85 research outputs found
The search for spinning black hole binaries in mock LISA data using a genetic algorithm
Coalescing massive Black Hole binaries are the strongest and probably the
most important gravitational wave sources in the LISA band. The spin and
orbital precessions bring complexity in the waveform and make the likelihood
surface richer in structure as compared to the non-spinning case. We introduce
an extended multimodal genetic algorithm which utilizes the properties of the
signal and the detector response function to analyze the data from the third
round of mock LISA data challenge (MLDC 3.2). The performance of this method is
comparable, if not better, to already existing algorithms. We have found all
five sources present in MLDC 3.2 and recovered the coalescence time, chirp
mass, mass ratio and sky location with reasonable accuracy. As for the orbital
angular momentum and two spins of the Black Holes, we have found a large number
of widely separated modes in the parameter space with similar maximum
likelihood values.Comment: 25 pages, 9 figure
LISACode : A scientific simulator of LISA
A new LISA simulator (LISACode) is presented. Its ambition is to achieve a
new degree of sophistication allowing to map, as closely as possible, the
impact of the different sub-systems on the measurements. LISACode is not a
detailed simulator at the engineering level but rather a tool whose purpose is
to bridge the gap between the basic principles of LISA and a future,
sophisticated end-to-end simulator. This is achieved by introducing, in a
realistic manner, most of the ingredients that will influence LISA's
sensitivity as well as the application of TDI combinations. Many user-defined
parameters allow the code to study different configurations of LISA thus
helping to finalize the definition of the detector. Another important use of
LISACode is in generating time series for data analysis developments
The search for black hole binaries using a genetic algorithm
In this work we use genetic algorithm to search for the gravitational wave
signal from the inspiralling massive Black Hole binaries in the simulated LISA
data. We consider a single signal in the Gaussian instrumental noise. This is a
first step in preparation for analysis of the third round of the mock LISA data
challenge. We have extended a genetic algorithm utilizing the properties of the
signal and the detector response function. The performance of this method is
comparable, if not better, to already existing algorithms.Comment: 11 pages, 4 figures, proceeding for GWDAW13 (Puerto Rico
TDI noises transfer functions for LISA
The LISA mission is the future space-based gravitational wave (GW)
observatory of the European Space Agency. It is formed by 3 spacecraft
exchanging laser beams in order to form multiple real and virtual
interferometers. The data streams to be used in order to extract the large
number and variety of GW sources are Time-Delay Interferometry (TDI) data. One
important processing to produce these data is the TDI on-ground processing
which recombines multiple interferometric on-board measurements to remove
certain noise sources from the data such as laser frequency noise or spacecraft
jitter. The LISA noise budget is therefore expressed at the TDI level in order
to account for the different TDI transfer functions applied for each noise
source and thus estimate their real weight on mission performance. In order to
derive a usable form of these transfer functions, a model of the beams, the
measurements, and TDI have been developed, and several approximation have been
made. A methodology for such a derivation has been established, as well as
verification procedures. It results in a set of transfer functions, which are
now used by the LISA project, in particular in its performance model. Using
these transfer functions, realistic noise curves for various instrumental
configurations are provided to data analysis algorithms and used for instrument
design.Comment: 15 pages, 7 figure
Science with the space-based interferometer LISA. V Extreme mass-ratio inspirals
The space-based Laser Interferometer Space Antenna (LISA) will be able to
observe the gravitational-wave signals from systems comprised of a massive
black hole and a stellar-mass compact object. These systems are known as
extreme-mass-ratio inspirals (EMRIs) and are expected to complete - cycles in band, thus allowing exquisite measurements of their
parameters. In this work, we attempt to quantify the astrophysical
uncertainties affecting the predictions for the number of EMRIs detectable by
LISA, and find that competing astrophysical assumptions produce a variance of
about three orders of magnitude in the expected intrinsic EMRI rate. However,
