Pulsar Timing at Parkes
George Hobbs
CSIRO Australia Telescope National Facility
[email protected]
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)
CSIRO. Gravitational wave detection
Residual
A few simulations
GW background
Spin-down irregularities
Clock noise
• With one pulsar you cannot (normally) tell what unmodelled
physical effect is causing the residuals
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 standard
Parkes 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
MSun
Best Published
This work
Mercury
1.66013(7)x10-7
1.660(2)x10-7
Venus
2.4478686(4)x10-6
2.44782(10)x10-6
Mars
3.227151(9)x10-7
3.2277(8)x10-7
Jupiter*
9.547919(8)x10-4 -4
9.54791915(11)x10
2.85885670(8)x10-4
9.547916(4)x10-4
Saturn
CSIRO. Gravitational wave detection
2.858858(14)x10-4
Published limits on gravitational wave
background (95% confidence)
Poor choice of pulsar?
All use the
same
Kaspi et
al. (1994)
data set
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@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
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