In MeerTime’s original 2010 science case it was anticipated that MeerKAT could independently detect a gravitational wave background after 5 years if the dimensional amplitude exceeded 2×10^−15 based upon limits in vogue at the time [9]. The current best millisecond pulsar for timing accuracy (PSR J1909–3744) already suggests that an amplitude of this magnitude is ruled out[8] and that gravitational wave detection from pulsars will require international coordination and cooperation. MeerKAT can dramatically increase the pool of MSPs from which a gravitational wave background or individual binaries can be searched for with its unique combination of sensitivity, geographical location, ability to sub-array and the speed at which it can traverse the sky. Reardon et al. (2016) [10] recently reported on the timing of 20 MSPs from Parkes and based upon his residuals and the relative sensitivity of the two telescopes, the MeerKAT should increase the number of pulsars with sub-us residuals from 5 to 16 objects if sensitivity was the only improvement factor, but MeerKAT’s ability to subarray and seek out those MSPs that are experiencing scintillation maxima gives us hope that it can do much better than a simple scaling of sensitivities might suggest. Several studies [11,12,13,14] have demonstrated that pulsar timing precision is ultimately limited by the stochastic wideband impulse-modulated self-noise (SWIMS, also known as jitter and single-pulse variability) that is intrinsic to the pulsar emission. Consequently, optimal use of full array sensitivity requires the ability to divide it into sub-arrays; furthermore, because it is imperative to account for this noise in high-precision pulsar timing data analysis, the instrumentation for pulsar timing must be updated to produce additional statistical information. It has been demonstrated[12,13] that arrival time estimation bias can be mitigated by measuring the periodic correlations of the Stokes parameters and Shannon et al. (2014) [14] have described how jitter noise can be characterised and incorporated in estimates of arrival time precision. Ongoing research by our team will combine these approaches using generalised least squares estimation to simultaneously reduce bias, accurately estimate uncertainty, and increase the sensitivity of experiments such as pulsar timing arrays. Gravitational waves are just one of the exciting science cases to be realised by timing an array of millisecond pulsars. Timing residuals also contain a wealth of information about the parameters of the parent binary, useful for studies of stellar evolution, the IGM and even our own planetary ephemerides. Since our original proposal the Fermi satellite has unveiled a tremendous population of millisecond pulsars (now up to 350) waiting for an instrument capable of producing accurate arrival times to capitalise on them. MeerKAT is such an instrument.
References:
[8] R. M. Shannon, V. Ravi, L. T. Lentati, P. D. Lasky, G. Hobbs, M. Kerr, R. N. Manchester, W. A. Coles, Y. Levin, M. Bailes, N. D. R. Bhat, S. Burke-Spolaor, S. Dai, M. J. Keith, S. Osłowski, D. J. Reardon, W. van Straten, L. Toomey, J.-B. Wang, L. Wen, J. S. B. Wyithe and X.-J. Zhu, Gravitational waves from binary supermassive black holes missing in pulsar observations, Science 349, 1522 (September 2015).
[9] J. P. W. Verbiest, M. Bailes, W. A. Coles, G. B. Hobbs, W. van Straten, D. J. Champion, F. A. Jenet, R. N. Manchester, N. D. R. Bhat, J. M. Sarkissian, D. Yardley, S. Burke-Spolaor, A. W. Hotan and X. P. You, Timing stability of millisecond pulsars and prospects for gravitational-wave detection, MNRAS 400, 951 (December 2009).
[10] D. J. Reardon, G. Hobbs, W. Coles, Y. Levin, M. J. Keith, M. Bailes, N. D. R. Bhat, S. Burke-Spolaor, S. Dai, M. Kerr, P. D. Lasky, R. N. Manchester, S. Osłowski, V. Ravi, R. M. Shannon, W. van Straten, L. Toomey, J. Wang, L. Wen, X. P. You and X.-J. Zhu, Timing analysis for 20 millisecond pulsars in the Parkes Pulsar Timing Array, MNRAS 455, 1751 (January 2016).
