Twin Neutron Stars considering Hyperons

Document Type : Full length research Paper

Authors

1 Department of Physics, University of Zanjan, Zanjan, Iran

2 Department of Physics, Faculty of Science, University of Zanjan, Zanjan, Iran

Abstract

In this paper, we assume that the core of the neutron star consists of nucleons, leptons, and hyperons. We investigate the equation of state of neutron star matter using the LOCV method with AV18 potential,, TNI and also excluded volume effect (VE). We obtain the mass-radius relation of twin neutron stars in the presence of hyperons. The obtained results demonstrate that the threshold density of sigma hyperon lies in the range of (0.243-0.552) fm^-3 and that of lambda hyperon exists in the range of (0.353-0.940) fm^-3 . It is obvious that the appearance of hyperons softens the equation of state of neutron star matter, which is largely compensated by considering the radius for nucleons. The comparison of the results obtained for the mass-radius relation of neutron stars shows that the presence of hyperons using potential reduces the maximum mass of neutron stars from 2.11 to 1.12 M_sun . However, this parameter reaches the value of 1.5 M_sun by including the VE which indicates stiffening of the equation of state. In addition, excluded volume effect leads to instability after the appearance of hyperons, which implies the existence of a twin neutron star, two stars of the same mass but different radii.

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References

[1] J.E. Christian, A. Zacchi, J. Schaffner-Bielich, Signals in the tidal deformability for phase transitions in compact stars with constraints from GW170817‏, Physical Review D 99 (2019) 023009. https://doi.org/10.1103/PhysRevD.99.023009
[2] B. Kämpfer, On the possibility of stable quark and pion-condensed stars‏, Journal of Physics A:Mathematical and General 14 (1981) L471. https://doi.org/10.1088/0305-4470/14/11/009
[3] N.K. Glendenning, C. Kettner, Possible third family of compact stars more dense than neutron stars,‏ Astronomy and Astrophys 353 (2000) L9.
[4] J. Schaffner-Bielich, M. Hanauske, H. Stoecker, W. Greiner, Phase transition to hyperon matter in neutron stars, Physical. Review Letters 89 (2002) 171101. https://doi.org/10.1103/PhysRevLett.89.171101
[5] J. Zdunik, P. Haensel, Maximum mass of neutron stars and strange neutron-star cores‏, Astronomy and Astrophysics 551 (2013) A61. https://doi.org/10.1051/0004-6361/201220697
[6] M.G. Alford, G.F. Burgio, S. Han, G. Taranto, D. Zappala, Constraining and applying a generic high-density equation of state‏, Physical Review D 92 (2015) 083002. https://doi.org/10.1103/PhysRevD.92.083002
[7] J.-E. Christian, A. Zacchi, and J. Schaffner-Bielich, Classifications of twin star solutions for a constant speed of sound parameterized equation of state, European Physical Journal A 54 (2018) 28.  https://doi.org/10.1140/epja/i2018-12472-y
[8] S. Khanmohamadi, H.R. Moshfegh, S.A. Tehrani, Hybrid star within the framework of a lowest-order constraint variational method, Physical Review D 101 (2020) 023004. https://doi.org/10.1103/PhysRevD.101.023004
[9] Z. Sharifi, M. Bigdeli, and D. Alvarez-Castillo, Studying VLOCV twin compact stars with binary mergers, Physical Review D 103 (2021) 103011. https://doi.org/10.1103/PhysRevD.103.103011
[10] I. Vidana, A. Polls, A. Ramos, Hyperon-hyperon interactions and properties of neutron star matter, Physical Review C 62 (2000) 035801.    https://doi.org/10.1103/PhysRevC.62.035801
[11] I. Vidana, D. Logoteta, C. Providencia, A. Poll, I. Bombaci, An analytic parametrization of the hyperonic matter equation of state, arXiv:1004.3958 (2010). https://arxiv.org/abs/1004.3958
[12] V.A. Ambartsumyan, G.S. Saakyan, The degenerate superdense gas of elementary particles, Soviet Astronomy 4 (1960) 187.
[13] H. Dapo, B.J. Schaefer, J. Wambach, Appearance of hyperons in neutron stars, Physical Review C 81 (2010) 035803. https://doi.org/10.1103/PhysRevC.81.035803
[14] M. Shahrbaf, H.R. Moshfegh, Appearance of hyperons in neutron stars within LOCV method, Annals of Physics 402 (2019) 66. https://doi.org/10.1016/j.aop.2019.01.008
[15] P. Yue, F. Yang, H. Shen, Properties of hyperonic matter in strong magnetic fields, Physical Review C 79 (2009) 025803. https://doi.org/10.1103/PhysRevC.79.025803
[16] R.B. Wiringa, V.G.J. Stoks, R. Schiavilla, Accurat nucleon-nucleon potential with charge-independence breaking, Physical Review C 51 (1995) 38. https://doi.org/10.1103/PhysRevC.51.38
[17] I.E. Lagaris, V.R. Pandharipande, Variational calculations of realistic models of nuclear matter, Nuclear Physics A359 (1981) 349. https://doi.org/10.1016/0375-9474(81)90241-4
[18] J.W. Clark, N.-C. Chao, Effect of attractive nuclear forces on the onset of ferromagnetism in neutron star matter, Lettere al Nuovo Cimento 2 (1969) 185-188.
[19] J.C. Owen, R.F. Bishop, J.M. Irvine, A variational approach to nuclear matter with realistic potentials, Nuclear Physics A277 (1977) 45.      https://doi.org/10.1016/0375-9474(77)90261-5
[20] M. Bigdeli, Ferromagnetic and antiferromagnetic spin-ordering stabilities of asymmetric nuclear matter: Lowest-order constrained variational method, Physical Review C 82 (2010) 054312. https://doi.org/10.1103/PhysRevC.82.054312
[21] G.H. Bordbar, M. Modarres, Lowest order constrained variational calculation for asymmetrical nuclear matter with the new Argonne potential, Physical Review C 57 (1998) 714.      https://doi.org/10.1103/PhysRevC.57.714
[22] G.F. Burgio, M. Baldo, O.E. Nicotra, H.J. Schulze, A microscopic equation of state for protoneutron stars, Astrophysics and Space Science 308 (2007) 387-394. https://doi.org/10.1007/s10509-007-9360-8
[23] R.C. Tolman, Static solutions of Einstein’s field equations for spheres of fluid, Physical Review 55 (1939) 364. https://doi.org/10.1103/PhysRev.55.364
[24] J. Oppenheimer, G. Volkoff, On massive neutron cores, Physical Review 55 (1939) 374. https://doi.org/10.1103/PhysRev.55.374
[25] Z.A. Aghbolaghi, M. Bigdeli, Argonne family potentials and neutron star matter equation of state‏, The European Physical Journal Plus 134 (2019) 430. https://doi.org/10.1140/epjp/i2019-12843-3
[26] L. Rezzolla, E.R. Most Elias, R. Weih Lukas, Using gravitational-wave observations and quasi-universal relations to constrain the maximum mass of neutron stars‏, The Astrophysical Journal Letters 852 (2018) L25. https://doi.org/10.3847/2041-8213/aaa401

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History

  • Receive Date: 06 April 2021
  • Revise Date: 04 July 2021
  • Accept Date: 08 November 2021

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