Analytical template for gravitational-wave echoes: signal characterization and prospects of detection with current and future interferometers

Gravitational-wave echoes in the post-merger ringdown phase are under intense scrutiny as probes of near-horizon quantum structures and as signatures of exotic states of matter in ultracompact stars. We present an analytical template that describes the ringdown and the echo signal for nonspinning objects in terms of two physical parameters: the reflectivity and the redshift at the surface of the object. We characterize the properties of the template and adopt it in a preliminary parameter estimation with current (aLIGO) and future (Cosmic Explorer, Einstein Telescope, LISA) gravitational-wave detectors. For fixed signal-to-noise ratio in the post-merger phase, the constraints on the model parameters depend only mildly on the details of the detector sensitivity curve, but depend strongly on the reflectivity. Our analysis suggests that it might be possible to detect or rule out Planckian corrections at the horizon scale for perfectly-reflecting ultracompact objects at $5\sigma$ confidence level with Advanced LIGO/Virgo. On the other hand, signal-to-noise ratios in the ringdown phase equal to $\approx 100$ (as achievable with future interferometers) might allow us to probe near-horizon quantum structures with reflectivity $\gtrsim30\%$ ($\gtrsim85\%$) at $2\sigma$ ($3\sigma$) level.Comment: v3: 13+4 pages, 11 figures, 4 appendices; matches the PRD version with a new plot and extended results. v2 (submitted version): 12 pages + 4 appendices; 9 figures. Further discussion and new appendix with template for localized sources at generic position. Template and waveforms available at https://www.darkgra.org/gw-echo-catalogue.htm

Impact of transforming to conformal Fermi coordinates on quasisingle field non-Gaussianity

In general relativity predictions for observable quantities can be expressed in a coordinate independent way. Nonetheless it may be inconvenient to do so. Using a particular frame may be the easiest way to connect theoretical predictions to measurable quantities. For the cosmological curvature bispectrum such frame is described by the Conformal Fermi Coordinates. In single field inflation it was shown that going to this frame cancels the squeezed limit of the density perturbation bispectrum calculated in Global Coordinates. We explore this issue in quasi single field inflation when the curvaton mass and the curvaton-inflaton mixing are small. In this case, the contribution to the bispectrum from the coordinate transformation to Conformal Fermi Coordinates is of the same order as that from the inflaton-curvaton interaction term but does not cancel it

Impact of transforming to Conformal Fermi Coordinates on Quasi-Single Field Non-Gaussianity

In general relativity predictions for observable quantities can be expressed in a coordinate independent way. Nonetheless it may be inconvenient to do so. Using a particular frame may be the easiest way to connect theoretical predictions to measurable quantities. For the cosmological curvature bispectrum such frame is described by the Conformal Fermi Coordinates. In single field inflation it was shown that going to this frame cancels the squeezed limit of the density perturbation bispectrum calculated in Global Coordinates. We explore this issue in quasi single field inflation when the curvaton mass and the curvaton-inflaton mixing are small. In this case, the contribution to the bispectrum from the coordinate transformation to Conformal Fermi Coordinates is of the same order as that from the inflaton-curvaton interaction term but does not cancel it.Comment: 13 pages, 2 figure

Regularization Scheme Dependence of the Counterterms in the Galaxy Bias Expansion

In this paper we explore how different regularization prescriptions affect the counterterms in the renormalization of the galaxy bias expansion. We work in the context of primordial local non-Gaussianity including non-linear gravitational evolution. We carry out the one-loop renormalization of the field $\delta_\rho^2$ (i.e. the square of the matter overdensity field) up to third order in gravitational evolution. Three regularization schemes are considered and their impact on the values of the counterterms is studied. We explicitly verify that the coefficients of the non-boost invariant operators are regularization scheme independent.Comment: 17 pages, 10 figures. Corrected few typos. The article is now updated to match the journal versio

Analytical model for gravitational-wave echoes from spinning remnants

Gravitational-wave echoes in the postmerger signal of a binary coalescence are predicted in various scenarios, including near-horizon quantum structures, exotic states of matter in ultracompact stars, and certain deviations from general relativity. The amplitude and frequency of each echo is modulated by the photon-sphere barrier of the remnant, which acts as a spin- and frequency-dependent high-pass filter, decreasing the frequency content of each subsequent echo. Furthermore, a major fraction of the energy of the echo signal is contained in low-frequency resonances corresponding to the quasinormal modes of the remnant. Motivated by these features, in this work we provide an analytical gravitational-wave template in the low-frequency approximation describing the postmerger ringdown and the echo signal of a spinning ultracompact object. Besides the standard ringdown parameters, the template is parametrized in terms of only two physical quantities: the reflectivity coefficient and the compactness of the remnant. We discuss novel effects related to the spin and to the complex reflectivity, such as a more involved modulation of subsequent echoes, the mixing of two polarizations, and the ergoregion instability in the case of perfectly reflecting spinning remnants. Finally, we compute the errors in the estimation of the template parameters with current and future gravitational-wave detectors using a Fisher matrix framework. Our analysis suggests that models with almost perfect reflectivity can be excluded/detected with current instruments, whereas probing values of the reflectivity smaller than 80% at the 3σ confidence level requires future detectors (Einstein Telescope, Cosmic Explorer, LISA). The template developed in this work can easily be implemented to perform a matched-filter based search for echoes and to constrain models of exotic compact objects

