Professor Pedro Ferreira

Abstract:

The spatial and temporal discreteness of gravitational wave sources leads to shot noise that may, in some regimes, swamp any attempts at measuring the anisotropy of the gravitational wave background. Cross-correlating a gravitational wave background map with a sufficiently dense galaxy survey can alleviate this issue, and potentially recover some of the underlying properties of the gravitational wave background. We quantify the shot noise level and we explicitly show that cross-correlating the gravitational wave background and a galaxy catalog improves the chances of a first detection of the background anisotropy with a gravitational wave observatory operating in the frequency range (10 Hz, 100 Hz), given sufficient sensitivity.

Abstract:

We construct a model for the angular power spectrum of the instrumental noise in interferometer networks mapping gravitational wave backgrounds (GWBs) as a function of detector noise properties, network configuration, and scan strategy. We use the model to calculate the noise power spectrum for current and future ground-based experiments, as well as for planned space missions. We present our results in a language similar to that used in cosmic microwave background and intensity mapping experiments, and connect the formalism with the sensitivity curves that are common lore in GWB analyses.

Abstract:

© 2020 American Physical Society. The decay timescales of the quasinormal modes of a massive scalar field have an intriguing behavior: they either grow or decay with increasing angular harmonic numbers ℓ, depending on whether the mass of the scalar field is small or large. We identify the properties of the effective potential of the scalar field that leads to this behavior and characterize it in detail. If the scalar field is nonminimally coupled, considered here, the scalar quasinormal modes will leak into the gravitational wave signal and will have decaying times that are comparable or smaller than those typical in general relativity. Hence, these modes could be detectable in the future. Finally, we find that the anomalous behavior in the decay timescales of quasinormal modes is present in a much larger class of models beyond a simple massive scalar field.

Abstract:

Our aim is to quantify the impact of systematic effects on the inference of cosmological parameters from cosmic shear. We present an end-to-end approach that introduces sources of bias in a modelled weak lensing survey on a galaxy-by-galaxy level. Residual biases are propagated through a pipeline from galaxy properties (one end) through to cosmic shear power spectra and cosmological parameter estimates (the other end), to quantify how imperfect knowledge of the pipeline changes the maximum likelihood values of dark energy parameters. We quantify the impact of an imperfect correction for charge transfer inefficiency (CTI) and modelling uncertainties of the point spread function (PSF) for Euclid, and find that the biases introduced can be corrected to acceptable levels.