55 research outputs found
Searching for gravitational waves with the LIGO and Virgo interferometers
The first generation of ground-based interferometric gravitational wave
detectors, LIGO, GEO and Virgo, have operated and taken data at their design
sensitivities over the last few years. The data has been examined for the
presence of gravitational wave signals. Presented here is a comprehensive
review of the most significant results. The network of detectors is currently
being upgraded and extended, providing a large likelihood for observations.
These future prospects will also be discussed.Comment: 33 pages, 4 figures, published in Comptes Rendus Physiqu
Understanding the progenitor formation galaxies of merging binary black holes
With nearly a hundred gravitational wave detections, the origin of black hole
mergers has become a key question. Here, we focus on understanding the typical
galactic environment in which binary black hole mergers arise. To this end, we
synthesize progenitors of binary black hole mergers as a function of the
redshift of progenitor formation, present-day formation galaxy mass, and
progenitor stellar metallicity for star formation and binary evolution
models. We provide guidelines to infer the formation galaxy properties and time
of formation, highlighting the interplay between the star formation rate and
the efficiency of forming merging binary black holes from binary stars, both of
which strongly depend on metallicity. We find that across models, over 50% of
BBH mergers have a progenitor metallicity of a few tenths of Solar metallicity,
however, inferring formation galaxy properties strongly depends on both the
binary evolution model and global metallicity evolution. The numerous, low-mass
black holes () trace the bulk of the star
formation in galaxies heavier than the Milky Way (
). In contrast, heavier BBH mergers
typically stem from larger black holes forming in lower metallicity dwarf
galaxies ( ). We find that
the progenitors of detectable binary black holes tend to arise from dwarf
galaxies at a lower formation redshift (). We also produce a
posterior probability of the progenitor environment for any detected
gravitational wave signal. For the massive GW150914 merger, we show that it
likely came from a very low metallicity (
) environment.Comment: 17 pages, 15 figures, 1 table, Accpeted for publication by MNRA
On the background estimation by time slides in a network of gravitational wave detectors
Time shifting the outputs of Gravitational Wave detectors operating in
coincidence is a convenient way to estimate the background in a search for
short duration signals. However this procedure is limited as increasing
indefinitely the number of time shifts does not provide better estimates. We
show that the false alarm rate estimation error saturates with the number of
time shifts. In particular, for detectors with very different trigger rates
this error saturates at a large value. Explicit computations are done for 2
detectors, and for 3 detectors where the detection statistic relies on the
logical ``OR'' of the coincidences of the 3 couples in the network.Comment: accepted for publication in CQ
Coincidence and coherent data analysis methods for gravitational wave bursts in a network of interferometric detectors
Network data analysis methods are the only way to properly separate real
gravitational wave (GW) transient events from detector noise. They can be
divided into two generic classes: the coincidence method and the coherent
analysis. The former uses lists of selected events provided by each
interferometer belonging to the network and tries to correlate them in time to
identify a physical signal. Instead of this binary treatment of detector
outputs (signal present or absent), the latter method involves first the
merging of the interferometer data and looks for a common pattern, consistent
with an assumed GW waveform and a given source location in the sky. The
thresholds are only applied later, to validate or not the hypothesis made. As
coherent algorithms use a more complete information than coincidence methods,
they are expected to provide better detection performances, but at a higher
computational cost. An efficient filter must yield a good compromise between a
low false alarm rate (hence triggering on data at a manageable rate) and a high
detection efficiency. Therefore, the comparison of the two approaches is
achieved using so-called Receiving Operating Characteristics (ROC), giving the
relationship between the false alarm rate and the detection efficiency for a
given method. This paper investigates this question via Monte-Carlo
simulations, using the network model developed in a previous article.Comment: Spelling mistake corrected in one author's nam
Formalism for power spectral density estimation for non-identical and correlated noise using the null channel in Einstein Telescope
Several proposed gravitational wave interferometers have a triangular
configuration, such as the Einstein Telescope and the Laser Interferometer
Space Antenna. For such a configuration one can construct a unique null channel
insensitive to gravitational waves from all directions. We expand on earlier
work and describe how to use the null channel formalism to estimate the power
spectral density for the Einstein Telescope interferometers with non-identical
as well as correlated noise sources. The formalism is illustrated with two
examples in the context of the Einstein Telescope, with increasing degrees of
complexity and realism. By using known mixtures of noises we show the formalism
is mathematically correct and internally consistent. Finally we highlight
future research needed to use this formalism as an ingredient for a Bayesian
estimation framework.Comment: The results have been updated (10/10/2022). Please refer to this new
versio
Comparison of filters for detecting gravitational wave bursts in interferometric detectors
Filters developed in order to detect short bursts of gravitational waves in
interferometric detector outputs are compared according to three main points.
