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Pulsar Timing at Parkes. George Hobbs CSIRO Australia Telescope National Facility george.hobbs@csiro.au. Purpose of talk. Highlight some recent results relating to pulsar timing and the Parkes Observatory Time constraints => will mainly concentrate on work that I’ve been involved in.
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Pulsar Timing at Parkes George Hobbs CSIRO Australia Telescope National Facility george.hobbs@csiro.au
Purpose of talk • Highlight some recent results relating to pulsar timing and the Parkes Observatory • Time constraints => will mainly concentrate on work that I’ve been involved in Large number of collaborators including: CASS pulsar group, PPTA team, Chinese pulsar community …. CSIRO. Gravitational wave detection
Pulsar timing Slide from D. Champion Fold Fold Model TOA (measured using the observatory clock) Residual CSIRO. Gravitational wave detection
A few simulations • With one pulsar you cannot (normally) tell what unmodelled physical effect is causing the residuals Clock noise GW background Spin-down irregularities Simulated data CSIRO. Gravitational wave detection
Spin-down irregularities No angular signature CSIRO. Gravitational wave detection
Terrestrial time standard irregularities Monopolar signature CSIRO. Gravitational wave detection
Errors in the planetary ephemerides - e.g. error in the mass of Jupiter Dipolar signature CSIRO. Gravitational wave detection
What if gravitational waves exist? Quadrapolar signature CSIRO. Gravitational wave detection
Studying individual pulsars using Parkes data • M. Yu et al. (in preparation) – detection of 105 glitches in 36 pulsars observed at Parkes • X. You et al. (in preparation) – analysis of the Solar Wind magnetic field and electron density using PPTA observations of J1022+1001 • Manchester et al. (2010) – relativistic spin precession in PSR J1141-6545 • Weltevrede et al. (2010) – Pulsar timing for the Fermi mission • Verbiest et al. (2008) - Limits on the variation of the gravitational “constant” • You et al. (2007) - Studies of the interstellar medium • …. • - concentrate in this talk on looking for correlations between timing residuals …. CSIRO. Gravitational wave detection
Developing a pulsar-based time standardParkes data + Arecibo Best time standard w.r.t. TT(TAI) Pulsar time standard w.r.t TT(TAI) CSIRO. Gravitational wave detection
Measuring planetary masses • Use International Pulsar Timing Array data from Parkes, Effelsberg, Nancay and Arecibo. • Champion et al. 2010, ApJ. • A planetary mass error will lead to incorrect determination of the Solar System barycentre => correlated pulsar timing residuals • Can fit to multiple pulsars simultaneously to search for such a signal CSIRO. Gravitational wave detection
Measuring planetary mass • Champion, Hobbs, Manchester et al. (2010), ApJ, 720, 201 • Use data from Parkes, Arecibo, Effelsberg and Nancay 9.54791915(11)x10-4 CSIRO. Gravitational wave detection
Published limits on gravitational wave background (95% confidence) All use the same Kaspi et al. (1994) data set Poor choice of pulsar? Tentative new bound Incorrect algorithm? Use same data set CSIRO. Gravitational wave detection
Pulsar navigation: assume that you are on the Earth’s surface • PULSE@Parkesobservations CSIRO. Gravitational wave detection
Pulsar navigation: assume that you are on the Earth’s surface • Parkes observations CSIRO. Gravitational wave detection
Pulsar navigation: assume that you are on the Earth’s surface • Parkes observations CSIRO. Gravitational wave detection
Pulsar navigation: assume that you are on the Earth’s surface • Parkes observations CSIRO. Gravitational wave detection
Pulsar navigation: assume that you are on the Earth’s surface • Parkes observations … correct to within a few kilometres CSIRO. Gravitational wave detection
Pulsar navigation: in 3D CSIRO. Gravitational wave detection
Conclusion • Can distinguish between many phenomena by looking for correlated timing residuals between pulsars • Have improved understanding of individual pulsars • Have developed a pulsar-based time standard • Have the most precise, published, mass estimate for the Jovian system • Have not detected gravitational waves, but getting closer • Can reverse the timing procedure to determine our position. CSIRO. Gravitational wave detection