Finite Naturalness and Quark-Lepton Unification

We study the implications of finite naturalness in Pati-Salam models where SU(3)c is embedded in SU(4). For the minimal realization at low scale of quark-lepton unification, which employs the inverse seesaw for neutrino masses, we find that radiative corrections to the Higgs boson mass are at least $\delta m_h^2/m_h^2 \sim {\cal O}(10^3)$. We find that the one-loop contributions to the Higgs mass are suppressed by four powers of the hypercharge gauge coupling. Naively, the two-loop contributions involving the heavy vector bosons are large. We find that for the vector leptoquarks these two-loop corrections cancel when the Dirac Yukawa couplings for neutrinos are equal to the up-type quark Yukawa couplings as predicted in the minimal theory for quark-lepton unification. We show that the two-loop corrections to the Higgs mass involving the new heavy neutral gauge boson are suppressed. We mention a way to relax the lower bound on the vector leptoquark mass and have $\delta m_h^2/m_h^2 \sim {\cal O}(1)$.Comment: 8 page

Analytical model for gravitational-wave echoes from spinning remnants

Gravitational-wave echoes in the postmerger signal of a binary coalescence are predicted in various scenarios, including near-horizon quantum structures, exotic states of matter in ultracompact stars, and certain deviations from general relativity. The amplitude and frequency of each echo is modulated by the photon-sphere barrier of the remnant, which acts as a spin- and frequency-dependent high-pass filter, decreasing the frequency content of each subsequent echo. Furthermore, a major fraction of the energy of the echo signal is contained in low-frequency resonances corresponding to the quasinormal modes of the remnant. Motivated by these features, in this work we provide an analytical gravitational-wave template in the low-frequency approximation describing the postmerger ringdown and the echo signal of a spinning ultracompact object. Besides the standard ringdown parameters, the template is parametrized in terms of only two physical quantities: the reflectivity coefficient and the compactness of the remnant. We discuss novel effects related to the spin and to the complex reflectivity, such as a more involved modulation of subsequent echoes, the mixing of two polarizations, and the ergoregion instability in the case of perfectly reflecting spinning remnants. Finally, we compute the errors in the estimation of the template parameters with current and future gravitational-wave detectors using a Fisher matrix framework. Our analysis suggests that models with almost perfect reflectivity can be excluded/detected with current instruments, whereas probing values of the reflectivity smaller than 80% at the 3σ confidence level requires future detectors (Einstein Telescope, Cosmic Explorer, LISA). The template developed in this work can easily be implemented to perform a matched-filter based search for echoes and to constrain models of exotic compact objects

Ultra-deep Large Binocular Camera U-band Imaging of the GOODS-North Field: Depth vs. Resolution

We present a study of the trade-off between depth and resolution using a large number of U-band imaging observations in the GOODS-North field (Giavalisco et al. 2004) from the Large Binocular Camera (LBC) on the Large Binocular Telescope (LBT). Having acquired over 30 hours of data (315 images with 5-6 mins exposures), we generated multiple image mosaics, starting with the best atmospheric seeing images (FWHM $\lesssim$0.8"), which constitute $\sim$10% of the total data set. For subsequent mosaics, we added in data with larger seeing values until the final, deepest mosaic included all images with FWHM $\lesssim$1.8" ($\sim$94% of the total data set). From the mosaics, we made object catalogs to compare the optimal-resolution, yet shallower image to the lower-resolution but deeper image. We show that the number counts for both images are $\sim$90% complete to $U_{AB}$ $\lesssim26$. Fainter than $U_{AB}$$\sim$ 27, the object counts from the optimal-resolution image start to drop-off dramatically (90% between $U_{AB}$ = 27 and 28 mag), while the deepest image with better surface-brightness sensitivity ($\mu^{AB}_{U}$$\lesssim$ 32 mag arcsec$^{-2}$) show a more gradual drop (10% between $U_{AB}$ $\simeq$ 27 and 28 mag). For the brightest galaxies within the GOODS-N field, structure and clumpy features within the galaxies are more prominent in the optimal-resolution image compared to the deeper mosaics. Finally, we find - for 220 brighter galaxies with $U_{AB}$$\lesssim$ 24 mag - only marginal differences in total flux between the optimal-resolution and lower-resolution light-profiles to $\mu^{AB}_{U}$$\lesssim$ 32 mag arcsec$^{-2}$. In only 10% of the cases are the total-flux differences larger than 0.5 mag. This helps constrain how much flux can be missed from galaxy outskirts, which is important for studies of the Extragalactic Background Light.Comment: 24 pages, 14 figures, submitted to PASP, comments welcom

Escala de avaliação da qualidade de vida por meio da Teoria da Resposta ao Item

O objetivo deste estudo foi criar uma escala para medir a qualidade de vida (QV) por meio da Teoria da Resposta ao Item (TRI). Para isso, foram coletados dados de 940 profissionais de Educação Física (PEF) registrados no Conselho Regional de Educação Física de Santa Catarina (CREF3-SC) em 2012, por meio do questionário WHOQOL-Bref. Para o tratamento dos dados, foi utilizado os recursos da TRI, com base no modelo de resposta gradual (MRG). Os resultados possibilitaram a criação de uma escala com 26 itens, com quatro categorias ordinais, em cinco níveis da escala. Na amostra dos PEF, os itens mais comuns na QV foram aqueles associados à dor física, à necessidade de tratamento médico e à capacidade de locomoção. Os itens mais incomuns foram aqueles associados às questões do ambiente físico, acesso aos serviços de saúde e questão financeira.  O WHOQOL-Bref e o MRG mostraram-se adequados e forneceram recursos necessários à construção da escala de qualidade de vida