arXiv subjects

Alexis Boudon

Publications and source records attributed to Alexis Boudon.

6 recordsLinked to original sources

arXiv2026

Multibanded Reduced Order Quadrature Techniques for Gravitational Wave Inference

Reduced-order quadrature (ROQ) is commonly used to accelerate parameter estimation in gravitational wave astronomy; however, constructing ROQ bases can be computationally costly, particularly for longer-duration signals. We propose a modified construction strategy based on PyROQ that accelerates this process by performing the basis search using multiband waveforms, without compromising the desired likelihood accuracy. We use this altered method to construct a set of ROQs in the sub-solar mass (SSM) range using the IMRPhenomXAS_NRTidalV3 waveform. Compared to PyROQ's standard ROQ method, we find a decrease in basis size of 20% to 30% and observe a decrease in basis construction time by 5 to 20 times, reducing from two weeks to a couple of days. We verify the bases built with this method by injecting simulated gravitational waves into LIGO-Virgo-KAGRA design noise and recovering the parameters, and we find that they preserve the likelihood accuracy and maintain consistent parameter estimation results.

gr-qc↗

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↗

arXiv2023

Supersonic friction of a black hole traversing a self-interacting scalar dark matter cloud

Black Holes (BH) traversing a dark matter cloud made out of a self-interacting scalar soliton are slowed down by two complementary effects. At low subsonic speeds, the BH accretes dark matter and this is the only source of dragging along its motion, if we neglect the backreaction of the cloud self-gravity. The situation changes at larger supersonic speeds where a shock appears. This leads to the emergence of an additional friction term, associated with the gravitational and scalar pressure interactions and with the wake behind the moving BH. This is a long distance effect that can be captured by the hydrodynamical regime of the scalar flow far away from the BH. This dynamical friction term has the same form as the celebrated Chandrasekhar collisionless result, albeit with a well-defined Coulomb logarithm and a prefactor that is smaller by a factor 2/3. The infra-red cut-off is naturally provided by the size of the scalar cloud, which is set by the scalar mass and coupling, whilst the ultra-violet behaviour corresponds to the distance from the BH where the velocity field is significantly perturbed by the BH, which is determined by pressure effects. As a result, supersonic BH are slowed down by both the accretion drag and the dynamical friction. This effect will be potentially detectable by future gravitational wave experiments as it influences the phase of the gravitational wave signal from inspiralling binaries.

astro-ph.CO↗

arXiv2023

Gravitational waves from binary black holes in a self-interacting scalar dark matter cloud

We investigate the imprints of accretion and dynamical friction on the gravitational-wave signals emitted by binary black holes embedded in a scalar dark matter cloud. As a key feature in this work, we focus on scalar fields with a repulsive self-interaction that balances against the self-gravity of the cloud. To a first approximation, the phase of the gravitational-wave signal receives extra correction terms at $-3$PN, $-4$PN and $-5.5$PN orders, relative to the prediction of vacuum general relativity, due to cloud gravity, accretion and dynamical friction. Future observations by LISA and B-DECIGO have the potential to detect these effects for a large range of scalar masses~$m_\mathrm{DM}$ and self-interaction couplings~$\lambda_4$. This would correspond to scenarios with dark matter clouds smaller than $0.1$ pc, which would be difficult to detect by other probes.

astro-ph.CO↗

arXiv2022

Subsonic accretion and dynamical friction for a black hole moving through a self-interacting scalar dark matter cloud

We investigate the flow around a black hole moving through a cloud of self-interacting scalar dark matter. We focus on the large scalar mass limit, with quartic self-interactions, and on the subsonic regime. We show how the scalar field behaves as a perfect gas of adiabatic index $\gamma_{\rm ad}=2$ at large radii while the accretion rate is governed by the relativistic regime close to the Schwarzschild radius. We obtain analytical results thanks to large-radius expansions, which are also related to the small-scale relativistic accretion rate. We find that the accretion rate is greater than for collisionless particles, by a factor $c/c_s \gg 1$, but smaller than for a perfect gas, by a factor $c_s/c \ll 1$, where $c_s$ is the speed of sound. The dynamical friction is smaller than for a perfect gas, by the same factor $c_s/c \ll 1$, and also smaller than Chandrasekhar's result for collisionless particles, by a factor $c_s/(cC)$, where $C$ is the Coulomb logarithm. It is also smaller than for fuzzy dark matter, by a factor $v_0/c \ll 1$.

astro-ph.CO↗

arXiv2020

Baryogenesis through Asymmetric Hawking Radiation from Primordial Black Holes as Dark Matter

We examine the extent to which primordial black holes (PBHs) can constitute the observed dark matter while also giving rise to the measured matter-antimatter asymmetry and account for the observed baryon abundance through asymmetric Hawking radiation generated by a derivative coupling of curvature to the baryon-lepton current. We consider both broad and monochromatic mass spectra for this purpose. For the monochromatic spectrum we find that the correct dark matter and baryon energy densities are recovered for peak masses of the spectrum of $M_{\rm pk} \geq 10^{12}$ kg whereas for the broad case the observed energy densities can be reproduced regardless of peak mass. Adopting some simplifications for the early-time expansion history as a first approximation, we also find that the measured baryon asymmetry can be recovered within an order of magnitude. We argue furthermore that the correct value of the baryon-lepton yield can in principle be retrieved for scenarios where a significant amount of the radiation is produced by PBH decay during or after reheating, as is expected when the decaying PBHs also cause reheating, or when an early matter-dominated phase is considered. We conclude from this first analysis that the model merits further investigation.

astro-ph.CO↗