Volume 627, July 2019
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||02 July 2019|
Limiting magnetic field for minimal deformation of a magnetized neutron star
Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany
2 CFisUC, University of Coimbra, 3004-516 Coimbra, Portugal
3 INESC TEC, Campus da FEUP, 4200-465 Porto, Portugal
4 Department of Physics, Kent State University, Kent, OH 44242, USA
Accepted: 30 May 2019
Aims. In this work, we study the structure of neutron stars under the effect of a poloidal magnetic field and determine the limiting largest magnetic field strength that induces a deformation such that the ratio between the polar and equatorial radii does not exceed 2%. We consider that, under these conditions, the description of magnetic neutron stars in the spherical symmetry regime is still satisfactory.
Methods. We described different compositions of stars (nucleonic, hyperonic, and hybrid) using three state-of-the-art relativistic mean field models (NL3ωρ, MBF, and CMF, respectively) for the microscopic description of matter, all in agreement with standard experimental and observational data. The structure of stars was described by the general relativistic solution of both Einstein’s field equations assuming spherical symmetry and Einstein-Maxwell’s field equations assuming an axi-symmetric deformation.
Results. We find a limiting magnetic moment on the order of 2 × 1031 Am2, which corresponds to magnetic fields on the order of 1016 G at the surface and 1017 G at the center of the star, above which the deformation due to the magnetic field is above 2%, and therefore not negligible. We show that the intensity of the magnetic field developed in the star depends on the equation of state (EoS), and, for a given baryonic mass and fixed magnetic moment, larger fields are attained with softer EoS. We also show that the appearance of exotic degrees of freedom, such as hyperons or a quark core, is disfavored in the presence of a very strong magnetic field. As a consequence, a highly magnetized nucleonic star may suffer an internal conversion due to the decay of the magnetic field, which could be accompanied by a sudden cooling of the star or a gamma ray burst.
Key words: equation of state / magnetic fields / stars: neutron
© ESO 2019
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.