353 research outputs found
La publicidad engañosa en Colombia
Abogado (a)Pregrad
GW190412: measuring a black-hole recoil direction through higher-order gravitational-wave modes
General relativity predicts that gravitational waves (GWs) carry linear
momentum. Consequently, the remnant black hole of a black-hole merger can
inherit a recoil velocity or ``kick'' of crucial implications in, e.g,
black-hole formation scenarios. While the kick magnitude is determined by the
mass ratio and spins of the source, estimating its direction requires a
measurement of the two orientation angles of the source. While the orbital
inclination angle is commonly reported in GW observations, the azimuthal one
has been to date ignored. We show how the presence of more than one GW emission
mode allows constraining this angle and, consequently, determines the kick
direction in a real GW event. %We show that the higher-order mode content
GW190412 enables the determination of both these angles and, consequently, the
kick direction. We analyse the GW190412 signal, which contains higher-order
modes, with a numerical-relativity surrogate waveform model for black-hole
mergers. We find that while GW190412 is barely informative about the kick
magnitude, we can constrain its direction. This forms angles
with the orbital angular
momentum defined at a reference time before merger (being
preferentially kicked upwards), with the
line-of-sight and with the
projection of the latter onto the former, all at the credible level. We
briefly discuss the potential application of this type of measurement for
multi-messenger observations of black-hole mergers occurring in Active Galactic
Nuclei.Comment: 8 pages, 4 figure
Systematic challenges for future gravitational wave measurements of precessing binary black holes
The properties of precessing, coalescing binary black holes are presently
inferred through comparison with two approximate models of compact binary
coalescence. In this work we show these two models often disagree substantially
when binaries have modestly large spins () and modest mass ratios
(). We demonstrate these disagreements using standard figures of
merit and the parameters inferred for recent detections of binary black holes.
By comparing to numerical relativity, we confirm these disagreements reflect
systematic errors. We provide concrete examples to demonstrate that these
systematic errors can significantly impact inferences about astrophysically
significant binary parameters. For the immediate future, parameter inference
for binary black holes should be performed with multiple models (including
numerical relativity), and carefully validated by performing inference under
controlled circumstances with similar synthetic events.Comment: 12 pages, 9 figure
Impact of Bayesian Priors on the Inferred Masses of Quasi-Circular Intermediate-Mass Black Hole Binaries
Observation of gravitational waves from inspiralling binary black holes has
offered a unique opportunity to study the physical parameters of the component
black holes. To infer these parameters, Bayesian methods are employed in
conjunction with general relativistic waveform models that describe the
source's inspiral, merger, and ringdown. The results depend not only on the
accuracy of the waveform models but also on the underlying fiducial prior
distribution used for the analysis. In particular, when the pre-merger phase of
the signal is barely observable within the detectors' bandwidth, as is
currently the case with intermediate-mass black hole binary signals in
ground-based gravitational wave detectors, different prior assumptions can lead
to different interpretations. In this study, we utilise the gravitational-wave
inference library, , to evaluate the impact of mass
prior choices on the parameter estimation of intermediate-mass black hole
binary signals. While previous studies focused primarily on analysing event
data, we offer a broader, more controlled study by using simulations. Our
findings suggest that the posteriors in total mass, mass ratio and luminosity
distance are contingent on the assumed mass prior distribution used during the
inference process. This is especially true when the signal lacks sufficient
pre-merger information and/or has inadequate power in the higher-order
radiation multipoles. In conclusion, our study underscores the importance of
thoroughly investigating similarly heavy events in current detector sensitivity
using a diverse choice of priors. Absent such an approach, adopting a flat
prior on the binary's redshifted total mass and mass ratio emerges as a
reasonable choice, preventing biases in the detector-frame mass posteriors.Comment: 16 Pages, 7 figure
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