70 research outputs found
Bayesian analysis of the spin distribution of LIGO/Virgo black holes
Gravitational wave detection from binary black hole (BBH) inspirals has become routine thanks to the LIGO/Virgo interferometers. The nature of these black holes remains uncertain. We study here the spin distributions of LIGO/Virgo black holes from the first catalog GWTC-1 and the first four published BBH events from run O3. We compute the Bayes evidence for several independent priors: flat, isotropic, spin-aligned and anti-aligned. We find strong evidence for low spins in all of the cases, and significant evidence for small isotropic spins versus any other distribution. When considered as a homogeneous population of black holes, these results give support to the idea that LIGO/Virgo black holes are primordialJGB and ERM thank the Theory Division for their generous hospitality during their Sabbatical at CERN in 2018, when this work
originated. The authors acknowledge support from the Research
Project PGC2018-094773-B-C32 (MINECO-FEDER, Spain) and the
Centro de Excelencia Severo Ochoa Program, Spain SEV-2016-059
False alarms induced by Gaussian noise in gravitational wave detectors
Gaussian noise is an irreducible component of the background in gravitational wave (GW) detectors. Although stationary Gaussian noise is uncorrelated in frequencies, we show that there is an important correlation in time when looking at the matched filter signal-to-noise ratio (SNR) of a template, with a typical autocorrelation time that depends on the template and the shape of the noise power spectral density (PSD). Taking this correlation into account, we compute from first principles the false alarm rate (FAR) of a template in Gaussian noise, defined as the number of occurrences per unit time that the template's matched filter SNR goes over a threshold ρ. We find that the Gaussian FAR can be well approximated by the usual expression for uncorrelated noise, if we replace the sampling rate by an effective sampling rate that depends on the parameters of the template, the noise PSD, and the threshold ρ. This results in a minimum SNR threshold needed for a given GW trigger, if we want to keep events generated from Gaussian noise below a certain FAR. We extend the formalism to multiple detectors and to the analysis of GW events. We apply our method to the GW candidates added in the GWTC-3 catalog and discuss the possibility that GW200308_173609 and GW200322_091133 could be generated by Gaussian noise fluctuation
Analysis of the subsolar-mass black hole candidate SSM200308 from the second part of the third observing run of Advanced LIGO-Virgo
A follow-up of a subsolar black hole candidate identified in the second part
of the third observing run of the LIGO-Virgo-KAGRA collaboration is carried
out. With a search signal-to-noise ratio of and a false-alarm rate of 1
per 5 years, close to the usual thresholds for claiming a gravitational-wave
event, we cannot exclude a noise origin. A complete Bayesian parameter
estimation of this candidate, denoted SSM200308, reveals that if the signal
originates from a compact binary coalescence, the component masses are and (90%
credible intervals) with at least one component being firmly subsolar, below
the minimum mass of a neutron star. This discards the hypothesis that the
signal comes from a standard binary neutron star. The signal coherence test
between the two LIGO detectors brings support to a compact object coalescence
origin.Comment: 7 pages, 4 figures, comments welcom
El glosario como herramienta en interpretación consecutiva. Estudio de un caso práctico: la conciliación en Ruanda
En el presente artículo buscamos, basándonos en un encargo real de
interpretación consecutiva y bilateral, para las combinaciones lingüísticas
francés-español y español-francés, poner de manifiesto la importancia del
proceso de documentación previo al ejercicio de la interpretación en el ámbito
de las Relaciones Internacionales. El testimonio de Yolande Mukagasana,
superviviente del genocidio de Ruanda de 1994, es el eje temático de este
trabajo que, a partir de la recopilación y el estudio de textos paralelos, ofrece
como resultado un glosario ad hoc (francés-español y español-francés), una
herramienta de referencia para el intérprete ante cuestiones relacionadas con el
conflicto de Ruanda (1990-1994).G.I. HUM 767 (ayudas a Grupos de Investigación de la Junta de Andalucía) / Editorial Comares (colección interlingua
Particle production from symmetry breaking after inflation and leptogenesis
Recent studies suggest that the process of symmetry breaking after inflation
typically occurs very fast, within a single oscillation of the
symmetry-breaking field, due to the spinodal growth of its long-wave modes,
otherwise known as `tachyonic preheating'. We show how this sudden transition
from the false to the true vacuum can induce a significant production of
particles, bosons and fermions, coupled to the symmetry-breaking field. We find
that this new mechanism of particle production in the early Universe may have
interesting consequences for the origin of supermassive dark matter and the
generation of the observed baryon asymmetry through leptogenesis.Comment: 17 pages, 2 figures. Significantly enlarged version, including a more
detailed discussion of leptogenesis. To appear in Physics Letters
Study of gamma gamma -> W_L W_L and gamma gamma -> Z_L Z_L reactions with Chiral Lagrangians
We analyze the effects of a strongly interacting symmetry breaking sector of
the Standard Model in and reactions at TeV energies by using Chiral Lagrangians and Chiral
Perturbation Theory. We find significant deviations from the Standard Model
predictions for the differential cross sections at high invariant mass of the
gauge bosons pair. We study the experimental signals that could be obtained in
a high energy and high luminosity dedicated collider and
estimate the sensitivity that such experiments could reach to the values of the
effective lagrangian parameters.Comment: 14 pages, LaTeX, 4 figures (not included), FTUAM92/2
The Electroweak Chiral Lagrangian for the Standard Model with a Heavy Higgs
The most general chiral Lagrangian for electroweak interactions with the
complete set of invariant operators up to dimension four
is considered. The two-point and three-point functions with external gauge
fields are derived from this effective chiral Lagrangian to one-loop order in a
generic -gauge. The same set of Green's functions are paralelly studied
in the renormalizable standard model to one-loop order, in a -gauge and
in the large Higgs mass limit. An appropriate set of matching conditions
connecting the Green's functions of the two theories allows us to derive,
systematically, the values of the chiral Lagrangian coefficients corresponding
to the large Higgs mass limit of the standard model. These chiral parameters
represent the non-decoupling effects of a heavy Higgs particle and incorporate
both the leading logarithmic dependence on \mh and the next to leading
constant contributions. Some phenomenological implications are also discussed.Comment: pg.23, LaTeX, 3 figures (not included), FTUAM-93/2
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