RADIO PHYSICS AND RADIO ASTRONOMY

PACS numbers: 97.60.Gb, 97.60.Jd, 95.30.Lz

The stationary axisymmetric force-free magnetosphere of a pulsar is considered by accounting for the polar gap and current circuit. Adjustment of the vacuum polar gap and the closing current sheet with the force-free magnetosphere of a monopolar structure is studied. For the transition layer between the vacuum and force-free regions, the self-consistent distributions of fields, currents and charges are analyzed, as well as the force and energetic balance examined. As is shown, in the case considered the transition layer characteristic scale is no less than the polar gap altitude, whereas the current closure is dissipation-free. The consequences of the results obtained for the interpretation of pulsar emission are discussed. In particular, the correlation between the radio and X-ray emission modes in the pulsar PSR B0943+10 is explained.

Key words: neutron star, pulsar, force-free magnetosphere, polar gap, pulsar current circuit

Manuscript submitted 09.11.2015

Radio phys. radio astron. 2015, 20(4): 275-285

REFERENCES

1. HARDING, A. K., TADEMARU, E. and ESPOSITO, L. W., 1978. Acurvature-radiation-pair-production model for gamma-ray pulsars. Astrophys. J. vol. 225, pp. 226-236. DOI: https://doi.org/10.1086/156486

2. DAUGHERTY, J. K. and HARDING, A. K., 1982. Electromagnetic cascades in pulsars. Astrophys. J. vol. 252, pp. 337–347. DOI: https://doi.org/10.1086/159561

3. DAUGHERTY, J. K. and HARDING, A. K., 1996. Gamma-Ray Pulsars: Emission from Extended Polar CAP Cascades. Astrophys. J. vol. 458, pp. 278–292. DOI: https://doi.org/10.1086/176811

4. ARONS, J. and SCHARLEMANN, E. T., 1979. Pair formation above pulsar polar caps – Structure of the low altitude acceleration zone. Astrophys. J. vol. 231, pp. 854–879. DOI: https://doi.org/10.1086/157250

5. ARONS, J., 1983. Pair creation above pulsar polar caps – Geometrical structure and energetics of slot gaps. Astrophys. J. vol. 266, pp. 215–241. DOI: https://doi.org/10.1086/160771

6. MUSLIMOV, A. G. and HARDING, A. K., 2003. Extended Acceleration in Slot Gaps and Pulsar High-Energy Emission. Astrophys. J. vol. 588, no, 1, pp. 430–440. DOI: https://doi.org/10.1086/368162

7. MUSLIMOV, A. G. and HARDING, A. K., 2004. High-Altitude Particle Acceleration and Radiation in Pulsar Slot Gaps. Astrophys. J. vol. 606, no. 2, pp. 1143–1153. DOI: https://doi.org/10.1086/383079

8. DYKS, J. and RUDAK, B., 2003. Two-Pole Caustic Model for High-Energy Light Curves of Pulsars. Astrophys. J. vol. 598, no. 2, pp. 1201–1206. DOI: https://doi.org/10.1086/379052

9. DYKS, J., HARDING, A. K. and RUDAK, B., 2004. Relativistic Effects and Polarization in Three High-Energy Pulsar Models. Astrophys. J. vol. 606, no. 2, pp. 1125–1142. DOI: https://doi.org/10.1086/383121

10. CHENG, K. S., HO, C. and RUDERMAN, M., 1986. Energetic radiation from rapidly spinning pulsars. I - Outer magnetosphere gaps. Astrophys. J. vol. 300, pp. 500–521. DOI: https://doi.org/10.1086/163829

11. CHENG, K. S., HO, C. and RUDERMAN, M., 1986. Energetic Radiation from Rapidly Spinning Pulsars. II. VELA and Crab. Astrophys. J. vol. 300, pp. 522–539. DOI: https://doi.org/10.1086/163830

12. ROMANI, R. W. and YADIGAROGLU, I.-A., 1995. Gamma-ray pulsars: Emission zones and viewing geometries. Astrophys. J. vol. 438, pp. 314–321. DOI: https://doi.org/10.1086/175076

