Magnetic collapse of a neutron gas: Can magnetars indeed be formed?A. Pérez Martínez1, H. Pérez Rojas1, 2, 3 and H. J. Mosquera Cuesta3, 4
1 Grupo de Física Teórica, ICIMAF, Calle E No. 309, 10400 La Habana, Cuba
2 High Energy Physics Division, Department of Physics, University of Helsinki and Helsinki Institute of Physics, P.O. Box 64, 00014 Helsinki, Finland
3 Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, Strada Costiera 11, Miramare 34100, Trieste, Italy
4 Centro Brasileiro de Pesquisas Físicas, Laboratório de Cosmologia e Física Experimental de Altas Energias, Rua Dr. Xavier Sigaud 150, CEP 22290-180, Urca, Rio de Janeiro, RJ, Brazil
(Received: 25 November 2002 / Revised version: 25 February 2003 / Published online: 5 May 2003)
A relativistic degenerate neutron gas in equilibrium with a background of electrons and protons in a magnetic field exerts its pressure anisotropically, having a smaller value perpendicular to than along the magnetic field. For critical fields the magnetic pressure may produce the vanishing of the equatorial pressure of the neutron gas. Taking this as a model for neutron stars, the outcome could be a transverse collapse of the star. This fixes a limit to the fields to be observable in stable neutron star pulsars as a function of their density. The final structure left over after the implosion might be a mixed phase of nucleons and a meson condensate, a strange star, or a highly distorted black hole or black "cigar", but not a magnetar, if viewed as a superstrongly magnetized neutron star. However, we do not exclude the possibility of superstrong magnetic fields arising in supernova explosions which lead directly to strange stars. In other words, if any magnetars exist, they cannot be neutron stars.
© Società Italiana di Fisica, Springer-Verlag 2003