Hao Ding (Mizusawa VLBI Observatory, National Astronomical Observatory of Japan)

Hao Ding's Colloquium: Enhancing the studies of reference frame ties and millisecond pulsar formation channels

Kensington/Teams

Abstract

Millisecond pulsars (MSPs) are the fastest-spinning neutron stars. Thanks to their superbtime-keeping ability, MSPs have provided sharp tests of gravitational theories, and have been collectively used to constrain the stochastic gravitational-wave background (GWB). Precise astrometric studies of MSPs are desired in many ways. In this talk, I will mainly focus on two scientific prospects promised by MSP astrometry. Firstly, as I will explain in the talk, the velocity distribution of MSPs is likely multi-modal. VLBI astrometry of MSPs holds the key to constraining the MSP velocity distribution, which is directly linked to the formation channels of MSPs. Secondly, VLBI and timing observations of MSPs can jointly refine the connection between the kinematic and dynamic reference frames, which would betterquantify the systematics in pulsar timing array studies. As the major VLBI network in the southern hemisphere, the Australian Long Baseline Array is crucial for significantly enriching the astrometrically studied MSP sample. I will introduce a new LBA program focusing on MSP astrometry, and update its progress. Alongside the scientific discussions, I will describe the main challenges the two studies are facing, and outline some innovations in data reduction and analysis that may help us overcome the challenges.