13. CHENG, K. S., RUDERMAN, M. and ZHANG, L., 2000. AThree-dimensional Outer Magnetospheric Gap Model for Gamma-Ray Pulsars: Geometry, Pair Production, Emission Morphologies, and Phase-resolved Spectra. Astrophys. J. vol. 537, no. 2, pp. 964–976. DOI: https://doi.org/10.1086/309051

14. MICHEL, F. C., 1973. Rotating Magnetospheres: an Exact 3-D Solution. Astrophys. J. vol. 180, pp. L133–L136. DOI: https://doi.org/10.1086/181169

15. SCHARLEMANN, E. T. and WAGONER, R. V., 1973. Aligned Rotating Magnetospheres. General Analysis. Astrophys. J. vol. 182, pp. 951–960. DOI: https://doi.org/10.1086/152195

16. OKAMOTO, I., 1974. Force-free pulsar magnetosphere - I. The steady, axisymmetric theory for the charge-separa-ted plasma. Mon. Not. Roy. Astron. Soc. vol. 167, pp. 457–474.

17. PETROVA, S. A., 2013. On the Global Structure of Pulsar Force-free Magnetosphere. Astrophys. J. vol. 764, no. 2, id. 129. DOI: https://doi.org/10.1088/0004-637X/764/2/129

18. PETROVA, S. A. On the structure of pulsar axisymmetric force-free magnetosphere beyond the light cylinder. Radiofizika i Radioastronomia. vol. 18, no. 3, pp. 201–209 (in Russian).

19. CONTOPOULOS, I., KAZANAS, D. and FENDT, C., 1999. The Axisymmetric Pulsar Magnetosphere. Astrophys. J. vol. 511, no. 1, pp. 351–358. DOI: https://doi.org/10.1086/306652

20. CONTOPOULOS, I., 2005. The coughing pulsar magnetosphere. Astron. Astrophys. vol. 442, no. 2, pp. 579–586. DOI: https://doi.org/10.1051/0004-6361:20053143

21. GRUZINOV, A., 2005. Power of an Axisymmetric Pulsar. Phys. Rev. Lett. vol. 94, is. 1, id. 021101. DOI: https://doi.org/10.1103/PhysRevLett.94.021101

22. SPITKOVSKY, A., 2006. Time-dependent Force-free Pulsar Magnetospheres: Axisymmetric and Oblique Rotators. Astrophys. J. vol. 648, no. 1, pp. L51–L54. DOI: https://doi.org/10.1086/507518

23. KALAPOTHARAKOS, C. and CONTOPOULOS, I., 2009. Three-dimensional numerical simulations of the pulsar magnetosphere: preliminary results. Astron. Astrophys. vol. 496, no. 2, pp. 495–502. DOI: https://doi.org/10.1051/0004-6361:200810281

24. BAI, X.-N. and SPITKOVSKY, A., 2010. Modeling of Gamma-ray Pulsar Light Curves Using the Force-free Magnetic Field. Astrophys. J. vol. 715, no. 2, pp. 1282–1301. DOI: https://doi.org/10.1088/0004-637X/715/2/1282

25. KALAPOTHARAKOS, C., CONTOPOULOS, I. and KAZANAS, D., 2012. The extended pulsar magnetosphere. Mon. Not. Roy. Astron. Soc. vol. 420, is. 4, pp. 2793–2798. DOI: https://doi.org/10.1111/j.1365-2966.2011.19884.x

26. GRUZINOV, A., 2008. Dissipative pulsar magnetospheres. J. Cosmol. Astropart. Phys. no. 11, id. 002. DOI: https://doi.org/10.1088/1475-7516/2008/11/002

27. KALAPOTHARAKOS, C., KAZANAS, D., HARDING, A. and CONTOPOULOS, I., 2012. Toward a Realistic Pulsar Magnetosphere. Astrophys. J. vol. 749, no. 1, id. 2. DOI: https://doi.org/10.1088/0004-637X/749/1/2

