INVESTIGADORES
BARRACO DIAZ Daniel Eugenio
artículos
Título:
A Stelar model in a Fourth Order Theory of Gravity
Autor/es:
DANIEL BARRACO AND VICTOR HAMITY
Revista:
PHYSICAL REVIEW D - PARTICLE AND FILDS
Referencias:
Año: 1998 vol. 57 p. 954 - 960
ISSN:
0556-2821
Resumen:
Within a fourth order theory of gravity, we obtain the approximation
equations in first order of the coupling constant α of the quadratic
term in the curvature and apply these equations to discuss a
spherically symmetric perfect fluid stellar model in a weak field limit
up to second order in the mass density ρ. We find, unlike general
relativity (GR), that the continuity of the metric does not allow for a
discontinuous mass density; i.e., for any bounded distribution of
matter the pressure and the
mass density have to be zero at the boundary. We show that the active
mass of the fourth order theory is different than the active mass in
GR. Furthermore, for a hard core star model, we find the explicit
solution for the pressure and investigate the upper bound on the active
mass of the star by assuming that matter couples minimally in the
Jordan conformal frame and by applying the dominant energy condition to
the perfect fluid at the center of the star. We show that there exist
values of α and of the radius R for which this mass of the system does not have an upper bound.