101 research outputs found
Observational discrimination of Eddington-inspired Born-Infeld gravity from general relativity
Direct observations of neutron stars could tell us an imprint of modified
gravity. However, it is generally difficult to resolve the degeneracy due to
the uncertainties in equation of state (EOS) of neutron star matter and in
gravitational theories. In this paper, we are successful to find the
observational possibility to distinguish Eddington-inspired Born-Infeld gravity
(EiBI) from general relativity. We show that the radii of neutron stars with
are strongly correlated with the neutron skin thickness of
Pb independently of EOS, while this correlation depends on the
coupling constant in EiBI. As a result, via the direct observations of radius
of neutron star with and the measurements of neutron skin
thickness of Pb by the terrestrial experiments, one could not only
discriminate EiBI from general relativity but also estimate the coupling
constant in EiBI.Comment: accepted for publication in PR
Stellar oscillations in Eddington-inspired Born-Infeld gravity
We consider the stellar oscillations of relativistic stars in the
Eddington-inspired Born-Infeld gravity (EiBI). In order to examine the specific
frequencies, we derive the perturbation equations governing the stellar
oscillations in EiBI by linearizing the field equations, and numerically
determine the oscillation frequencies as changing the coupling parameter in
EiBI, , and stellar models. As a result, we find that the frequencies
depend strongly on the value of , where the frequencies in EiBI with
negative become higher and those with positive become lower
than the expectations in general relativity. We also find that, via the
observation of the fundamental frequency, one could distinguish EiBI with
from general relativity, independently of
the equation of state (EOS) for neutron star matter, where denotes
the nuclear saturation density and become dimensionless
parameter. With the further constraints on EOS, one might distinguish EiBI even
with from general relativity.Comment: accepted for publication in PR
Slowly Rotating Relativistic Stars in Tensor-Vector-Scalar Theory
In order to examine the rotational effect around neutron star in
tensor-vector-scalar (TeVeS) theory, we consider the slowly rotating
relativistic stars with a uniform angular velocity. As a result, we find that
similar to the case in general relativity (GR), the angular momentum is
proportional to the angular velocity. Additionally, as the value of coupling
constant becomes higher, the frame dragging in TeVeS becomes quite
different distribution from that in GR, where we can also see the deviation
even in the interior of star. While with smaller value of , although the
frame dragging approaches to that expected in GR, the induced vector field due
to the rotation does not vanish and still exists. Thus, through the
observations associated with relativistic object, one could be possible to
distinguish the gravitational theory in strong field regime even in the case
that the value of coupling constant is quite small.Comment: Accepted in Phys.Rev.
- …