5,657 research outputs found
Aligned spin neutron star-black hole mergers: a gravitational waveform amplitude model
The gravitational radiation emitted during the merger of a black hole with a
neutron star is rather similar to the radiation from the merger of two black
holes when the neutron star is not tidally disrupted. When tidal disruption
occurs, gravitational waveforms can be broadly classified in two groups,
depending on the spatial extent of the disrupted material. Extending previous
work by some of us, here we present a phenomenological model for the
gravitational waveform amplitude in the frequency domain encompassing the three
possible outcomes of the merger: no tidal disruption, "mild" and "strong" tidal
disruption. The model is calibrated to 134 general-relativistic numerical
simulations of binaries where the black hole spin is either aligned or
antialigned with the orbital angular momentum. All simulations were produced
using the SACRA code and piecewise polytropic neutron star equations of state.
The present model can be used to determine when black-hole binary waveforms are
sufficient for gravitational-wave detection, to extract information on the
equation of state from future gravitational-wave observations, to obtain more
accurate estimates of black hole-neutron star merger event rates, and to
determine the conditions under which these systems are plausible candidates as
central engines of gamma-ray bursts, macronovae and kilonovae.Comment: 15 pages, 7 figures, 1 tabl
Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors
Gravitational waves deliver information in exquisite detail about
astrophysical phenomena, among them the collision of two black holes, a system
completely invisible to the eyes of electromagnetic telescopes. Models that
predict gravitational wave signals from likely sources are crucial for the
success of this endeavor. Modeling binary black hole sources of gravitational
radiation requires solving the Eintein equations of General Relativity using
powerful computer hardware and sophisticated numerical algorithms. This
proceeding presents where we are in understanding ground-based gravitational
waves resulting from the merger of black holes and the implications of these
sources for the advent of gravitational-wave astronomy.Comment: Appeared in the Proceedings of 2014 Sant Cugat Forum on Astrophysics.
Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin:
Springer-Verlag
Synchronous Relaying Of Sensor Data
In this paper we have put forth a novel methodology to relay data obtained by
inbuilt sensors of smart phones in real time to remote database followed by
fetching of this data . Smart phones are becoming very common and they are
laced with a number of sensors that can not only be used in native applications
but can also be sent to external nodes to be used by third parties for
application and service development
Frequency-domain gravitational waves from non-precessing black-hole binaries. I. New numerical waveforms and anatomy of the signal
In this paper we discuss the anatomy of frequency-domain gravitational-wave
signals from non-precessing black-hole coalescences with the goal of
constructing accurate phenomenological waveform models. We first present new
numerical-relativity simulations for mass ratios up to 18 including spins. From
a comparison of different post-Newtonian approximants with numerical-relativity
data we select the uncalibrated SEOBNRv2 model as the most appropriate for the
purpose of constructing hybrid post-Newtonian/numerical-relativity waveforms,
and we discuss how we prepare time-domain and frequency-domain hybrid data
sets. We then use our data together with results in the literature to calibrate
simple explicit expressions for the final spin and radiated energy. Equipped
with our prediction for the final state we then develop a simple and accurate
merger-ringdown-model based on modified Lorentzians in the gravitational wave
amplitude and phase, and we discuss a simple method to represent the low
frequency signal augmenting the TaylorF2 post-Newtonian approximant with terms
corresponding to higher orders in the post-Newtonian expansion. We finally
discuss different options for modelling the small intermediate frequency regime
between inspiral and merger-ringdown. A complete phenomenological model based
on the present work is presented in a companion paper.Comment: 17 pages, 18 figures ,minor edits to tex
Fast and accurate prediction of numerical relativity waveforms from binary black hole coalescences using surrogate models
Simulating a binary black hole (BBH) coalescence by solving Einstein's
equations is computationally expensive, requiring days to months of
supercomputing time. Using reduced order modeling techniques, we construct an
accurate surrogate model, which is evaluated in a millisecond to a second, for
numerical relativity (NR) waveforms from non-spinning BBH coalescences with
mass ratios in and durations corresponding to about orbits
before merger. We assess the model's uncertainty and show that our modeling
strategy predicts NR waveforms {\em not} used for the surrogate's training with
errors nearly as small as the numerical error of the NR code. Our model
includes all spherical-harmonic waveform modes resolved by
the NR code up to We compare our surrogate model to Effective One
Body waveforms from - for advanced LIGO detectors and find
that the surrogate is always more faithful (by at least an order of magnitude
in most cases).Comment: Updated to published version, which includes a section comparing the
surrogate and effective-one-body models. The surrogate is publicly available
for download at http://www.black-holes.org/surrogates/ . 6 pages, 6 figure
Accurate inspiral-merger-ringdown gravitational waveforms for non-spinning black-hole binaries including the effect of subdominant modes
We present an analytical waveform family describing gravitational waves (GWs)
from the inspiral, merger and ringdown of non-spinning black-hole binaries
including the effect of several non-quadrupole modes [( apart from ].
We first construct spin-weighted spherical harmonics modes of hybrid waveforms
by matching numerical-relativity simulations (with mass ratio )
describing the late inspiral, merger and ringdown of the binary with
post-Newtonian/effective-one-body waveforms describing the early inspiral. An
analytical waveform family is constructed in frequency domain by modeling the
Fourier transform of the hybrid waveforms making use of analytical functions
inspired by perturbative calculations. The resulting highly accurate,
ready-to-use waveforms are highly faithful (unfaithfulness ) for observation of GWs from non-spinning black hole binaries and are
extremely inexpensive to generate.Comment: 10 pages, 5 figure
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