MUNA Lunch Talk:

Joris Verbiest

Swinburne University

Long-Term Timing of Milli-Second Pulsars and a Highly Precise Distance to PSR J0437-4715

July 14

12:10PM, Room 230, NRAO, Edgemont Road


A decade after the successful Parkes 70 cm pulsar survey, the archival timing data on 20 of the most precisely timed milli-second pulsars (MSPs) have been combined into one of the biggest long-term precision timing campaigns to date. Specifically, the timing of PSR J0437-4715 at 200ns precision over 10 years has resulted in one of the most precise distance measurements so far achieved in astronomy, placing the pulsar at a distance of 157.0 +/- 2.4 pc (1.5% precision). While this kinematic distance (derived from the pulsar proper motion and related Shklovskii effect on the orbital period) is consistent with that derived from the pulsar timing parallax, it has now also been verified by a VLBI parallax measurement at <1% precision. While interesting in itself, these independent distances can also be translated into a limit on the time variation of Newton's Gravitational constant, G, and can be used to constrain trans-Neptunian objects along the line of sight to the pulsar. Beyond the interest in individual pulsars, the data set as a whole provides information on the long-term stability of MSPs at micro- and submicro-second precision. Demonstrating the achievability of such precision on decadal timescales is a crucial first step towards the detection of gravitational waves through pulsar timing, as attempted in global timing array efforts.