Enhanced exploration for primordial black holes using pulsar timing
  arrays
  We investigate the capability of pulsar timing arrays (PTAs) as a probe of
primordial black holes (PBHs), which might constitute the Galactic dark matter.
A PBH passing nearby the Earth or a pulsar gives an impulse acceleration and
induces residuals on otherwise orderly pulsar timing data. We show that the
timing residuals induced at pulsars are optimal for searching heavier PBHs than
those at the Earth, and the two probes are highly complemental. Future
facilities like SKA could detect PBHs with masses around 10^(22-28) g even if
only a small fraction (< 1%) of the Galactic dark matter consists of these
PBHs.
