5 research outputs found
Relativistic Neutron Stars: Rheological Type Extensions of the Equations of State
Based on the Rheological Paradigm, one has extended the equations of state
for relativistic spherically symmetric static neutron stars, taking into
consideration the derivative of the matter pressure along the so-called
director four-vector. The modified equations of state are applied to the model
of a zero-temperature neutron condensate. This model includes one new parameter
with the dimensionality of length, which describes the rheological type
screening inside the neutron star. As an illustration of the new approach, one
has considered the rheological type generalization of the non-relativistic
Lane-Emden theory and found the numerical profiles of the pressure for a number
of values of the new guiding parameter. One has found that the rheological type
self-interaction makes the neutron star more compact, since the radius of the
star, related to the first null of the pressure profile, decreases when the
modulus of the rheological type guiding parameter grows.Comment: 14 pages, 1 figure, 1 tabl
Radiation from a charge circulating inside a waveguide with dielectric filling
The emitted power of the radiation from a charged particle moving uniformly
on a circle inside a cylindrical waveguide is considered. The expressions for
the energy flux of the radiation passing through the waveguide cross-section
are derived for both TE and TM waves. The results of the numerical evaluation
are presented for the number of emitted quanta depending on the waveguide
radius, the radius of the charge rotation orbit and dielectric permittivity of
the filling medium. These results are compared with the corresponding
quantities for the synchrotron radiation in a homogeneous medium.Comment: 10 pages, Latex, four EPS figure
Electromagnetic Casimir Effect in AdS Spacetime
We investigate the vacuum expectation value (VEV) of the energy-momentum tensor for the electromagnetic field in anti-de Sitter (AdS) spacetime in the presence of a boundary parallel to the AdS horizon. On the boundary, the field obeys the generalized perfect conductor boundary condition. The VEV of the energy-momentum tensor is decomposed into the boundary-free and boundary-induced contributions. In this way, for points away from the boundary, the renormalization is reduced to that for AdS spacetime without the boundary. The boundary-induced energy density is negative everywhere, and the normal stress is positive in the region between the boundary and the AdS boundary and is negative in the region between the boundary and the AdS horizon. Near both the AdS boundary and horizon, the boundary-induced VEV decays exponentially as a function of the corresponding proper distance. Applications are given for even and odd vector fields in Randall–Sundrum model with a single brane