ﻻ يوجد ملخص باللغة العربية
A perfect irrotational fluid with the equation of state of dust, Irrotational Dark Matter (IDM), is incapable of virializing and instead forms a cosmoskeleton of filaments with supermassive black holes at the joints. This stark difference from the standard cold dark matter (CDM) scenario arises because IDM must exhibit potential flow at all times, preventing shell-crossing from occurring. This scenario is applicable to general non-oscillating scalar-field theories with a small sound speed. Our model of combined IDM and CDM components thereby provides a solution to the problem of forming the observed billion-solar-mass black holes at redshifts of six and higher. In particular, as a result of the reduced vortical flow, the growth of the black holes is expected to be more rapid at later times as compared to the standard scenario.
Observations show that supermassive black holes (SMBHs) with a mass of $sim10^9 M_odot$ exist when the Universe is just $6%$ of its current age. We propose a scenario where a self-interacting dark matter halo experiences gravothermal instability and
Scalar-tensor theories of gravity generally violate the strong equivalence principle, namely compact objects have a suppressed coupling to the scalar force, causing them to fall slower. A black hole is the extreme example where such a coupling vanish
By examining the locations of central black holes in two elliptical galaxies, M,32 and M,87, we derive constraints on the violation of the strong equivalence principle for purely gravitational objects, i.e. black holes, of less than about two-thirds,
We discuss formation of dark matter (DM) mini-halos around primordial black holes (PBHs) and its implication on DM direct detection experiments, including axion searches. Motivated by LIGO observations, we consider $f_{textrm{DM}} simeq 0.01$ as the
The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has yielded unprecedented measurements of the soft gamma-ray spectrum of our Galaxy. Here we use those measurements to set constraints on dark matter (DM) that decays or annihil