10,242 research outputs found
Gravitational wave background from neutron star phase transition for a new class of equation of state
We study the generation of a stochastic gravitational wave (GW) background
produced by a population of neutron stars (NSs) which go over a hadron-quark
phase transition in its inner shells. We obtain, for example, that the NS phase
transition, in cold dark matter scenarios, could generate a stochastic GW
background with a maximum amplitude of , in the
frequency band for stars forming at redshifts of up
to We study the possibility of detection of this isotropic GW
background by correlating signals of a pair of `advanced' LIGO observatories.Comment: 7 pages, 1 figur
Coalescence Rate of Supermassive Black Hole Binaries Derived from Cosmological Simulations: Detection Rates for LISA and ET
The coalescence history of massive black holes has been derived from
cosmological simulations, in which the evolution of those objects and that of
the host galaxies are followed in a consistent way. The present study indicates
that supermassive black holes having masses greater than underwent up to 500 merger events along their history. The derived
coalescence rate per comoving volume and per mass interval permitted to obtain
an estimate of the expected detection rate distribution of gravitational wave
signals ("ring-down") along frequencies accessible by the planned
interferometers either in space (LISA) or in the ground (Einstein). For LISA,
in its original configuration, a total detection rate of about is
predicted for events having a signal-to-noise ratio equal to 10, expected to
occur mainly in the frequency range . For the Einstein gravitational
wave telescope, one event each 14 months down to one event each 4 years is
expected with a signal-to-noise ratio of 5, occurring mainly in the frequency
interval . The detection of these gravitational signals and their
distribution in frequency would be in the future an important tool able to
discriminate among different scenarios explaining the origin of supermassive
black holes.Comment: 18 pages, 7 figures, to appear in the IJMP
Comparison between the Torquato-Rintoul theory of the interface effect in composite media and elementary results
We show that the interface effect on the properties of composite media
recently proposed by Torquato and Rintoul (TR) [Phys. Rev. Lett. 75, 4067
(1995)] is in fact elementary, and follows directly from taking the limit in
the dipolar polarizability of a coated sphere: the TR ``critical values'' are
simply those that make the dipolar polarizability vanish. Furthermore, the new
bounds developed by TR either coincide with the Clausius-Mossotti (CM) relation
or provide poor estimates. Finally, we show that the new bounds of TR do not
agree particularly well with the original experimental data that they quote.Comment: 13 pages, Revtex, 8 Postscript figure
- …