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【摘要】

In this work, we assessed the sensitivity of SKA-like pulsar timing measurements to probe signals of a first order phase transition (FOPT) in the early Universe, triggered by dark sector dynamics. The FOPT leads to the formation of primordial black holes (PBHs), formed from collapsed Fermi balls created from filtered-out dark matter. We considered the Doppler phase shift in the pulsar timing signal, induced by the passage of these PBHs, as a probe of these objects. Under certain conditions, we found that critical temperatures of interest lie in the 0.1-10 keV range. We also proposed the idea that a simultaneous search of stochastic gravitational waves (GWs), produced during the FOPT, can be used as a complementary probe to investigate this hypothetical FOPT scenario in the early Universe. Finally, by considering an explicit form for the dark scalar potential, we performed a parameter scan to identify the subset of generic quartic potentials that could lead to FOPTs, which can be probed by pulsar timing and GW searches. The results of our scan may provide a useful reference to readily obtain phenomenological constraints on specific models that give rise to FOPTs.