162 research outputs found
On the peculiarities in the rotational frequency evolution of isolated neutron stars
The measurements of pulsar frequency second derivatives have shown that they
are times larger than expected for standard pulsar spin-down law,
and are even negative for about half of pulsars. We explain these paradoxical
results on the basis of the statistical analysis of the rotational parameters
, and of the subset of 295 pulsars taken mostly
from the ATNF database. We have found a strong correlation between
and for both and , as well as between
and . We interpret these dependencies as evolutionary ones due
to being nearly proportional to the pulsars' age. The derived
statistical relations as well as "anomalous" values of are well
described by assuming the long-time variations of the spin-down rate. The
pulsar frequency evolution, therefore, consists of secular change of
, and according to the power
law with , the irregularities, observed within a timespan as a
timing noise, and the variations on the timescale larger than that timespan --
several tens of years.Comment: 4 pages, 3 figures. Accepted for publication in ApSS, in the
proceedings of the conference "Isolated Neutron Stars: from the Interior to
the Surface", London, April 2006; eds. S. Zane, R. Turolla and D. Pag
Deformation of the Planetary Orbits Caused by the Time Dependent Gravitational Potential in the Universe
In the paper are studied the deformations of the planetary orbits caused by
the time dependent gravitational potential in the universe. It is shown that
the orbits are not axially symmetric and the time dependent potential does not
cause perihelion precession. It is found a simple formula for the change of the
orbit period caused by the time dependent gravitational potential and it is
tested for two binary pulsars.Comment: 7 page
Gravitational dipole radiations from binary systems
We investigate the possibility of generating sizeable dipole radiations in
relativistic theories of gravity. Optimal parameters to observe their effects
through the orbital period decay of binary star systems are discussed.
Constraints on gravitational couplings beyond general relativity are derived.Comment: One comment added, accepted for publication in Phys. Rev.
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