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In previous studies [1, 2, 3] the possible existence dark matter admixed pulsar have been discussed based on three different dark matter density profiles, Singular Isothermal Sphere density profile, Universal Rotational Curve density profile and Navarro-Frenk-White density profile. They have been used to discuss the pulsars present in our Milky Way galaxy as well as some satellite dwarf galaxies of Milky Way. In this article we use the Universal Rotational Curve (URC) dark matter density profile to observe similar effects on galaxies M31 and M87. These study hold significant importance, as now it can be concluded that there is a fair possibility of presence of dark matter admixed pulser in M31 and M87 galaxies as well., Comment: 17 pages, 16 figures, 2 tables

In this paper, we present a new kind of stellar model using the Nariai IV metric. This model can be used to study the strange/quark stars(which is our present interest, though it can also be applicable to neutron stars). We present a mass-radius region where all the regularity conditions, energy conditions, the TOV equation, and stability conditions are satisfied. According to our model, strange stars having mass up to $1.9165M_{\odot}(=2.81 km)$ is stable. A strange star having a mass greater than $1.9165M_{\odot}$ violates the stability conditions. This model can be very useful to predict the radius of strange stars of mass greater than $1 M_{\odot}$., Comment: 12 pages, 10 figures, 2 tables; Accepted in Astrophysics and Space Science

A new strange star model based on Durgapal IV metric (Durgapal 1982) is presented here.Here we have applied a specific method to study the inner physical properties of the compact objects 4U 1702-429, 2A 1822-371, PSR J1756-2251,PSR J1802-2124 and PSR J1713+0747.The main objective of our study is to determine central density ($\rho_{0}$), surface density ($\rho_{b}$), central pressure ($p_{0}$), surface redshift ($Z_{s}$), compactness and radius. Further we perform different tests to study the stability of our model and finally we are able to give an equation based on pressure and density i.e probable equation of state (EoS) which has an important significances in the field of Astrophysics., Comment: 8 pages,9 figures, 2 tables

We construct a relativistic model for the newly discovered millisecond pulsar PSR J0514 - 4002A located in the globular cluster NGC 1851 (A. Ridolfi, P.C.C. Freire, Y. Gupta, S.M. Ransom, MNRAS 490, 3860 (2019)) by using Tolman VII spacetime. We have obtained central density ($\rho_{0}$), central pressure ($p_{0}$), probable radius, compactness ($u$) and surface redshift ($Z_{s}$) of the above mentioned newly discovered millisecond pulsar, which is very much consistent with reported data. Equation of State (EoS) of the millisecond pulsar has comes out as stiff in nature which is physically acceptable. Not even that our proposed model can analyze most of the millisecond pulsars having masses up to $1.51 M_{\odot}$., Comment: 10 pages, 16 figures

In this paper, we have considered a twofluid model assuming that the pulsars are made of ordinary matter admixed with dark matter.Contribution of dark matter comes from the fitting of the rotation curves of the SPARC sample of galaxies[95]. For this we have investigated the dark matter based on the Singular Isothermal Sphere (SIS) dark matter density profile in the galactic halo region. Considering this twofluid model, we have studied the physical features of the pulsars present in different galaxy in details. Here, we compute the probable radii, compactness (u) and surface red-shift (Zs) of the four pulsars namely : PSR J1748-2021B in NGC 6440B galaxy, PSR J1911-5958A in NGC 6752 galaxy, PSR B1802-07 in NGC 6539 galaxy and PSR J1750-37A in NGC 6441 galaxy., Comment: 10 pages, 17 figures, Accepted in EPJ Plus

In this article, we introduce a de-sitter model in favor of compact stars in low-mass X-ray binary. Here, we merge the presence of the cosmological constant on a small scale to discussion the stellar structure and conclude that this doping is very well suitable with the familiar physical mode of the low-mass X-ray binary compact stars. We calculate the probable radii, compactness (u) and surface red-shift (Zs) of six compact stars in low-mass X-ray binaries namely Cyg X-2, V395 Carinae/2S 0921-630, XTE J2123-058, X1822-371 (V691 CrA), 4U 1820-30 and GR Mus (XB 1254-690). We also offer possible equation of state (EOS) of the stellar object., Comment: 11 pages, 15 figures; Accepted in "Research in Astronomy and Astrophysics"

The inner structure of neutron star is considered from theoretical point of view and is compared with the observed data. We have proposed a form of an equation of state relating pressure with matter density which indicates the stiff equation of state of neutron stars. From our study we have calculated mass(M), compactness(u) and surface red-shift(Zs ) for the neutron stars namely PSR J1614-2230, PSR J1903+327, Cen X-3, SMC X-1, Vela X-1, Her X-1 and compared with the recent observational data. We have also indicated the possible radii of the different stars which needs further study. Finally we have examined the stability for such type of theoretical structure., Comment: 7 pages, 11 figures and 2 tables

We present a model for compact stars in the low mass X-ray binaries(LMXBs) and X-ray pulsars using a metric given by John J. Matese and Patrick G. Whitman \citep{Matese and Whitman1980}. Here the field equations are reduced to a system of two algebraic equations considering the isotropic pressure. Compact star candidates 4U 1820-30(radius=10km) in LMXBs, and Her X-1(radius=7.7km), SAX J 1808.4-3658(SS1)(radius=7.07km) and SAX J 1808.4-3658(SS2)(radius=6.35km) in X-ray pulsars satisfy all the energy conditions, TOV-equation and stability condition. From our model, we have derived mass($M$), central density($\rho_{0}$), suface density($\rho_{b}$), central pressure($p_{0}$), surface pressure($p_{b}$) and surface red-shift($Z_{s}$) of the above mentioned stars, which are very much consistant with the observed/reported datas\citep{N. K. Glendenning1997,Gondek2000}. We have also observe the adiabatic index($\gamma$>4/3) of the above steller objects., Comment: 7 pages, 11 figures

We propose a model for compact stars in low-mass X-ray binaries(LMXBs) namely KS 1731-260, EXO 1745-248 and 4U 1608-52. Here we investigate the physical phenomena of a compact star in the LMXBs. Using our model, we have calculated central density, surface density, mass(M) and red-shift for the above mentioned compact stars, which is very much consistent with the reported data. We also obtain the possible equation of state(EOS) of the stars which is physically acceptable., Comment: 6 pages, 25 figures

In this article, we have proposed a model for a realistic strange star under Tolman VII metric\citep{Tolman1939}. Here the field equations are reduced to a system of three algebraic equations for anisotropic pressure. Mass, central density and surface density of strange star in the low-mass X-ray binary 4U 1820-30 has been matched with the observational data according to our model. Strange materials clearly satisfies the stability condition (i.e. sound velocities < 1) and TOV-equation. Here also surface red shift of the star has been found to be within reasonable limit., Comment: Some revisions have been made. Accepted in Eur.Phys.J.C

We propose a relativistic model for quintessence stars with the combination of an anisotropic pressure corresponding to normal matter and a quintessence dark energy having a characteristic parameter {\omega}q such that -1 <{\omega}q < - 1/3. We discuss various physical features of the model and show that the model satisfies all the regularity conditions and can provide stable equilibrium configurations., Comment: 6 pages, 8 figures ; Minor revisions have been made. References up dated. To appear in Astrophysics Space Science