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Title: Possible ambiguities in the equation of state for neutron stars

We addressed possible ambiguities on the properties of neutron stars (NSs) estimated in theoretical sides. First, roles of hyperons inside the NS are discussed through various relativistic mean field (RMF) theories. In particular, the extension of SU(6) spin-flavor symmetry to SU(3) flavor symmetry is shown to give rise to the increase of hyperon threshold density, similarly to the Fock term effects in RMF theories. As a result, about 2.0 solar mass is obtained with the hyperons. Second, the effect by the modified f(R) gravity, which leaves a room for the dark energy in the Einstein equation to be taken into account, is discussed for the NS in a strong magnetic field (MF). Our results show that the modified gravity with the Kaluza-Klein electro-magnetism theory expanded in terms of a length scale parameter may reasonably describe the NS in strong MF, so called magnetar. Even the super-soft equation of state is shown to be revived by the modified f(R) gravity.
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of)
  2. Department of Physics, Mimar Sinan Fine Arts University, Bomonti 34380, Istanbul (Turkey)
  3. Istanbul Technical University, Faculty of Science and Letters, Physics Engineering Department, Maslak 34469, Istanbul (Turkey)
  4. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan)
  5. Center for Astrophysics, Department of Physics, University of Notre Dame, IN 46556 (United States)
Publication Date:
OSTI Identifier:
22280495
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1594; Journal Issue: 1; Conference: OMEG12: 12. international symposium on origin of matter and evolution of galaxies, Tsukuba (Japan), 18-21 Nov 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; EINSTEIN FIELD EQUATIONS; EQUATIONS OF STATE; FLAVOR MODEL; GRAVITATION; HYPERONS; INTERSTELLAR MAGNETIC FIELDS; KALUZA-KLEIN THEORY; MEAN-FIELD THEORY; NEUTRON STARS; NONLUMINOUS MATTER; RELATIVISTIC RANGE; SU-3 GROUPS; SU-6 GROUPS