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A radio pulsar with an 8.5-second period that challenges emission models


Radio pulsars are rotating neutron stars that emit beams of radiowaves from regions above their magnetic poles. Popular theories1,2,3,4 of the emission mechanism require continuous electron–positron pair production, with the potential responsible for accelerating the particles being inversely related to the spin period. Pair production will stop when the potential drops below a threshold, so the models predict that radio emission will cease when the period exceeds a value that depends on the magnetic field strength and configuration. Here we show that the pulsar J2144−3933, previously thought to have a period of 2.84 s, actually has a period of 8.51 s, which is by far the longest of any known radio pulsar. Moreover, under the usual model assumptions5, based on the neutron-star equations of state, this slowly rotating pulsar should not be emitting a radio beam. Therefore either the model assumptions are wrong, or current theories of radio emission must be revised.

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Figure 1: Pulse profile for PSR J2144−3933 at 436 MHz when folded with the correct period of 851 s.
Figure 2: Distribution of known pulsars (excluding globular cluster pulsars) on the PBs plane, where P is the pulsar period and Bs is the surface magnetic dipole field strength.

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  1. Ruderman, M. A. & Sutherland, P. G. Theory of pulsars: Polar gaps, sparks, and coherent microwave radiation. Astrophys. J. 196, 51–72 (1975).

    Article  ADS  CAS  Google Scholar 

  2. Machabeli, G. Z. & Usov, V. V. Cyclotron instability in the magnetosphere of the Crab Nebula pulsar, and the origin of its radiation. Sov. Astron. Lett. 5, 238–241 (1979).

    ADS  Google Scholar 

  3. Cheng, A. F. & Ruderman, M. A. Particle acceleration and radio emission above pulsar polar caps. Astrophys. J. 235, 576–586 (1980).

    Article  ADS  CAS  Google Scholar 

  4. Beskin, V. S., Gurevich, A. V. & Istomin, Y. N. Theory of the radio emission of pulsars. Astrophys. Space Sci. 146, 205–281 (1988).

    Article  ADS  CAS  Google Scholar 

  5. Manchester, R. N. & Taylor, J. H. Pulsars (Freeman, San Francisco, 1977).

    Google Scholar 

  6. Manchester, R. N. et al. The Parkes Southern Pulsar Survey — I. Observing and data analysis systems and initial results. Mon. Not. R. Astron. Soc. 279, 1235–1250 (1996).

    Article  ADS  Google Scholar 

  7. Lyne, A. G. et al. The Parkes Southern Pulsar Survey — II. Final results and population analysis. Mon. Not. R. Astron. Soc. 295, 743–755 (1998).

    Article  ADS  Google Scholar 

  8. D'Amico, N. et al. The Parkes Southern Pulsar Survey — III. Timing of long-period pulsars. Mon. Not. R. Astron. Soc. 297, 28–40 (1998).

    Article  ADS  Google Scholar 

  9. Johnston, S., Nicastro, L. & Koribalski, B. Scintillation parameters for 49 pulsars. Mon. Not. R. Astron. Soc. 297, 108–116 (1998).

    Article  ADS  Google Scholar 

  10. Camilo, F. & Nice, D. J. Timing parameters of 29 pulsars. Astrophys. J. 445, 756–761 (1995).

    Article  ADS  Google Scholar 

  11. Lyne, A. G. & Manchester, R. N. The shape of pulsar radio beams. Mon. Not. R. Astron. Soc. 234, 477–508 (1988).

    Article  ADS  Google Scholar 

  12. Rankin, J. M. Toward an empirical theory of pulsar emission. IV. Geometry of the core emission region. Astrophys. J. 352, 247–257 (1990).

    Article  ADS  Google Scholar 

  13. Rankin, J. M. Toward an empirical theory of pulsar emission. I. Morphological taxonomy. Astrophys. J. 274, 333–358 (1983).

    Article  ADS  Google Scholar 

  14. Manchester, R. N., Han, J. L. & Qiao, G. J. Polarization observations of 66 southern pulsars. Mon. Not. R. Astron. Soc. 295, 280–298 (1998).

    Article  ADS  Google Scholar 

  15. van Paradijs, J., Taam, R. E. & van den Heuvel, E. P. J. On the nature of the ‘anomalous’ 6-s X-ray pulsars. Astron. Astrophys. 299, L41–L44 (1995).

    ADS  CAS  Google Scholar 

  16. Kouveliotou, C. et al. An X-ray pulsar with a superstrong magnetic field in the soft γ-ray repeater SGR1806-20. Nature 393, 235–237 (1998).

    Article  ADS  CAS  Google Scholar 

  17. Duncan, R. C. & Thompson, C. Formation of very strongly magnetized neutron stars: Implications for gamma-ray bursts. Astrophys. J. 392, L9–L13 (1992).

    Article  ADS  CAS  Google Scholar 

  18. Baring, M. G. & Harding, A. K. Radio-quiet pulsars with ultra-strong magnetic fields. Astrophys. J. 507, L55–L58 (1998).

    Article  ADS  Google Scholar 

  19. Chen, K. & Ruderman, M. Pulsar death lines and death valley. Astrophys. J. 402, 264–270 (1993).

    Article  ADS  Google Scholar 

  20. Weatherall, J. C. & Eilek, J. A. Are there two pulsar emission mechanisms? Astrophys. J. 474, 407–413 (1997).

    Article  ADS  Google Scholar 

  21. Taylor, J. H. & Cordes, J. M. Pulsar distances and the Galactic distribution of free electrons. Astrophys. J. 411, 674–684 (1993).

    Article  ADS  Google Scholar 

  22. Lyne, A. G., Manchester, R. N. & Taylor, J. H. The Galactic population of pulsars. Mon. Not. R. Astron. Soc. 213, 613–639 (1985).

    Article  ADS  Google Scholar 

  23. Lorimer, D. R., Bailes, M., Dewey, R. J. & Harrison, P. A. Pulsar statistics: The birthrate and initial spin periods of radio pulsars. Mon. Not. R. Astron. Soc. 263, 403–415 (1993).

    Article  ADS  Google Scholar 

  24. Tauris, T. M. & Manchester, R. N. On the evolution of pulsar beams. Mon. Not. R. Astron. Soc. 298, 625–636 (1998).

    Article  ADS  Google Scholar 

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M.D.Y. thanks R. Burman for comments on this manuscript, and R. Burman and B.Kenny for advice. M.D.Y. also thanks the University of Western Australia for partial financial support. The Parkes radio telescope is part of the Australia Telescope, which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.

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Correspondence to M. D. Young.

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Young, M., Manchester, R. & Johnston, S. A radio pulsar with an 8.5-second period that challenges emission models. Nature 400, 848–849 (1999).

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