes predicted in theories
with large extra dimensions, under the further assumption that they are
absolutely stable. Our goal is to present an exhaustive analysis of safety of
the proposed 100 TeV collider, as it was done in the case of the LHC. We
consider the theories with different number of extra dimensions and identify
those for which a possible accretion to macroscopic size would have timescales
shorter than the lifetime of the Solar system. We calculate the cross sections
of the black hole production at the proposed 100 TeV collider, the fraction of
the black holes trapped inside the Earth and the resulting rate of capture
inside the Earth via an improved method. We study the astrophysical
consequences of stable micro black holes existence, in particular its influence
on the stability of white dwarfs and neutron stars. We obtain constraints for
the previously unexplored range of higher-dimensional Planck mass values.
Several astrophysical scenarios of the micro black hole production, which were
not considered before, are taken into account. Finally, using the astrophysical
constraints we consider the implications for future 100 TeV terrestrial
experiments. We exclude the possibility of the charged stable micro black holes
production.Comment: 11 pages, 8 figures, accepted for publication in EPJ
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