arXiv subjects

Josiel Mendonça Soares de Souza

Publications and source records attributed to Josiel Mendonça Soares de Souza.

5 recordsLinked to original sources

arXiv2026

Fisher and DALI posterior approximations for testing gravity with gravitational waves

We investigate the accuracy and computational efficiency of posterior approximations for gravitational-wave (GW) parameter estimation based on Fisher Matrix and its higher-order extension, the Derivative Approximation for LIkelihoods (DALI), in the context of tests of General Relativity using parameterized deviations in the inspiral waveforms (the TIGER formalism). We adopt the \texttt{IMRPhenomD} waveform and compare the exact posterior sampling to the following approximations in increasing order of complexity: the traditional Fisher Matrix, the Fisher sampling (singlet-DALI), the doublet-DALI and the triplet-DALI. We find that both singlet and doublet-DALI are significantly faster than the exact posterior by factors between 20 and 1000, depending on the inspiral SNRs -- larger gains correspond to larger SNRs. These gains are considerably larger for more complete waveforms, such as \texttt{IMRPhenomHM}. To evaluate the accuracy of the approximations, we use Jensen-Shannon divergence. We conclude that both singlet and doublet-DALI systematically improves over the standard Fisher Matrix approximation, while triplet-DALI shows large variability, limiting its practical advantage. We also introduce a code with a new implementation of Fisher and DALI analysis (Symbolic DALI, \texttt{SymDALI}) which computes derivatives symbolically via \textit{Wolfram Language}.

astro-ph.IM↗

arXiv2026

On the use of the Derivative Approximation for Likelihoods for Gravitational Wave Inference

Posterior inference on the more than a dozen parameters governing a gravitational wave (GW) event is challenging. A typical MCMC analysis can take around $100$ CPU hours, and next generation GW observatories will detect many thousands of events. Here we present a thorough comparison of the accuracy and computational cost of the Fisher Matrix, Derivative Approximation for Likelihoods (DALI) and traditional MCMC methods. We find that using DALI, which extends the traditional Fisher Matrix (FM) method to higher orders, allows for a good approximation of the posterior with a $55$ times smaller computational cost, and that the cost-benefit of the doublet-DALI is better than that of the triplet-DALI. We also show that the singlet-DALI, a hybrid MCMC-Fisher method, is much more accurate than the traditional FM and 10 times faster than the doublet-DALI. A large effort has been invested in forecasting the science case of different detector configurations, and the ability of making fast yet accurate estimations of the posteriors is an important step forward. We also introduce version \texttt{1.0} of the public \texttt{GWDALI} code, which incorporates automatic differentiation, modern waveforms and an optimized parameter decomposition.

astro-ph.IM↗

arXiv2023

Luminosity distance uncertainties from gravitational wave detections by third generation observatories

A new generation of terrestrial gravitational wave detectors is currently being planned for the next decade, and it is expected to detect most of the coalescences of compact objects in the universe with masses up to a thousand times the solar mass. Among the several possible applications of current and future detections, we focus on the impact on the measure of the luminosity distance of the sources, which is an invaluable tool for constraining the cosmic expansion history of the universe. We study two specific detector topologies, triangular and L-shaped, by investigating how topology and relative orientation of up to three detectors can minimize the uncertainty measure of the luminosity distance. While the precision in distance measurement is correlated with several geometric angles determining the source position and orientation, focusing on bright standard sirens and assuming redshift to be measured with high accuracy, we obtain analytic and numerical results for its uncertainty depending on type and number of detectors composing a network, as well as on the inclination angle of the binary plane with respect to the wave propagation direction. We also analyze the best relative location and orientation of two third generation detectors to minimize luminosity distance uncertainty, showing that prior knowledge of the inclination angle distribution plays an important role in precision recovery of luminosity distance, and that a suitably arranged network of detectors can reduce drastically the uncertainty measure, approaching the limit imposed by lensing effects intervening between source and detector at redshift $z \gtrsim 0.7$.

gr-qc↗

arXiv2023

GWDALI: A Fisher-matrix based software for gravitational wave parameter-estimation beyond Gaussian approximation

We introduce GWDALI, a new Fisher-matrix, python based software that computes likelihood gradients to forecast parameter-estimation precision of arbitrary network of terrestrial gravitational wave detectors observing compact binary coalescences. The main new feature with respect to analogous software is to assess parameter uncertainties beyond Fisher-matrix approximation, using the derivative approximation for Likelihood (DALI). The software makes optional use of the LSC algorithm library LAL and the stochastic sampling algorithm Bilby, which can be used to perform Monte-Carlo sampling of exact or approximate likelihood functions. As an example we show comparison of estimated precision measurement of selected astrophysical parameters for both the actual likelihood, and for a variety of its derivative approximations, which turn out particularly useful when the Fisher matrix is not invertible.

gr-qc↗

arXiv2022

Cosmography with Standard Sirens from the Einstein Telescope

We discuss the power of third-generation gravitational wave detectors to constrain cosmographic parameters in the case of electromagnetically bright standard sirens focusing on the specific case of the Einstein Telescope. We analyze the impact that the redshift source distribution, the number of detections and the observational error in the luminosity distance have on the inference of the first cosmographic parameters, and show that with a few hundreds detections the Hubble constant can be recovered at sub-percent level whereas the deceleration parameter at a few percent level, both with negligible bias.

gr-qc↗