4,735 research outputs found

### Radiation reaction in the 2.5PN waveform from inspiralling binaries in circular orbits

In this Comment we compute the contributions of the radiation reaction force
in the 2.5 post-Newtonian (PN) gravitational wave polarizations for compact
binaries in circular orbits. (i) We point out and correct an inconsistency in
the derivation of Arun, Blanchet, Iyer, and Qusailah. (ii) We prove that all
contributions from radiation reaction in the 2.5PN waveform are actually
negligible since they can be absorbed into a modification of the orbital phase
at the 5PN order.Comment: 7 pages, no figures, submitted to CQ

### Singular value decomposition in parametrised tests of post-Newtonian theory

Various coefficients of the 3.5 post-Newtonian (PN) phasing formula of
non-spinning compact binaries moving in circular orbits is fully characterized
by the two component masses. If two of these coefficients are independently
measured, the masses can be estimated. Future gravitational wave observations
could measure many of the 8 independent PN coefficients calculated to date.
These additional measurements can be used to test the PN predictions of the
underlying theory of gravity. Since all of these parameters are functions of
the two component masses, there is strong correlation between the parameters
when treated independently. Using Singular Value Decomposition of the Fisher
information matrix, we remove this correlations and obtain a new set of
parameters which are linear combinations of the original phasing coefficients.
We show that the new set of parameters can be estimated with significantly
improved accuracies which has implications for the ongoing efforts to implement
parametrised tests of PN theory in the data analysis pipelines.Comment: 17 pages, 6 figures, Accepted for publication in Classical and
Quantum Gravity (Matches with the published version

### Generic bounds on dipolar gravitational radiation from inspiralling compact binaries

Various alternative theories of gravity predict dipolar gravitational
radiation in addition to quadrupolar radiation. We show that gravitational wave
(GW) observations of inspiralling compact binaries can put interesting
constraints on the strengths of the dipole modes of GW polarizations. We put
forward a physically motivated gravitational waveform for dipole modes, in the
Fourier domain, in terms of two parameters: one which captures the relative
amplitude of the dipole mode with respect to the quadrupole mode ($\alpha$) and
the other a dipole term in the phase ($\beta$). We then use this two parameter
representation to discuss typical bounds on their values using GW measurements.
We obtain the expected bounds on the amplitude parameter $\alpha$ and the phase
parameter $\beta$ for Advanced LIGO (AdvLIGO) and Einstein Telescope (ET) noise
power spectral densities using Fisher information matrix. AdvLIGO and ET may at
best bound $\alpha$ to an accuracy of $\sim10^{-2}$ and $\sim10^{-3}$ and
$\beta$ to an accuracy of $\sim10^{-5}$ and $\sim10^{-6}$ respectively.Comment: Matches with the published versio

### Testing post-Newtonian theory with gravitational wave observations

The Laser Interferometric Space Antenna (LISA) will observe supermassive
black hole binary mergers with amplitude signal-to-noise ratio of several
thousands. We investigate the extent to which such observations afford
high-precision tests of Einstein's gravity. We show that LISA provides a unique
opportunity to probe the non-linear structure of post-Newtonian theory both in
the context of general relativity and its alternatives.Comment: 9 pages, 2 figure

### Precessing supermassive black hole binaries and dark energy measurements with LISA

Spin induced precessional modulations of gravitational wave signals from
supermassive black hole binaries can improve the estimation of luminosity
distance to the source by space based gravitational wave missions like the
Laser Interferometer Space Antenna (LISA). We study how this impacts the ablity
of LISA to do cosmology, specifically, to measure the dark energy equation of
state (EOS) parameter $w$. Using the $\Lambda$CDM model of cosmology, we show
that observations of precessing binaries by LISA, combined with a redshift
measurement, can improve the determination of $w$ up to an order of magnitude
with respect to the non precessing case depending on the masses, mass ratio and
the redshift.Comment: 4 pages, 4 figures, version accepted to PR

### Implications of binary black hole detections on the merger rates of double neutron stars and neutron star-black holes

We show that the inferred merger rate and chirp masses of binary black holes
(BBHs) detected by advanced LIGO (aLIGO) can be used to constrain the rate of
double neutron star (DNS) and neutron star - black hole (NSBH) mergers in the
universe. We explicitly demonstrate this by considering a set of publicly
available population synthesis models of \citet{Dominik:2012kk} and show that
if all the BBH mergers, GW150914, LVT151012, GW151226, and GW170104, observed
by aLIGO arise from isolated binary evolution, the predicted DNS merger rate
may be constrained to be $2.3-471.0$~\rate~ and that of NSBH mergers will be
constrained to $0.2-48.5$~\rate. The DNS merger rates are not constrained much
but the NSBH rates are tightened by a factor of $\sim 4$ as compared to their
previous rates. Note that these constrained DNS and NSBH rates are extremely
model dependent and are compared to the unconstrained values $2.3-472.5$ \rate~
and $0.2-218$ \rate, respectively, using the same models of
\citet{Dominik:2012kk}. These rate estimates may have implications for short
Gamma Ray Burst progenitor models assuming they are powered (solely) by DNS or
NSBH mergers. While these results are based on a set of open access population
synthesis models which may not necessarily be the representative ones, the
proposed method is very general and can be applied to any number of models
thereby yielding more realistic constraints on the DNS and NSBH merger rates
from the inferred BBH merger rate and chirp mass.Comment: 5 pages, no figures, 4 tables, v2: matches published versio

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