Bayesian forecasts for dark matter substructure searches with mock pulsar timing data

Dark matter substructure, such as primordial black holes (PBHs) and axion miniclusters, can induce phase shifts in pulsar timing arrays (PTAs) measurements due to gravitational effects. In order to gain a more realistic forecast for the detectability of such models of dark matter with PTAs, we propose a Bayesian inference framework to search for phase shifts generated by PBHs and perform the analysis on mock PTA data. For most PBH masses the constraints on the dark matter abundance agree with previous (frequentist) analyses (without mock data) to O(1) factors. This further motivates a dedicated search for PBHs (and dense small scale structures) in the mass range from 10(-8)M(circle dot) to well above 10(2)M(circle dot) with the Square Kilometer Array. Moreover, with a more optimistic set of timing parameters, future PTAs are predicted to constrain PBHs down to 10(-11)M(circle dot). Lastly, we discuss the impact of backgrounds, such as Supermassive Black Hole Mergers, on detection prospects, suggesting a future program to separate a dark matter signal from other astrophysical sources.

Automated summary

A Bayesian inference framework is proposed to search for phase shifts generated by primordial black holes and provide a more realistic forecast for the detectability of such dark matter models using pulsar timing arrays. Constraints on dark matter abundance for most primordial black hole masses agree with previous analyses, motivating a dedicated search for such structures. Future pulsar timing arrays are predicted to constrain primordial black holes down to 10(-11) solar masses, with discussions on the impact of backgrounds like Supermassive Black Hole Mergers.