Cemsinan Deliduman, K. Y. Ekşi, Vildan Keleş
We study the structure of neutron stars in R+\beta R^{\mu \nu} R_{\mu \nu}
gravity model with perturbative method. We obtain mass-radius relations for six
representative equations of state (EOSs). We find that deviations from the
results of general relativity, comparable to the variations due to using
different EoSs, are induced for |\beta| ~ 10^11 cm^2. Some of the soft EoSs
that are excluded within the framework of general relativity can be reconciled
for certain values of \beta\ of this order with the 2 solar mass neutron star
recently observed. For some of the EoSs we find that a new solution branch,
which allows highly massive neutron stars, exists for values of \beta\ greater
than a few 10^11 cm^2. We find constraints on \beta\ for a variety of EoSs
using the recent observational constraints on the mass-radius relation. The
associated length scale \sqrt{\beta} ~ 10^6 cm is of the order of the the
typical radius of neutron stars, the probe used in this test. This implies that
the true value of \beta\ is most likely much smaller than 10^11 cm^2.
View original:
http://arxiv.org/abs/1112.4154
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