Pulsar Polarization Arrays

Liu Tao

Pulsar timing arrays (PTAs) consisting of widely distributed and well-timed millisecond pulsars can serve as a galactic interferometer to measure gravitational waves. With the same data acquired for PTAs, we propose to develop pulsar polarization arrays (PPAs), to explore astrophysics and fundamental physics. As in the case of PTAs, PPAs are best suited to reveal temporal and spatial correlations at large scales that are hard to mimic by local noise. As one demonstration of the PPAs’physical potential, we consider the detection of ultralight axion-like dark matter (ALDM; one of the most representative DM candidates) through the effect of cosmic birefringence. Because of its tiny mass, the ultralight ALDM can be generated as a Bose-Einstein condensate, characterized by a strong wave nature. Incorporating both temporal and spatial correlations of the signal, we show that the PPAs form a great complementarity with the existing ALDM detections in their sensitivity region.