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The dark matter (DM) can consist of the primordial black holes (PBHs) in addition to the conventional weakly interacting massive particles (WIMPs). The Poisson fluctuations of the PBH number density produce the isocurvature perturbations which can dominate the matter power spectrum at small scales and enhance the early structure formation. We study how the WIMP annihilation from those early formed structures can affect the CMB (in particular the E-mode polarization anisotropies and $y$-type spectral distortions) and global 21cm signals. Our studies would be of particular interest for the light (sub-GeV) WIMP scenarios which have been less explored compared with the mixed DM scenarios consisting of PBHs and heavy ($gtrsim 1$ GeV) WIMPs. For instance, for the self-annihilating DM mass $m_{chi}=1$ MeV and the thermally averaged annihilation cross section $langle sigma v rangle sim 10^{-30} rm cm^3/s$, the latest Planck CMB data requires the PBH fraction with respect to the whole DM to be at most ${cal O}(10^{-3})$ for the sub-solar mass PBHs and an even tighter bound (by a factor $sim 5$) can be obtained from the global 21-cm measurements.
Primordial black holes (PBHs) are those which may have formed in the early Universe and affected the subsequent evolution of the Universe through their Hawking radiation and gravitational field. To constrain the early Universe from the observational
Primordial black holes (PBHs) in the mass range $(30$--$100)~M_{odot}$ are interesting candidates for dark matter, as they sit in a narrow window between microlensing and cosmic microwave background constraints. There are however tight constraints fr
We show that the number of primordial black holes (PBHs) which is originated from primordial density perturbations with moderately-tilted power spectrum fluctuates following the log-normal distribution, while it follows the Poisson distribution if th
The merger rate of primordial black holes depends on their initial clustering. In the absence of primordial non-Gaussianity correlating short and large-scales, primordial black holes are distributed `a la Poisson at the time of their formation. Howev
Primordial black holes could have been formed in the early universe from non linear cosmological perturbations re-entering the cosmological horizon when the Universe was still radiation dominated. Starting from the shape of the power spectrum on supe