Compact stars in binaries: investigating the composition of superdense matter
Full text  
Author(s): 
Lugones, German
;
Arbanil, Jose D. V.
Total Authors: 2

Document type:  Journal article 
Source:  Physical Review D; v. 95, n. 6 MAR 14 2017. 
Web of Science Citations:  13 
Abstract  
We study the properties of compact stars in the RandallSundrum typeII braneworld (BW) model. To this end, we solve the braneworld generalization of the stellar structure equations for a static fluid distribution with spherical symmetry considering that the spacetime outside the star is described by a Schwarzschild metric. First, the stellar structure equations are integrated employing the socalled causal limit equation of state (EOS), which is constructed using a wellestablished EOS at densities below a fiducial density, and the causalEOS P= rho above it. It is a standard procedure in general relativistic stellar structure calculations to use such EOSs for obtaining a limit in the mass radius diagram, known as the causal limit, above which no stellar configurations are possible if the EOS fulfills the condition that the sound velocity is smaller than the speed of light. We find that the equilibrium solutions in the braneworld model can violate the general relativistic causal limit, and for sufficiently large mass they approach asymptotically to the Schwarzschild limitM = 2R. Then, we investigate the properties of hadronic and strange quark stars using two typical EOSs: a nonlinear relativistic meanfield model for hadronic matter and the Massachusetts Institute of Technology (MIT) bag model for quark matter. For masses below similar to 1.5M(circle dot)2M(circle dot), the mass versus radius curves show the typical behavior found within the frame of general relativity. However, we also find a new branch of stellar configurations that can violate the general relativistic causal limit and that, in principle, may have an arbitrarily large mass. The stars belonging to this new branch are supported against collapse by the nonlocal effects of the bulk on the brane. We also show that these stars are always stable under small radial perturbations. These results support the idea that traces of extra dimensions might be found in astrophysics, specifically through the analysis of masses and radii of compact objects. (AU)  
FAPESP's process:  13/262584  Superdense matter in the universe 
Grantee:  Manuel Máximo Bastos Malheiro de Oliveira 
Support type:  Research Projects  Thematic Grants 