[11] K. Liu, J. P. W. Verbiest, M. Kramer, B. W. Stappers, W. van Straten and J. M. Cordes, Prospects for high-precision pulsar timing, MNRAS 417, 2916 (November 2011).
[12] S. Osłowski, W. van Straten, G. B. Hobbs, M. Bailes and P. Demorest, High signal-to-noise ratio observations and the ultimate limits of precision pulsar timing, MNRAS 418, 1258 (December 2011).
[13] S. Osłowski, W. van Straten, P. Demorest and M. Bailes, Improving the precision of pulsar timing through polarization statistics, MNRAS 430, 416 (March 2013).
[14] R. M. Shannon, S. Osłowski, S. Dai, M. Bailes, G. Hobbs, R. N. Manchester, W. van Straten, C. A. Raithel, V. Ravi, L. Toomey, N. D. R. Bhat, S. Burke-Spolaor, W. A. Coles, M. J. Keith, M. Kerr, Y. Levin, J. M. Sarkissian, J.-B. Wang, L. Wen and X.-J. Zhu, Limitations in timing precision due to single-pulse shape variability in millisecond pulsars, MNRAS 443, 1463 (September 2014).
References:
[8] R. M. Shannon, V. Ravi, L. T. Lentati, P. D. Lasky, G. Hobbs, M. Kerr, R. N. Manchester, W. A. Coles, Y. Levin, M. Bailes, N. D. R. Bhat, S. Burke-Spolaor, S. Dai, M. J. Keith, S. Osłowski, D. J. Reardon, W. van Straten, L. Toomey, J.-B. Wang, L. Wen, J. S. B. Wyithe and X.-J. Zhu, Gravitational waves from binary supermassive black holes missing in pulsar observations, Science 349, 1522 (September 2015).
[9] J. P. W. Verbiest, M. Bailes, W. A. Coles, G. B. Hobbs, W. van Straten, D. J. Champion, F. A. Jenet, R. N. Manchester, N. D. R. Bhat, J. M. Sarkissian, D. Yardley, S. Burke-Spolaor, A. W. Hotan and X. P. You, Timing stability of millisecond pulsars and prospects for gravitational-wave detection, MNRAS 400, 951 (December 2009).
[10] D. J. Reardon, G. Hobbs, W. Coles, Y. Levin, M. J. Keith, M. Bailes, N. D. R. Bhat, S. Burke-Spolaor, S. Dai, M. Kerr, P. D. Lasky, R. N. Manchester, S. Osłowski, V. Ravi, R. M. Shannon, W. van Straten, L. Toomey, J. Wang, L. Wen, X. P. You and X.-J. Zhu, Timing analysis for 20 millisecond pulsars in the Parkes Pulsar Timing Array, MNRAS 455, 1751 (January 2016).
[11] K. Liu, J. P. W. Verbiest, M. Kramer, B. W. Stappers, W. van Straten and J. M. Cordes, Prospects for high-precision pulsar timing, MNRAS 417, 2916 (November 2011).
[12] S. Osłowski, W. van Straten, G. B. Hobbs, M. Bailes and P. Demorest, High signal-to-noise ratio observations and the ultimate limits of precision pulsar timing, MNRAS 418, 1258 (December 2011).
[13] S. Osłowski, W. van Straten, P. Demorest and M. Bailes, Improving the precision of pulsar timing through polarization statistics, MNRAS 430, 416 (March 2013).
[14] R. M. Shannon, S. Osłowski, S. Dai, M. Bailes, G. Hobbs, R. N. Manchester, W. van Straten, C. A. Raithel, V. Ravi, L. Toomey, N. D. R. Bhat, S. Burke-Spolaor, W. A. Coles, M. J. Keith, M. Kerr, Y. Levin, J. M. Sarkissian, J.-B. Wang, L. Wen and X.-J. Zhu, Limitations in timing precision due to single-pulse shape variability in millisecond pulsars, MNRAS 443, 1463 (September 2014).