Charged analogues of Schwarzschild interior solution in terms of pressure

Recently, Bijalwan (Astrophys. Space Sci., doi: 10.1007/s10509-011-0691-0, 2011a) discussed charged fluid spheres with pressure while Bijalwan and Gupta (Astrophys. Space Sci. 317, 251-260, 2008) suggested using a monotonically decreasing function f to generate all possible physically viable charged analogues of Schwarzschild interior solutions analytically. They discussed some previously known and new solutions for Schwarzschild parameter u(= GM/c(2)a) <= 0.142, a being radius of star. In this paper we investigate wide range of u by generating a class of solutions that are well behaved and suitable for modeling Neutron star charge matter. We have exploited the range u = 0.142 by considering pressure p = p(omega) and f = (f(0)(1 - R(2)(1-omega)/a(2)) + f(a) R(2)(1-omega)/a(2)), where omega = 1 -r(2)/R(2) to explore new class of solutions. Hence, class of charged analogues of Schwarzschild interior is found for barotropic equation of state relating the radial pressure to the energy density. The analytical models thus found are well behaved with surface red shift z(s) <= 0.181, central red shift z(c) <= 0.282, mass to radius ratio M/a <= 0.149, total charge to total mass ratio e/M = 0.807 and satisfy Andreasson's (Commun. Math. Phys. 288, 715-730, 2009) stability condition. Red-shift, velocity of sound and p/c(2)rho are monotonically decreasing towards the surface while adiabatic index is monotonically increasing. The maximum mass found to be 1.512 M(Theta) with linear dimension 14.964 km. Class of charged analogues of Schwarzschild interior discussed in this paper doesn't have neutral counter part. These solutions completely describe interior of a stable Neutron star charge matter since at centre the charge distribution is zero, e/M = 0.807 and a typical neutral Neutron star has mass between 1.35 and about 2.1 solar mass, with a corresponding radius of about 12 km (Kiziltan et al., arXiv: 1011.4291 [astro-ph. GA], 2010).