Constraining and constructing mass distributions of Primordial Black
  Holes from 21cm signal
  The evaporation of Primordial Black Hole (PBH) via Hawking radiation
influences the evolution of Inter Galactic Medium by heating up the latter and
consequently affects the 21cm signal originated from the neutral Hydrogen
atoms. In this work, we have considered EDGES observational data of 21cm line
corresponding to cosmic dawn era to constrain the mass and the abundance of
PBHs. In this context, three different PBH mass distributions namely,
monochromatic, power law and lognormal mass distributions are considered to
estimate the effects of PBH evaporation on the 21cm brightness temperature
$T_{21}$. The impacts of Dark Matter - baryon interactions on $T_{21}$ are also
considered in this work along with the influences of PBH evaporation. Further
an attempt has been made in this work to formulate a mass distribution
expression for the PBHs in the context of the 21cm results considered here. The
mass distribution best suited for the present purpose is found to be a
combination of an error function and Owen function. Bounds on Dark Matter mass
are also calculated in this work by considering the PBH mass distributions.