we find that irrespective of the astrophysical model, at least a few EMRIs per
year should be detectable by the LISA mission, with up to a few thousands per
year under the most optimistic astrophysical assumptions. We also investigate
the precision with which LISA will be able to extract the parameters of these
sources. We find that typical fractional statistical errors with which the
intrinsic parameters (redshifted masses, massive black hole spin and orbital
eccentricity) can be recovered are -. Luminosity
distance (which is required to infer true masses) is inferred to about
precision and sky position is localized to a few square degrees, while tests of
the multipolar structure of the Kerr metric can be performed to percent-level
precision or better.Comment: 13 figures, 22 pages; updated to match published versio
Low-frequency gravitational-wave science with eLISA/NGO
We review the expected science performance of the New Gravitational-Wave
Observatory (NGO, a.k.a. eLISA), a mission under study by the European Space
Agency for launch in the early 2020s. eLISA will survey the low-frequency
gravitational-wave sky (from 0.1 mHz to 1 Hz), detecting and characterizing a
broad variety of systems and events throughout the Universe, including the
coalescences of massive black holes brought together by galaxy mergers; the
inspirals of stellar-mass black holes and compact stars into central galactic
black holes; several millions of ultracompact binaries, both detached and mass
transferring, in the Galaxy; and possibly unforeseen sources such as the relic
gravitational-wave radiation from the early Universe. eLISA's high
signal-to-noise measurements will provide new insight into the structure and
history of the Universe, and they will test general relativity in its
strong-field dynamical regime.Comment: 20 pages, 8 figures, proceedings of the 9th Amaldi Conference on
Gravitational Waves. Final journal version. For a longer exposition of the
eLISA science case, see http://arxiv.org/abs/1201.362
Constraining the dark energy equation of state using LISA observations of spinning Massive Black Hole binaries
Gravitational wave signals from coalescing Massive Black Hole (MBH) binaries
could be used as standard sirens to measure cosmological parameters. The future
space based gravitational wave observatory Laser Interferometer Space Antenna
(LISA) will detect up to a hundred of those events, providing very accurate
measurements of their luminosity distances. To constrain the cosmological
parameters we also need to measure the redshift of the galaxy (or cluster of
galaxies) hosting the merger. This requires the identification of a distinctive
electromagnetic event associated to the binary coalescence. However, putative
electromagnetic signatures may be too weak to be observed. Instead, we study
here the possibility of constraining the cosmological parameters by enforcing
statistical consistency between all the possible hosts detected within the
measurement error box of a few dozen of low redshift (z<3) events. We construct
MBH populations using merger tree realizations of the dark matter hierarchy in
a LambdaCDM Universe, and we use data from the Millennium simulation to model
the galaxy distribution in the LISA error box. We show that, assuming that all
the other cosmological parameters are known, the parameter w describing the
dark energy equation of state can be constrained to a 4-8% level (2sigma
error), competitive with current uncertainties obtained by type Ia supernovae
measurements, providing an independent test of our cosmological model.Comment: 12 pages, 8 figures, revised version to address referee's comments,
submitted to Ap
Low-Frequency Gravitational-Wave Science with eLISA/ NGO
We review the expected science performance of the New Gravitational-Wave Observatory (NGO, a.k.a. eLISA), a mission under study by the European Space Agency for launch in the early 2020s. eLISA will survey the low-frequency gravitational-wave sky (from 0.1 mHz to 1 Hz), detecting and characterizing a broad variety of systems and events throughout the Universe, including the coalescences of massive black holes brought together by galaxy mergers; the inspirals of stellar-mass black holes and compact stars into central galactic black holes; several millions of ultracompact binaries, both detached and mass transferring, in the Galaxy; and possibly unforeseen sources such as the relic gravitational-wave radiation from the early Universe. eLISA's high signal-to-noise measurements will provide new insight into the structure and history of the Universe, and they will test general relativity in its strong-field dynamical regime
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