Conventional Receiver Operating Characteristics (ROC) are first built for all
the considered filters and for three typical burst signals. Optimized ROC are
shown for a simple pulse signal in order to estimate the best detection
efficiency of the filters in the ideal case, while realistic ones obtained with
filters working with several ``templates'' show how detection efficiencies can
be degraded in a practical implementation. Secondly, estimations of biases and
statistical errors on the reconstruction of the time of arrival of pulse-like
signals are then given for each filter. Such results are crucial for future
coincidence studies between Gravitational Wave detectors but also with neutrino
or optical detectors. As most of the filters require a pre-whitening of the
detector noise, the sensitivity to a non perfect noise whitening procedure is
finally analysed. For this purpose lines of various frequencies and amplitudes
are added to a Gaussian white noise and the outputs of the filters are studied
in order to monitor the excess of false alarms induced by the lines. The
comparison of the performances of the different filters finally show that they
are complementary rather than competitive.Comment: 32 pages (14 figures), accepted for publication in Phys. Rev.
Bayesian reconstruction of gravitational wave burst signals from simulations of rotating stellar core collapse and bounce
Presented in this paper is a technique that we propose for extracting the
physical parameters of a rotating stellar core collapse from the observation of
the associated gravitational wave signal from the collapse and core bounce.
Data from interferometric gravitational wave detectors can be used to provide
information on the mass of the progenitor model, precollapse rotation and the
nuclear equation of state. We use waveform libraries provided by the latest
numerical simulations of rotating stellar core collapse models in general
relativity, and from them create an orthogonal set of eigenvectors using
principal component analysis. Bayesian inference techniques are then used to
reconstruct the associated gravitational wave signal that is assumed to be
detected by an interferometric detector. Posterior probability distribution
functions are derived for the amplitudes of the principal component analysis
eigenvectors, and the pulse arrival time. We show how the reconstructed signal
and the principal component analysis eigenvector amplitude estimates may
provide information on the physical parameters associated with the core
collapse event.Comment: 17 pages, 9 figure
Reconstruction of source location in a network of gravitational wave interferometric detectors
This paper deals with the reconstruction of the direction of a gravitational
wave source using the detection made by a network of interferometric detectors,
mainly the LIGO and Virgo detectors. We suppose that an event has been seen in
coincidence using a filter applied on the three detector data streams. Using
the arrival time (and its associated error) of the gravitational signal in each
detector, the direction of the source in the sky is computed using a chi^2
minimization technique. For reasonably large signals (SNR>4.5 in all
detectors), the mean angular error between the real location and the
reconstructed one is about 1 degree. We also investigate the effect of the
network geometry assuming the same angular response for all interferometric
detectors. It appears that the reconstruction quality is not uniform over the
sky and is degraded when the source approaches the plane defined by the three
detectors. Adding at least one other detector to the LIGO-Virgo network reduces
the blind regions and in the case of 6 detectors, a precision less than 1
degree on the source direction can be reached for 99% of the sky.Comment: Accepted in Phys. Rev.
An Optically Targeted Search for Gravitational Waves emitted by Core-Collapse Supernovae during the Third Observing Run of Advanced LIGO and Advanced Virgo
We present the results from a search for gravitational-wave transients associated with core-collapse supernovae observed optically within 30 Mpc during the third observing run of Advanced LIGO and Advanced Virgo. No gravitational wave associated with a core-collapse supernova has been identified. We then report the detection efficiency for a variety of possible gravitational-wave emissions. For neutrino-driven explosions, the distance at which we reach 50% detection efficiency is up to 8.9 kpc, while more energetic magnetorotationally-driven explosions are detectable at larger distances. The distance reaches for selected models of the black hole formation, and quantum chromodynamics phase transition are also provided. We then constrain the core-collapse supernova engine across a wide frequency range from 50 Hz to 2 kHz. The upper limits on gravitational-wave energy and luminosity emission are at low frequencies down to 10â4Mâc2 and 5Ă10â4Mâc2/s, respectively. The upper limits on the proto-neutron star ellipticity are down to 5 at high frequencies. Finally, by combining the results obtained with the data from the first and second observing runs of LIGO and Virgo, we improve the constraints of the parameter spaces of the extreme emission models. Specifically, the proto-neutron star ellipticities for the long-lasting bar mode model are down to 1 for long emission (1 s) at high frequency
An elliptical tiling method to generate a 2-dimensional set of templates for gravitational wave search
Searching for a signal depending on unknown parameters in a noisy background
with matched filtering techniques always requires an analysis of the data with
several templates in parallel in order to ensure a proper match between the
filter and the real waveform. The key feature of such an implementation is the
design of the filter bank which must be small to limit the computational cost
while keeping the detection efficiency as high as possible. This paper presents
a geometrical method which allows one to cover the corresponding physical
parameter space by a set of ellipses, each of them being associated to a given
template. After the description of the main characteristics of the algorithm,
the method is applied in the field of gravitational wave (GW) data analysis,
for the search of damped sine signals. Such waveforms are expected to be
produced during the de-excitation phase of black holes -- the so-called
'ringdown' signals -- and are also encountered in some numerically computed
supernova signals.Comment: Accepted in PR
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