Ritam Mallick, P. K. Sahu
Neutron stars (NS) can be made of normal hadronic matter (generally called NS) or they can have exotic states of matter in their interiors, like quark matter or color superconducting matter. Stars can have such exotic states up to their surface (called strange stars (SS)) or they can only have a quark core surrounded by hadronic matter, known as hybrid stars (HS). The hybrid stars is likely to have a mixed phase, such as both hadron and quark phases, in the intermediate region. Observational results also suggest huge surface magnetic field in certain compact stars called magnetars. The conversion of NS to SS/HS is a highly energetic process, in such conversion, the equations of state (EOS) of matter changes, resulting in the change in their masses. Special theory of relativity relates mass to energy, therefore such conversion leads to huge energy release, of the order of $10^{53}$ ergs. In this work we study the energy released by such conversion process. We also study the energy released by normal pulsars and magnetars. The final state of the star after conversion may be a SS or a HS, we have calculated the energy released for these final states. The energy released in the conversion of NS to SS is greater than the energy released in the conversion of NS to HS. We study the effect of magnetic field in the EOS. We find that if the magnetic field strength is of the order of $10^{14}$G or more, the effect in the EOS is significant and thereby the effect of the conversion process. The energy released by magnetars is found to be more than that of normal pulsars, for NS to SS conversion process, whereas for the conversion of NS to HS the energy released by magnetars is less than normal pulsars. The amount of energy released by such conversion may only be compared to the energy observed in the gamma ray bursts (GRB).
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http://arxiv.org/abs/1208.2499
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