Model of compact star with ordinary and dark matter
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ORIGINAL ARTICLE
Model of compact star with ordinary and dark matter P. Mafa Takisa1 · L.L. Leeuw2 · S.D. Maharaj3
Received: 8 July 2020 / Accepted: 3 October 2020 © Springer Nature B.V. 2020
Abstract We study compact stars formed by dark and ordinary matter, with attributes of both neutron star matter and quark star matter. We assume an equation of state for dark matter which is consistent with the rotational curves of galaxies and for color-flavor-locked (CFL) distributions for ordinary matter. This is done in the curved Krori-Barua spacetime geometry in general relativity. We find new exact solutions of dark matter admixed compact objects, with maximum mass 2.67 M and radius around 11.16 km, with 52.40% of dark matter content. By varying the dark matter ratio, we obtain the masses of dark compact stars with masses less than 2.67 M . Keywords Einstein equations · Compact stars · Equation of state
1 Introduction A quark star is made up of self-bound strange quark matter and its also known as a hypothetical stellar object (see
B S.D. Maharaj
[email protected] P. Mafa Takisa [email protected] L.L. Leeuw [email protected]
1
Science, Engineering and Technology, School of Physics, University of South Africa, Florida Science Campus, P O Box 392, Unisa 0003, South Africa
2
Department of Physics and Astronomy, University of the Western Cape, Bellville 7535, South Africa
3
Astrophysics Research Centre, School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
Witten (1984), Itoh (1970), Farhi and Jaffe (1984), Weber (2005), Ivanenko and Kurdgelaidze (1965) and Mukhopadhyay and Schaffner-Bielich (2016)). The equation of state for quark stars is not well understood which leads to controversies. The most known equation of state for compact stars composed of quark matter is the MIT bag model (Chodos et al. (1974)). Since Wittten’s work on quark matter (Witten (1984)) many investigations have been conducted in order to describe realistic physical features of these stellar compact objects. For more details see Haensel et al. (1986), Alcock et al. (1986), Benvenuto and Horvath (1989), Lugones and Horvath (2002, 2003), Alford et al. (2005), Bodmer (1971), Terazawa et al. (1978) and Rocha et al. (2019). The discovery of new observed pulsars with mass above 1.97 M challenges the theoretical approach in describing compact stars. Some studies have suggested that these compact stars might be made up of stable dark matter with non-annihilating particles. The underlying assumption is that dark matter particles can accumulate inside the stellar core of the object (Ciarcellut and Sandin (2011)). From observations at galactic scales, the proof of dark matter presence with a large fraction of matter in our universe is an inevitable fact. Based on the above mentioned statement, it is believed that some dark matter could accumulate inside the stellar structure. This process could take place at the stellar birth and during a star’s lifetime (Sandin and
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