64 research outputs found
LISA observations of supermassive black holes: parameter estimation using full post-Newtonian inspiral waveforms
We study parameter estimation of supermassive black hole binary systems in
the final stage of inspiral using the full post-Newtonian gravitational
waveforms. We restrict our analysis to systems in circular orbit with
negligible spins, in the mass range 10^8\Ms-10^5\Ms, and compare the results
with those arising from the commonly used restricted post-Newtonian
approximation. The conclusions of this work are particularly important with
regard to the astrophysical reach of future LISA measurements. Our analysis
clearly shows that modeling the inspiral with the full post-Newtonian waveform,
not only extends the reach to higher mass systems, but also improves in general
the parameter estimation. In particular, there are remarkable improvements in
angular resolution and distance measurement for systems with a total mass
higher than 5\times10^6\Ms, as well as a large improvement in the mass
determination.Comment: Final version. Accepted for publication in Phys. Rev.
The Adaptive Transient Hough method for long-duration gravitational wave transients
This paper describes a new semi-coherent method to search for transient
gravitational waves of intermediate duration (hours to days). In order to
search for newborn isolated neutron stars with their possibly very rapid
spin-down, we model the frequency evolution as a power law. The search uses
short Fourier transforms from the output of ground-based gravitational wave
detectors and applies a weighted Hough transform, also taking into account the
signal's amplitude evolution. We present the technical details for implementing
the algorithm, its statistical properties, and a sensitivity estimate. A first
example application of this method was in the search for GW170817 post-merger
signals, and we verify the estimated sensitivity with simulated signals for
this case.Comment: 13 pages, 14 figure
El nacimiento de la astronomía de ondas gravitacionales
Los últimos tres años han sido testigos del nacimiento de la astronomía de ondas gravitacionales. Esta nueva era de la astronomía empezó de repente en septiembre de 2015 con la primera detección de una fusión de binarias de agujeros negros situados a 1.300 millones de años luz de distancia. Este descubrimiento causó un revuelo en la comunidad científica, no solo porque confirmaba una importante predicción de la teoría de la relatividad general de Albert Einstein de 1915, sino también por el impacto en el campo de la astronomía de este evento cósmico nunca antes observado. La importancia de este hallazgo dio pie a la concesión de los más prestigiosos premios científicos, incluido el Premio Nobel en Física en 2017. Otro descubrimiento más reciente, el de una fusión de un sistema binario de estrellas de neutrones, detectada conjuntamente por los detectores LIGO y Virgo, seguido de una explosión de rayos gamma y una kilonova, han reforzado la emoción de esta nueva era, en la que pronto esperamos ver otro tipo de fuentes y hacer astronomía de alta precisió
Matched-filter study and energy budget suggest no detectable gravitational-wave 'extended emission' from GW170817
Van Putten & Della Valle (2018) have reported a possible detection of
gravitational-wave 'extended emission' from a neutron star remnant of GW170817.
Starting from the time-frequency evolution and total emitted energy of their
reported candidate, we show that such an emission is not compatible with the
current understanding of neutron stars. We explore the additional required
physical assumptions to make a full waveform model, for example, taking the
optimistic emission from a spining-down neutron star with fixed quadrupolar
deformation, and study whether even an ideal single-template matched-filter
analysis could detect an ideal, fully phase-coherent signal. We find that even
in the most optimistic case an increase in energy and extreme parameters would
be required for a confident detection with LIGO sensitivity as of 2018-08-17.
The argument also holds for other waveform models following a similar
time-frequency track and overall energy budget. Single-template matched
filtering on the LIGO data around GW170817, and on data with added simulated
signals, verifies the expected sensitivity scaling and the overall statistical
expectation.Comment: 9 pages, 6 figures, updated version as accepted by MNRA
Infinite Kinematic Self-Similarity and Perfect Fluid Spacetimes
Perfect fluid spacetimes admitting a kinematic self-similarity of infinite
type are investigated. In the case of plane, spherically or hyperbolically
symmetric space-times the field equations reduce to a system of autonomous
ordinary differential equations. The qualitative properties of solutions of
this system of equations, and in particular their asymptotic behavior, are
studied. Special cases, including some of the invariant sets and the geodesic
case, are examined in detail and the exact solutions are provided. The class of
solutions exhibiting physical self-similarity are found to play an important
role in describing the asymptotic behavior of the infinite kinematic
self-similar models.Comment: 38 pages, 6 figures. Accepted for publication in General Relativity &
Gravitatio
A veto for continuous gravitational wave searches
vetoes are commonly used in searching for gravitational waves, in
particular for broad-band signals, but they can also be applied to narrow-band
continuous wave signals, such as those expected from rapidly rotating neutron
stars. In this paper we present a veto adapted to the Hough transform
searches for continuous gravitational wave signals; we characterize the
-significance plane for different frequency bands; and discuss the
expected performance of this veto in LIGO analysis.Comment: Final version, 12th Gravitational Waves Data Analysis Worksho
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