Enhanced exploration for primordial black holes using pulsar timing arrays

Abstract

We investigate the capability of pulsar timing arrays 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 Square Kilometre Array could detect PBHs with masses around ∼1022-28g even if only a small fraction (≲1 per cent) of the Galactic dark matter consists of these PBHs. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.