Polytropic spheres with electric charge: Compact stars, the Oppenheimer-Volkoff and Buchdahl limits, and quasiblack holes

Author(s)

Arbanil, Jose D. V. ^[1] ; Lemos, Jose P. S. ^[2] ; Zanchin, Vilson T. ^[1]

Affiliation

^[1] Univ Fed ABC, Ctr Ciencias Nat & Humanas, BR-09210170 Sao Paulo - Brazil

^[2] Univ Lisbon, Inst Super Tecn, Ctr Multidisciplinar Astrofis CENTRA, Dept Fis, P-1049001 Lisbon - Portugal

• Document type: Journal article
• Source: Physical Review D; v. 88, n. 8 OCT 16 2013.
• Web of Science Citations: 23

Abstract

We explore a class of compact charged spheres made of a charged perfect fluid with a polytropic equation of state. The charge density is chosen to be proportional to the energy density. The study is performed by solving the Tolman-Oppenheimer-Volkoff equation, which describes the hydrostatic equilibrium. We show the dependence of the structure of the spheres for several characteristic values of the polytropic exponent and for different values of the charge densities. We also study other physical properties of the charged spheres, such as the total mass, total charge, radius and sound speed and their dependence on the polytropic exponent. We find that for the polytropic exponent gamma = 4/3 the Chandrasekhar mass limit coincides with the Oppenheimer-Volkoff mass limit. We test the Oppenheimer-Volkoff limit for such compact objects. We also analyze the Buchdahl limit for these charged polytropic spheres, which happens in the limit of very high polytropic exponents, i.e., for a stiff equation of state. It is found that this limit is extremal and it is a quasiblack hole. (AU)

• FAPESP's process: 12/08041-5 - Regular black holes, quasiblack holes and other compact objects in general relativity
• Grantee: Vilson Tonin Zanchin
• Support Opportunities: Scholarships abroad - Research