Not all pulsars pulse regularly. Since the connection between pulsar radio emission and timing properties in the so-called intermittent pulsars was first pointed out [27] more pulsars exhibiting these properties have been discovered, as well as, e.g., multi-wavelength moding pulsars where the pulse profile changes significantly between two states having different radio and X-ray properties [28]. Secular variations in previously thought stable pulse profiles were also seen for a large sample of ordinary pulsars [29] with a clear connection between timing irregularities/noise and emission properties/profiles. In this context, progress is being made on understanding pulsar interiors and how/if the observed pulse profile variations could be ascribed to long term free precession. Finally, the LOFAR telescope is revealing the complex imprints of the ISM on pulsar data [30]. The Thousand Pulsar Timing Array will provide an opportunity to study the breadth of pulsar phenomenology. That will result in new breakthroughs relating to the interiors, to the magnetosphere and to the environment of pulsars, to ISM and Galactic magnetic field studies, and will lead to improved pulsar timing. MeerKAT is an exceptionally sensitive telescope for this purpose. We estimate that, with the current full MeerKAT sensitivity, we can obtain a high signal to noise (>20) profile of a pulsar with a duty cycle of 5% and a flux density of 0.30 mJy (of which more than 1000 are visible from Meerkat) within a minute of observation. From a sensitivity perspective therefore, it is easy to accommodate regular observations of 1000 pulsars within the requested 16 h per observing epoch.
References:
[27] M. Kramer, A. G. Lyne, J. T. O’Brien, C. A. Jordan and D. R. Lorimer, A Periodically Active Pulsar Giving Insight into Magnetospheric Physics, Science 312, 549 (April 2006).
[28] W. Hermsen, J. W. T. Hessels, L. Kuiper, J. van Leeuwen, D. Mitra, J. de Plaa, J. M. Rankin, B. W. Stappers, G. A. E. Wright, R. Basu, A. Alexov, T. Coenen, J.-M. Grießmeier, T. E. Hassall, A. Karastergiou, E. Keane, V. I. Kondratiev, M. Kramer, M. Kuniyoshi, A. Noutsos, M. Serylak, M. Pilia, C. Sobey, P. Weltevrede, K. Zagkouris, A. Asgekar, I. M. Avruch, F. Batejat, M. E. Bell, M. R. Bell, M. J. Bentum, G. Bernardi, P. Best, L. Bîrzan, A. Bonafede, F. Breitling, J. Broderick, M. Brüggen, H. R. Butcher, B. Ciardi, S. Duscha, J. Eislöffel, H. Falcke, R. Fender, C. Ferrari, W. Frieswijk, M. A. Garrett, F. de Gasperin, E. de Geus, A. W. Gunst, G. Heald, M. Hoeft, A. Horneffer, M. Iacobelli, G. Kuper, P. Maat, G. Macario, S. Markoff, J. P. McKean, M. Mevius, J. C. A. Miller-Jones, R. Morganti, H. Munk, E. Orrú, H. Paas, M. Pandey-Pommier, V. N. Pandey, R. Pizzo, A. G. Polatidis, S. Rawlings, W. Reich, H. Röttgering, A. M. M. Scaife, A. Schoenmakers, A. Shulevski, J. Sluman, M. Steinmetz, M. Tagger, Y. Tang, C. Tasse, S. ter Veen, R. Vermeulen, R. H. van de Brink, R. J. van Weeren, R. A. M. J. Wijers, M. W. Wise, O. Wucknitz, S. Yatawatta and P. Zarka, Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere, Science 339, p. 436 (January 2013).
[29] A. Lyne, G. Hobbs, M. Kramer, I. Stairs and B. Stappers, Switched Magnetospheric Regulation of Pulsar Spin-Down, Science 329, p. 408 (July 2010).
[30] A. M. Archibald, V. I. Kondratiev, J. W. T. Hessels and D. R. Stinebring, Millisecond Pulsar Scintillation Studies with LOFAR: Initial Results, ApJL 790, p. L22 (August 2014).
References:
[27] M. Kramer, A. G. Lyne, J. T. O’Brien, C. A. Jordan and D. R. Lorimer, A Periodically Active Pulsar Giving Insight into Magnetospheric Physics, Science 312, 549 (April 2006).
[28] W. Hermsen, J. W. T. Hessels, L. Kuiper, J. van Leeuwen, D. Mitra, J. de Plaa, J. M. Rankin, B. W. Stappers, G. A. E. Wright, R. Basu, A. Alexov, T. Coenen, J.-M. Grießmeier, T. E. Hassall, A. Karastergiou, E. Keane, V. I. Kondratiev, M. Kramer, M. Kuniyoshi, A. Noutsos, M. Serylak, M. Pilia, C. Sobey, P. Weltevrede, K. Zagkouris, A. Asgekar, I. M. Avruch, F. Batejat, M. E. Bell, M. R. Bell, M. J. Bentum, G. Bernardi, P. Best, L. Bîrzan, A. Bonafede, F. Breitling, J. Broderick, M. Brüggen, H. R. Butcher, B. Ciardi, S. Duscha, J. Eislöffel, H. Falcke, R. Fender, C. Ferrari, W. Frieswijk, M. A. Garrett, F. de Gasperin, E. de Geus, A. W. Gunst, G. Heald, M. Hoeft, A. Horneffer, M. Iacobelli, G. Kuper, P. Maat, G. Macario, S. Markoff, J. P. McKean, M. Mevius, J. C. A. Miller-Jones, R. Morganti, H. Munk, E. Orrú, H. Paas, M. Pandey-Pommier, V. N. Pandey, R. Pizzo, A. G. Polatidis, S. Rawlings, W. Reich, H. Röttgering, A. M. M. Scaife, A. Schoenmakers, A. Shulevski, J. Sluman, M. Steinmetz, M. Tagger, Y. Tang, C. Tasse, S. ter Veen, R. Vermeulen, R. H. van de Brink, R. J. van Weeren, R. A. M. J. Wijers, M. W. Wise, O. Wucknitz, S. Yatawatta and P. Zarka, Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere, Science 339, p. 436 (January 2013).
[29] A. Lyne, G. Hobbs, M. Kramer, I. Stairs and B. Stappers, Switched Magnetospheric Regulation of Pulsar Spin-Down, Science 329, p. 408 (July 2010).
[30] A. M. Archibald, V. I. Kondratiev, J. W. T. Hessels and D. R. Stinebring, Millisecond Pulsar Scintillation Studies with LOFAR: Initial Results, ApJL 790, p. L22 (August 2014).