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Claudio M. G. de Sousa

Publications and source records attributed to Claudio M. G. de Sousa.

6 recordsLinked to original sources
arXiv2011

A Polytropic Approach to Semi-relativistic Isothermal Gas Spheres at Arbitrary Temperature

We use standard polynomial expansion technique to show the existence of a relation between polytropic model and the description of gas spheres at finite temperature. A numerical analysis is made concerning the obtained perturbative parameters. It is shown that there is a correspondence between polytropic and gas sphere thermal models for fermions and bosons. For instance, the polytropic index $n$ displays evident correlation with temperature and chemical potential.

astro-ph.CO↗
arXiv2010

On the frequency shift of gravitational waves

Considering plane gravitational waves propagating through flat spacetime, it is shown that curvatures experienced both in the starting point and during their arrival at the earth can cause a considerable shift in the frequencies as measured by earth and space-based detectors. Particularly for the case of resonant bar detectors this shift can cause noise-filters to smother the signal.

gr-qc↗
arXiv2006

Rotating Boson and Boson-Fermion Stars

Some recent results on rotating self-gravitating configurations composed with Bosons and Fermions are reported. Given a star composed of both Bosons and Fermions without interaction, it is shown that it is possible to obtain stable slowly rotating configurations by using the same perturbative relativistic method that usually describes neutron stars.

astro-ph↗
arXiv1995

Boson Star Rotation: A Newtonian Approximation

Using the Newtonian approximation, we study rotating compact bosonic objects. The equations which describe stationary states with non-zero angular momentum are constructed and some numerical results are presented as examples. Limits on the applicability of the Newtonian approximation are discussed.

astro-ph↗
arXiv1995

A Model for Stars of Interacting Bosons and Fermions

In this paper we introduce a current-current type interaction term in the Lagrangian density of gravity coupled to complex scalar fields, in the presence of a degenerated Fermi gas. For low transferred momenta such a term, which might account for the interaction among boson and fermion constituents of compact stellar objects, is subsequently reduced to a quadratic one in the scalar sector. This procedure enforces the use of a complex radial field counterpart in the equations of motion. The real and the imaginary components of the scalar field exhibit different behaviour as the interaction increases. The results also suggest that the Bose-Fermi system undergoes a BCS-like phase transition for a suitable choice of the coupling constant.

gr-qc↗