28. LI, J., SPITKOVSKY, A. and TCHEKHOVSKOY, A., 2012. Resistive Solutions for Pulsar Magnetospheres. Astrophys. J. vol. 746, no. 1, id. 60. DOI: https://doi.org/10.1088/0004-637X/746/1/60

29. PARFREY, K., BELOBORODOV, A. M. and HUI, L., 2012. Introducing PHAEDRA: a new spectral code for simulations of relativistic magnetospheres. Mon. Not. Roy. Astron. Soc. vol. 423, is. 2, pp. 1416–1436. DOI: https://doi.org/10.1111/j.1365-2966.2012.20969.x

30. PETRI, J., 2012. The pulsar force-free magnetosphere linked to its striped wind: time-dependent pseudo-spectral simulations. Mon. Not. Roy. Astron. Soc. vol. 424, is. 1, pp. 605–619. DOI: https://doi.org/10.1111/j.1365-2966.2012.21238.x

31. PETROVA, S. A., 2012. Axisymmetric force-free magnetosphere of a pulsar - I. The structure close to the magnetic axis. Mon. Not. Roy. Astron. Soc. vol. 427, is. 1, pp. 514–519. DOI: https://doi.org/10.1111/j.1365-2966.2012.21961.x

32. PETROVA, S. A, 2013. Global structure of the pulsar axisymmetric force-free magnetosphere allowing for current closure on the neutron star surface. Radiofizika i Radioastronomia. vol. 18, no. 3, pp. 193–200 (in Russian).

33. RUDERMAN, M. A. and SUTHERLAND, P. G., 1975. Theory of pulsars – Polar caps, sparks, and coherent microwave radiation. Astrophys. J. vol. 196, pp. 51–72. DOI: https://doi.org/10.1086/153393

34. HERMSEN, W., HESSELS, J. W. T., KUIPER, L., VAN LEEUWEN, J., MITRA, D., DE PLAA, J., RANKIN, J. M., STAPPERS, B. W., WRIGHT, G. A. E., BASU, R., ALEXOV, A., COENEN, T., GRIEßMEIER, J.-M., HASSALL, T. E., KARASTERGIOU, A., KEANE, E., KONDRATIEV, V. I., KRAMER, M., KUNIYOSHI, M., NOUTSOS, A., SERYLAK, M., PILIA, M., SOBEY, C., WELTEVREDE, P., ZAGKOURIS, K., ASGEKAR, A., AVRUCH, I. M., BATEJAT, F., BELL, M. E., BELL, M. R., BENTUM, M. J., BERNARDI, G., BEST, P., BÎRZAN, L., BONAFEDE, A., BREITLING, F., BRODERICK, J., BRÜGGEN, M., BUTCHER, H. R., CIARDI, B., DUSCHA, S., EISLÖFFEL, J., FALCKE, H., FENDER, R., FERRARI, C., FRIESWIJK, W., GARRETT, M. A., DE GASPERIN, F., DE GEUS, E., GUNST, A. W., HEALD, G., HOEFT, M., HORNEFFER, A., IACOBELLI, M., KUPER, G., MAAT, P., MACARIO, G., MARKOFF, S., MCKEAN, J. P., MEVIUS, M., MILLER-JONES, J. C. A., MORGANTI, R., MUNK, H., ORRÚ, E., PAAS, H., PANDEY-POMMIER, M., PANDEY, V. N., PIZZO, R., POLATIDIS, A. G., RAWLINGS, S., REICH, W., RÖTTGERING, H., SCAIFE, A. M. M., SCHOENMAKERS, A., SHULEVSKI, A., SLUMAN, J., STEINMETZ, M., TAGGER, M., TANG, Y., TASSE, C., TER VEEN, S., VERMEULEN, R., VAN DE BRINK, R. H., VAN WEEREN, R. J., WIJERS, R. A. M. J., WISE, M. W., WUCKNITZ, O., YATAWATTA, S. and ZARKA, P., 2013. Synchronous X-ray and Radio Mode Switches: A Rapid Global Transformation of the Pulsar Magnetosphere. Science. vol. 339, no. 6118, pp. 436–442. DOI: https://doi.org/10.1126/science.1230960