LIGO gravitational wave detection, primordial black holes and the
  near-IR cosmic infrared background anisotropies
  LIGO's discovery of a gravitational wave from two merging black holes (BHs)
of similar masses rekindled suggestions that primordial BHs (PBHs) make up the
dark matter (DM). If so, PBHs would add a Poissonian isocurvature density
fluctuation component to the inflation-produced adiabatic density fluctuations.
For LIGO's BH parameters, this extra component would dominate the small-scale
power responsible for collapse of early DM halos at z>10, where first luminous
sources formed. We quantify the resultant increase in high-z abundances of
collapsed halos that are suitable for producing the first generation of stars
and luminous sources. The significantly increased abundance of the early halos
would naturally explain the observed source-subtracted near-IR cosmic infrared
background (CIB) fluctuations, which cannot be accounted for by known galaxy
populations. For LIGO's BH parameters this increase is such that the observed
CIB fluctuation levels at 2 to 5 micron can be produced if only a tiny fraction
of baryons in the collapsed DM halos forms luminous sources. Gas accretion onto
these PBHs in collapsed halos, where first stars should also form, would
straightforwardly account for the observed high coherence between the CIB and
unresolved cosmic X-ray background in soft X-rays. We discuss modifications
possibly required in the processes of first star formation if LIGO-type BHs
indeed make up the bulk or all of DM. The arguments are valid only if the PBHs
make up all, or at least most, of DM, but at the same time the mechanism
appears inevitable if DM is made of PBHs.
