189 research outputs found
Parameter estimation on gravitational waves from multiple coalescing binaries
Future ground-based and space-borne interferometric gravitational-wave
detectors may capture between tens and thousands of binary coalescence events
per year. There is a significant and growing body of work on the estimation of
astrophysically relevant parameters, such as masses and spins, from the
gravitational-wave signature of a single event. This paper introduces a robust
Bayesian framework for combining the parameter estimates for multiple events
into a parameter distribution of the underlying event population. The framework
can be readily deployed as a rapid post-processing tool
Use of the MultiNest algorithm for gravitational wave data analysis
We describe an application of the MultiNest algorithm to gravitational wave
data analysis. MultiNest is a multimodal nested sampling algorithm designed to
efficiently evaluate the Bayesian evidence and return posterior probability
densities for likelihood surfaces containing multiple secondary modes. The
algorithm employs a set of live points which are updated by partitioning the
set into multiple overlapping ellipsoids and sampling uniformly from within
them. This set of live points climbs up the likelihood surface through nested
iso-likelihood contours and the evidence and posterior distributions can be
recovered from the point set evolution. The algorithm is model-independent in
the sense that the specific problem being tackled enters only through the
likelihood computation, and does not change how the live point set is updated.
In this paper, we consider the use of the algorithm for gravitational wave data
analysis by searching a simulated LISA data set containing two non-spinning
supermassive black hole binary signals. The algorithm is able to rapidly
identify all the modes of the solution and recover the true parameters of the
sources to high precision.Comment: 18 pages, 4 figures, submitted to Class. Quantum Grav; v2 includes
various changes in light of referee's comment
Cosmology with the lights off: Standard sirens in the Einstein Telescope era
We explore the prospects for constraining cosmology using gravitational-wave
(GW) observations of neutron-star binaries by the proposed Einstein Telescope
(ET), exploiting the narrowness of the neutron-star mass function. Double
neutron-star (DNS) binaries are expected to be one of the first sources
detected after "first-light" of Advanced LIGO and are expected to be detected
at a rate of a few tens per year in the advanced era. However the proposed ET
could catalog tens of thousands per year. Combining the measured source
redshift distributions with GW-network distance determinations will permit not
only the precision measurement of background cosmological parameters, but will
provide an insight into the astrophysical properties of these DNS systems. Of
particular interest will be to probe the distribution of delay times between
DNS-binary creation and subsequent merger, as well as the evolution of the
star-formation rate density within ET's detection horizon. Keeping H_0,
\Omega_{m,0} and \Omega_{\Lambda,0} fixed and investigating the precision with
which the dark-energy equation-of-state parameters could be recovered, we found
that with 10^5 detected DNS binaries we could constrain these parameters to an
accuracy similar to forecasted constraints from future CMB+BAO+SNIa
measurements. Furthermore, modeling the merger delay-time distribution as a
power-law, and the star-formation rate (SFR) density as a parametrized version
of the Porciani and Madau SF2 model, we find that the associated astrophysical
parameters are constrained to within ~ 10%. All parameter precisions scaled as
1/sqrt(N), where N is the number of cataloged detections. We also investigated
how precisions varied with the intrinsic underlying properties of the Universe
and with the distance reach of the network (which may be affected by the
low-frequency cutoff of the detector).Comment: 24 pages, 11 figures, 6 tables. Minor changes to reflect published
version. References updated and correcte
Pure Gravitational Wave Estimation of Hubble's Constant using Neutron Star-Black Hole Mergers
Here we show how can be derived purely from the gravitational waves
(GW) of neutron star-black hole (NSBH) mergers. This new method provides an
estimate of spanning the redshift range, with current GW
sensitivity and without the need for any afterglow detection. We utilise the
inherently tight neutron star mass function together with the NSBH waveform
amplitude and frequency to estimate distance and redshift respectively, thereby
obtaining statistically. Our first estimate is km
s Mpc for the secure NSBH events GW190426 and GW200115. We
forecast that soon, with 10 more such NSBH events we can reach competitive
precision of .Comment: 13 pages, 10 figure
Bayesian inference for compact binary coalescences with BILBY:Validation and application to the first LIGO-Virgo gravitational-wave transient catalogue
Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational-wave transients (GWTC-1) contains eleven signals from black hole and neutron star binaries, the number of observations is increasing rapidly as detector sensitivity improves. To extract information from the observed signals, it is imperative to have fast, flexible, and scalable inference techniques. In a previous paper, we introduced BILBY: a modular and user-friendly Bayesian inference library adapted to address the needs of gravitational-wave inference. In this work, we demonstrate that BILBY produces reliable results for simulated gravitational-wave signals from compact binary mergers, and verify that it accurately reproduces results reported for the eleven GWTC-1 signals. Additionally, we provide configuration and output files for all analyses to allow for easy reproduction, modification, and future use. This work establishes that BILBY is primed and ready to analyse the rapidly growing population of compact binary coalescence gravitational-wave signals
Binary Neutron Star Mergers: Gravitational-wave Measurements of Their Parameters and the Nuclear Equation of State
Since making the first direct detection of gravitational waves in 2015, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) together with the Virgo observatory has detected an additional 51 confirmed signals from binary mergers. Two of these signals, GW170817 and GW190425, were identified as binary neutron star mergers. As detector sensitivity improves we expect to see many more binary neutron star merger events, both from future observing runs of the LIGO-Virgo network and from planned third-generation detectors. These new detections will provide an exquisite look at the nature of these systems and of neutron stars themselves. This thesis describes how gravitational-wave observations of neutron star mergers can be used to measure the properties of the binary systems and the fundamental physics of neutron stars. We use multimessenger observations of GW170817 to measure its viewing angle, which is important to understand the engine driving the electromagnetic counterpart to the gravitational-wave signal. We describe a new implementation of a fast likelihood model for gravitational-wave parameter estimation. We demonstrate that this likelihood allows analysis of binary neutron star signals to be performed quickly enough to inform strategies for electromagnetic follow-up observations. We measure the tidal deformabilities and radii of the neutron stars in GW170817, imposing a physical constraint to require that both neutron stars obey a common nuclear equation of state. We assess the future prospects for measuring the nuclear equation of state with the LIGO-Virgo network and with the planned third-generation detector, Cosmic Explorer
A detection pipeline for galactic binaries in LISA data
The Galaxy is suspected to contain hundreds of millions of binary white dwarf
systems, a large fraction of which will have sufficiently small orbital period
to emit gravitational radiation in band for space-based gravitational wave
detectors such as the Laser Interferometer Space Antenna (LISA). LISA's main
science goal is the detection of cosmological events (supermassive black hole
mergers, etc.) however the gravitational signal from the galaxy will be the
dominant contribution to the data -- including instrumental noise -- over
approximately two decades in frequency. The catalogue of detectable binary
systems will serve as an unparalleled means of studying the Galaxy.
Furthermore, to maximize the scientific return from the mission, the data must
be "cleansed" of the galactic foreground. We will present an algorithm that can
accurately resolve and subtract >10000 of these sources from simulated data
supplied by the Mock LISA Data Challenge Task Force. Using the time evolution
of the gravitational wave frequency, we will reconstruct the position of the
recovered binaries and show how LISA will sample the entire compact binary
population in the Galaxy.Comment: 12 pages, 8 figure
The Missing Link: Bayesian Detection and Measurement of Intermediate-Mass Black-Hole Binaries
We perform Bayesian analysis of gravitational-wave signals from non-spinning,
intermediate-mass black-hole binaries (IMBHBs) with observed total mass,
, from to and
mass ratio 1\mbox{--}4 using advanced LIGO and Virgo detectors. We employ
inspiral-merger-ringdown waveform models based on the effective-one-body
formalism and include subleading modes of radiation beyond the leading
mode. The presence of subleading modes increases signal power for inclined
binaries and allows for improved accuracy and precision in measurements of the
masses as well as breaking of extrinsic parameter degeneracies. For low total
masses, , the observed chirp
mass ( being the
symmetric mass ratio) is better measured. In contrast, as increasing power
comes from merger and ringdown, we find that the total mass
has better relative precision than . Indeed, at high
(), the signal resembles a
burst and the measurement thus extracts the dominant frequency of the signal
that depends on . Depending on the binary's inclination, at
signal-to-noise ratio (SNR) of , uncertainties in can be
as large as \sim 20 \mbox{--}25\% while uncertainties in are \sim 50 \mbox{--}60\% in binaries with unequal masses (those
numbers become versus in more symmetric binaries).
Although large, those uncertainties will establish the existence of IMBHs. Our
results show that gravitational-wave observations can offer a unique tool to
observe and understand the formation, evolution and demographics of IMBHs,
which are difficult to observe in the electromagnetic window. (abridged)Comment: 17 pages, 9 figures, 2 tables; updated to reflect published versio
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