690 research outputs found
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
A Mock Data and Science Challenge for Detecting an Astrophysical Stochastic Gravitational-Wave Background with Advanced LIGO and Advanced Virgo
The purpose of this mock data and science challenge is to prepare the data
analysis and science interpretation for the second generation of
gravitational-wave experiments Advanced LIGO-Virgo in the search for a
stochastic gravitational-wave background signal of astrophysical origin. Here
we present a series of signal and data challenges, with increasing complexity,
whose aim is to test the ability of current data analysis pipelines at
detecting an astrophysically produced gravitational-wave background, test
parameter estimation methods and interpret the results. We introduce the
production of these mock data sets that includes a realistic observing scenario
data set where we account for different sensitivities of the advanced detectors
as they are continuously upgraded toward their design sensitivity. After
analysing these with the standard isotropic cross-correlation pipeline we find
that we are able to recover the injected gravitational-wave background energy
density to within for all of the data sets and present the results
from the parameter estimation. The results from this mock data and science
challenge show that advanced LIGO and Virgo will be ready and able to make a
detection of an astrophysical gravitational-wave background within a few years
of operations of the advanced detectors, given a high enough rate of compact
binary coalescing events
Revisiting coincidence rate between Gravitational Wave detection and short Gamma-Ray Burst for the Advanced and third generation
We use realistic Monte-Carlo simulations including both gravitational-wave
and short gamma-ray burst selection effects to revisit the coincident rate of
binary systems composed of two neutron stars or a neutron star and a black
hole. We show that the fraction of GW triggers that can be observed in
coincidence with sGRBs is proportional to the beaming factor at , but
increases with the distance, until it reaches 100 \% at the GW detector horizon
distance. When this is taken into account the rate is improved by a factor of
compared to the simple beaming factor correction. We provide an estimate
of the performance future GRB detectors should achieve in order to fully
exploit the potentiality of the planned third generation GW antenna Einstein
Telescope, and we propose a simple method to constrain the beaming angle of
sGRBs.Comment: 31 pages, 11 figures, 4 tables, accepted for publication in Ap
A time frequency analysis of wave packet fractional revivals
We show that the time frequency analysis of the autocorrelation function is,
in many ways, a more appropriate tool to resolve fractional revivals of a wave
packet than the usual time domain analysis. This advantage is crucial in
reconstructing the initial state of the wave packet when its coherent structure
is short-lived and decays before it is fully revived. Our calculations are
based on the model example of fractional revivals in a Rydberg wave packet of
circular states. We end by providing an analytical investigation which fully
agrees with our numerical observations on the utility of time-frequency
analysis in the study of wave packet fractional revivals.Comment: 9 pages, 4 figure
Transverse confinement in stochastic cooling of trapped atoms
Stochastic cooling of trapped atoms is considered for a laser-beam
configuration with beam waists equal or smaller than the extent of the atomic
cloud. It is shown, that various effects appear due to this transverse
confinement, among them heating of transverse kinetic energy. Analytical
results of the cooling in dependence on size and location of the laser beam are
presented for the case of a non-degenerate vapour.Comment: 14 pages, 5 figures, accepted for publication in Journal of Optics
Ferromagnetism in a lattice of Bose condensates
We show that an ensemble of spinor Bose-Einstein condensates confined in a
one dimensional optical lattice can undergo a ferromagnetic phase transition
and spontaneous magnetization arises due to the magnetic dipole-dipole
interaction. This phenomenon is analogous to ferromagnetism in solid state
physics, but occurs with bosons instead of fermions.Comment: 4 pages, 2 figure
Bloch oscillations and mean-field effects of Bose-Einstein condensates in 1-D optical lattices
We have loaded Bose-Einstein condensates into one-dimensional, off-resonant
optical lattices and accelerated them by chirping the frequency difference
between the two lattice beams. For small values of the lattice well-depth,
Bloch oscillations were observed. Reducing the potential depth further,
Landau-Zener tunneling out of the lowest lattice band, leading to a breakdown
of the oscillations, was also studied and used as a probe for the effective
potential resulting from mean-field interactions as predicted by Choi and Niu
[Phys. Rev. Lett. {\bf 82}, 2022 (1999)]. The effective potential was measured
for various condensate densities and trap geometries, yielding good qualitative
agreement with theoretical calculations.Comment: 5 pages, 3 figures; accepted for publication in Physical Review
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