arXiv subjects

Jean-François Coupechoux

Publications and source records attributed to Jean-François Coupechoux.

3 recordsLinked to original sources

arXiv2025

A Realistic Projection for Constraining Neutron Star Equation of State with the LIGO-Virgo-KAGRA Detector Network in the A+ Era

The LIGO-Virgo-KAGRA network in the upcoming A+ era with upgrades of both Advanced LIGO and Advanced Virgo will enable more frequent and precise observations of binary neutron star (BNS) mergers, improving constraints on the neutron star equation of state (EOS). In this study, we applied reduced order quadrature techniques for full parameter estimation of 3,000 simulated gravitational wave signals from BNS mergers at A+ sensitivity following three EOS models: HQC18, SLY230A, and MPA1. We found that tidal deformability tends to be overestimated at higher mass and underestimated at lower mass. We postprocessed the parameter estimation results to present our EOS recovery accuracies, identify biases within EOS constraints and their causes, and quantify the needed corrections.

gr-qc↗

arXiv2020

Black hole mergers, gravitational waves and scaling relations

Observations of gravitational waves provide new opportunities to study our Universe. In particular, mergers of stellar black holes are the main targets of the current gravitational wave experiments. In order to make accurate predictions, it is however necessary to simulate the mergers in numerical general relativity, which requires high performance computing. While scaling relations are used to rescale simulations for very massive black holes, primordial black holes have specific properties which can invalidate the rescaling. Similarly black holes in theories beyond Einstein's relativity can have different scaling properties. In this article, we consider scaling relations for the most general cases of primordial black holes, such as charged and spinned black holes, and study the effects of the cosmological expansion and of Hawking evaporation. We also consider more exotic black hole models and derive the corresponding scaling relations, which can be compared to the observations in order to identify the underlying black hole model and can be used to rescale the numerical simulations of exotic black hole mergers.

gr-qc↗

arXiv2016

Phonon spectrum and correlations in a transonic flow of an atomic Bose gas

Motivated by a recent experiment of J.~Steinhauer, we reconsider the spectrum and the correlations of the phonons spontaneously emitted in stationary transonic flows. The latter are described by "waterfall" configurations which form a one-parameter family of stable flows. For parameters close to their experimental values, in spite of high gradients near the sonic horizon, the spectrum is accurately planckian in the relevant frequency domain, where the temperature differs from the relativistic prediction by less than $10 \%$. We then study the density correlations across the horizon and the non-separable character of the final state. We show that the relativistic expressions provide accurate approximations when the initial temperature is not too high. We also show that the phases of the scattering coefficients introduce a finite shift of the location of the correlations which was so far overlooked. This shift is due to the asymmetry of the flow across the horizon, and persists in the dispersion-less regime. Finally we show how the formation of the sonic horizon modifies both local and non-local density correlations.

cond-mat.quant-gas↗