927 research outputs found
Astrophysical Sources of Stochastic Gravitational-Wave Background
We review the spectral properties of stochastic backgrounds of astrophysical
origin and discuss how they may differ from the primordial contribution by
their statistical properties. We show that stochastic searches with the next
generation of terrestrial interferometers could put interesting constrains on
the physical properties of astrophysical populations, such as the ellipticity
and magnetic field of magnetars, or the coalescence rate of compact binaries.Comment: 12 pages, 3 figures,accepted for publication in CQG, GWDAW12
conference proceedings version corrected in comparison published version
where we found an error in equation (4
Second Einstein Telescope Mock Science Challenge : Detection of the GW Stochastic Background from Compact Binary Coalescences
We present the results of the search for an astrophysical gravitational-wave
stochastic background during the second Einstein Telescope mock data and
science challenge. Assuming that the loudest sources can be detected
individually and removed from the data, we show that the residual background
can be recovered with an accuracy of with the standard cross-correlation
statistic, after correction of a systematic bias due to the non-isotropy of the
sources.Comment: 15 pages, 4 figures, accepted for publication in Physical Review
Gravitation Wave Emission from Radio Pulsars Revisited
We report a new pulsar population synthesis based on Monte Carlo techniques,
aiming to estimate the contribution of galactic radio pulsars to the continuous
gravitational wave emission. Assuming that the rotation periods of pulsars at
birth have a Gaussian distribution, we find that the average initial period is
290 ms. The number of objects with periods equal to or less than 0.4 s, and
therefore capable of being detected by an interferometric gravitational antenna
like VIRGO, is of the order of 5100-7800. With integration times lasting
between 2 and 3 yr, our simulations suggest that about two detections should be
possible, if the mean equatorial ellipticity of the pulsars is
=10. A mean ellipticity an order of magnitude higher increases the
expected number of detections to 12-18, whereas for , no
detections are expectedComment: accepted for publication in A&A, 9 pages, 8 figure
Evidence for a dual population of neutron star mergers from short Gamma-Ray Burst observations
Short duration Gamma-Ray Bursts are thought to originate from the coalescence
of neutron stars in binary systems. They are detected as a brief ( 2s),
intense flash of gamma-ray radiation followed by a weaker, rapidly decreasing
afterglow. They are expected to be detected by Advanced LIGO and Virgo when
their sensitivity will be low enough. In a recent study we identified a
population of short Gamma-Ray Bursts that are intrinsically faint and nearby.
Here we provide evidence in favor of the existence of this new population that
can hardly be reproduced with a model of field neutron star binary
coalescences. We propose that these systems may be produced dynamically in
globular clusters, and may result from the merger of a black hole and a neutron
star. The advanced LIGO and Virgo observation of a high rate of NSBH mergers
compatible with the dynamical formation in globular clusters would be a
confirmation of this hypothesis and would enable for the derivation of the mass
function of black holes inside globular clusters, as well as the luminosity
function of faint short GRBs.Comment: 15 pages, 5 figures, 1 table, submitted to Ap
Searching Gravitational Waves from Pulsars, Using Laser Beam Interferometers
We use recent population synthesis results to investigate the distribution of
pulsars in the frequency space, having a gravitational strain high enough to be
detected by the future generations of laser beam interferometers.
We find that until detectors become able to recover the entire population,
the frequency distribution of the 'detectable' population will be very
dependent on the detector noise curve. Assuming a mean equatorial deformation
, the optimal frequency is around 450 Hz for interferometers
of the first generation (LIGO or VIRGO) and shifts toward 85 Hz for advanced
detectors. An interesting result for future detection stategies is the
significant narrowing of the distribution when improving the sensitivity: with
an advanced detector, it is possible to have 90% of detection probability while
exploring less than 20% of the parameter space (7.5% in the case of ). In addition, we show that in most cases the spindown of
'detectable' pulsars represents a period shift of less than a tens of
nanoseconds after one year of observation, making them easier to follow in the
frequency space.Comment: 5 pages, 3 figures accepted for publication in Astronomy &
Astrophysic
Stochastic backgrounds of gravitational waves from extragalactic sources
Astrophysical sources emit gravitational waves in a large variety of
processes occurred since the beginning of star and galaxy formation. These
waves permeate our high redshift Universe, and form a background which is the
result of the superposition of different components, each associated to a
specific astrophysical process. Each component has different spectral
properties and features that it is important to investigate in view of a
possible, future detection. In this contribution, we will review recent
theoretical predictions for backgrounds produced by extragalactic sources and
discuss their detectability with current and future gravitational wave
observatories.Comment: 10 pages, 9 figures, proceedings of the GWDAW 10 Conference,
submitted to Class. & Quantum Gra
Stochastic Gravitational Wave Background from Coalescing Binary Black Holes
We estimate the stochastic gravitational wave (GW) background signal from the
field population of coalescing binary stellar mass black holes (BHs) throughout
the Universe. This study is motivated by recent observations of BH-Wolf-Rayet
star systems and by new estimates in the metallicity abundances of star forming
galaxies that imply BH-BH systems are more common than previously assumed.
Using recent analytical results of the inspiral-merger-ringdown waveforms for
coalescing binary BH systems, we estimate the resulting stochastic GW
background signal. Assuming average quantities for the single source energy
emissions, we explore the parameter space of chirp mass and local rate density
required for detection by advanced and third generation interferometric GW
detectors. For an average chirp mass of 8.7, we find that detection
through 3 years of cross-correlation by two advanced detectors will require a
rate density, . Combining data from
multiple pairs of detectors can reduce this limit by up to 40%. Investigating
the full parameter space we find that detection could be achieved at rates for populations of coalescing binary BH
systems with average chirp masses of which are predicted by
recent studies of BH-Wolf-Rayet star systems. While this scenario is at the
high end of theoretical estimates, cross-correlation of data by two Einstein
Telescopes could detect this signal under the condition . Such a signal could potentially mask a primordial
GW background signal of dimensionless energy density, , around the (1--500) Hz frequency range.Comment: 22 pages, 5 figures, 2 tables, Accepted for publication by Ap
Effect of metallicity on the gravitational-wave signal from the cosmological population of compact binary coalescences
Recent studies on stellar evolution have shown that the properties of compact
objects strongly depend on the metallicity of the environment in which they
were formed. Using some very simple assumptions on the metallicity of the
stellar populations, we explore how this property affects the unresolved
gravitational-wave background from extragalactic compact binaries. We obtained
a suit of models using population synthesis code, estimated the
gravitational-wave background they produce, and discuss its detectability with
second- (advanced LIGO, advanced Virgo) and third- (Einstein Telescope)
generation detectors. Our results show that the background is dominated by
binary black holes for all considered models in the frequency range of
terrestrial detectors, and that it could be detected in most cases by advanced
LIGO/Virgo, and with Einstein Telescope with a very high signal-to-noise ratio.
The observed peak in a gravitational wave spectrum depends on the metallicity
of the stellar population.Comment: 9 pages, 5 figures, accepted to A&
Stochastic background from extra-galactic double neutron stars
We present Monte Carlo simulations of the extra galactic population of
inspiralling double neutron stars, and estimate its contribution to the
astrophysical gravitational wave background, in the frequency range of ground
based interferometers, corresponding to the last thousand seconds before the
last stable orbit when more than 96 percent of the signal is released. We show
that sources at redshift z>0.5 contribute to a truly continuous background
which may be detected by correlating third generation interferometers.Comment: 13 pages, 7 figures - proceeding of a talk given at the 11th GWDAW,
to appear in CQ
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