What’s the deal with PSR J1022+1001?

Parkes Pulsar Timing Array Discussion 5 September 2012

Willem van Straten

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PSR J1022+1001 profile

PSR J1022+1001

Camilo, F., Nice, D. J., Shrauner, J. A., & Taylor, J. H. 1996, ApJ, 469, 819

•  using Arecibo and Greenbank •  first observed profile shape variations

“on a timescale of minutes” •  limit to timing precision

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PSR J1022+1001

Kramer, M., Xilouris, K. M., Camilo, F., Nice, D., Lange, C., Backer, D. C., & Doroshenko, O. 1999, ApJ, 520, 324

•  using Effelsberg •  observed profile shape variations in

both time and frequency •  EQUAD ~ 10 µs

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Xilouris, K. M. 1991, A&A, 248, 323

Result in boost ~ 0.1

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PSR J1022+1001

Ramachandran, R. & Kramer, M. 2003, A&A, 407, 1085

•  using Westerbork = equatorial mount •  therefore, no parallactic angle variation •  does not imply instrumental stability!

–  automatic gain controllers –  phase drift

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PSR J1022+1001

Hotan, A. W., Bailes, M., & Ord, S. M. 2004, MNRAS, 355, 941

•  using Parkes •  no evidence for shape variations •  timing r.m.s ~ 2.2 µs •  χ2/Nfree ~ 1.4

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Template Matching

ϕ P(φ) = aS(φ+ ϕ) + b

P(ν) = aS(ν)e-i2πϕν + δ(ν)b

FFT

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Arrival Time Comparison

•  278 TOAS spanning 6.9 years 13