Speaker
Description
Pulsars are remarkable astronomical tools — both as precise clocks for timing and as sources of polarized light. As clocks, millisecond pulsars have been used since the 1980s to form Pulsar Timing Arrays (PTAs) for detecting nanohertz gravitational waves. As polarized sources, the speaker and his collaborators have proposed constructing a Pulsar Polarization Array (PPA) to explore new astrophysical phenomena through a common polarization signal correlated on galactic scales. In this talk, the speaker will introduce these astronomical tools and discuss how the PPA, together with the PTA, can be applied to detect ultralight axion-like dark matter (ALDM). He will present the first limits on the ALDM Chern–Simons coupling to photons derived from the PPA, obtained by the Parkes PTA collaboration, and report progress from the MeerKAT Thousand-Pulsar Polarization Array. The discussion will also extend to PTA-based detections of ALDM, both with and without signal correlations across pulsars considered. Finally, the speaker will discuss the potential synergy between PTA and PPA in this search and outline directions for future exploration.