A5036719760- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Relativity and Gravitational Theory
- Black Holes and Theoretical Physics
- Dark Matter and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Noncommutative and Quantum Gravity Theories
- Solar and Space Plasma Dynamics
- Quantum chaos and dynamical systems
- Quantum Mechanics and Non-Hermitian Physics
- Experimental and Theoretical Physics Studies
- Semiconductor Quantum Structures and Devices
- Photonic and Optical Devices
- Phase-change materials and chalcogenides
- Astrophysics and Star Formation Studies
- History and advancements in chemistry
- Quantum Dots Synthesis And Properties
- Radio Astronomy Observations and Technology
Laboratoire Univers et Particules de Montpellier
2024-2025
Centre National de la Recherche Scientifique
2013-2024
CEA Paris-Saclay
2022-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2022-2024
Institut de Physique Théorique
2022-2024
Université Paris-Saclay
2022-2023
Universidad Autónoma de Madrid
2020-2022
Consejo Superior de Investigaciones Científicas
2022
University of Geneva
2017-2020
University of Cape Town
2016-2017
The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about fundamental theory of nature at play in extreme gravity regime, where gravitational interaction is both strong and dynamical. In this white paper, Fundamental Physics Working Group LISA Consortium summarizes current topics physics observations GWs can be expected provide key input. We briefest reviews then delineate avenues for future research directions discuss connections between working group, other...
In the standard cosmological framework, Hubble diagram is interpreted by assuming that light emitted candles propagates in a spatially homogeneous and isotropic spacetime. However, from ``point sources''---such as supernovae---probes Universe on scales where homogeneity principle no longer valid. Inhomogeneities are expected to induce bias dispersion of diagram. This investigated considering Swiss-cheese model, which (1) an exact solution Einstein field equations, (2) strongly inhomogeneous...
The equivalence principle, that is one of the main pillars general relativity, very well tested in Solar system; however, its validity more uncertain on cosmological scales, or when dark matter concerned. This article shows relativistic effects large-scale structure can be used to directly test whether satisfies Euler's equation, i.e. free fall characterised by geodesic motion, just like baryons and light. After having proposed a parametrisation for deviations from we perform Fisher-matrix...
The Hubble diagram is one of the cornerstones observational cosmology. It usually analysed assuming that, on average, underlying relation between magnitude and redshift matches prediction a Friedmann-Lema\^itre-Robertson-Walker model. However, inhomogeneity Universe generically biases these observables, mainly due to peculiar velocities gravitational lensing, in way that depends notion average used theoretical calculations. In this article, we carefully derive which corresponds observation...
Abstract Primordial black holes (PBHs) are compact objects proposed to have formed in the early Universe from collapse of small-scale over-densities. Their existence may be detected observation gravitational waves (GWs) emitted by PBH mergers, if signals can distinguished those produced merging astrophysical holes. In this work, we forecast capability Einstein Telescope, a third-generation GW observatory, identify and measure abundance subdominant population distant PBHs, using difference...
The recent analysis of the Planck results reveals a tension between best fits for (Ω(m0), H(0)) derived from cosmic microwave background or baryonic acoustic oscillations on one hand, and Hubble diagram other hand. These observations probe Universe very different scales since they involve light beams angular sizes; hence, them may indicate that should not be interpreted same way. More precisely, this Letter questions accuracy using only (perturbed) Friedmann-Lemaître geometry to interpret...
Various extensions of standard inflationary models have been proposed recently by adding vector fields. Because they are generally motivated large-scale anomalies, and the possibility statistical anisotropy primordial fluctuations, such require to introduce non-standard couplings between fields on one hand, either gravity or scalar other hand. In this article, we study involving a field coupled field. We derive restrictive necessary conditions for these be both stable (Hamiltonian bounded...
This article proposes a comprehensive analysis of light propagation in an anisotropic and spatially homogeneous Bianchi I universe. After recalling that null geodesics are easily determined such spacetime, we derive the expressions redshift direction drifts sources; by solving analytically Sachs equation, then obtain explicit expression Jacobi matrix describing narrow beams. As by-product, recover old formula Saunders for angular diameter distance but our derivation goes further since it...
Standard sirens have been proposed as probes of alternative theories gravity, such Horndeski models. Hitherto, all studies conducted on a homogeneous-isotropic cosmological background, which is unable to consistently account for realistic distributions matter, and inhomogeneities in the scalar field. Yet, latter are essential screening mechanisms. In this article, we comprehensively analyze propagation gravitational waves an arbitrary background spacetime We restrict our study class...
While most strong-gravitational-lensing systems may be roughly modelled by a single massive object between the source and observer, in details all structures near light path contribute to observed images. These additional contributions, known as line-of-sight effects, are non-negligible practice. This article proposes new theoretical framework model together with very promising applications at interface of weak strong lensing. Our approach relies on dominant-lens approximation, where one...
In dark-energy models where a scalar field is nonminimally coupled to the spacetime geometry, gravitational waves are expected be supplemented with mode. Such may interact standard tensor waves, thereby affecting their observed amplitude and polarization. Understanding role of thus essential in order design reliable gravitational-wave probes dark energy gravity beyond general relativity. this article, we thoroughly investigate propagation subset Horndeski theories which propagate at speed...
In view of interpreting the cosmological observations precisely, especially when they involve narrow light beams, it is crucial to understand how propagates in our statistically homogeneous, clumpy, Universe. Among various approaches tackle this issue, Swiss-cheese models propose an inhomogeneous spacetime geometry which exact solution Einstein's equation, while Dyer-Roeder approximation deals with inhomogeneity effective way. article, we demonstrate that distance-redshift relation a certain...
The standard model of cosmology is based on the hypothesis that Universe spatially homogeneous and isotropic. When interpreting most observations, this cosmological principle applied stricto sensu: light emitted by distant sources assumed to propagate through a Friedmann-Lemaître spacetime. main goal present thesis was evaluate how reliable assumption is, especially when small scales are at stake. After having reviewed laws geometric optics in curved spacetime, interpretation observables,...
Line-of-sight effects in strong gravitational lensing have long been treated as a nuisance. However, it was recently proposed that the line-of-sight shear could be cosmological observable its own right, if is not degenerate with lens model parameters. We firstly demonstrate can accurately measured from simple simulated image percent precision. then extend our analysis to more complex images and stress test recovery of when using deficient fitting models, finding escapes degeneracies...
The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation and observations in cosmological models. In this article, we propose detailed, pedagogical, rigorous introduction coordinate system, explore its gauge degrees of freedom, emphasize interest when geometric optics is at stake. We then apply the GLC formalism homogeneous anisotropic Bianchi I cosmology. More than simple illustration, application (i) allows us show that Weinberg conjecture according which...
The LIGO discoveries have rekindled suggestions that primordial black holes (BHs) may constitute part to all of the dark matter (DM) in Universe. Such came from 1) observed merger rate BHs, 2) their unusual masses, 3) low/zero spins, and 4) also independently uncovered cosmic infrared background (CIB) fluctuations signal high amplitude coherence with unresolved X-ray (CXB). Here we summarize prospects resolve this important issue electromagnetic observations using instruments tools expected...
The standard theory of weak gravitational lensing relies on the infinitesimal light beam approximation. In this context, images are distorted by convergence and shear, respective sources which unphysically depend resolution distribution matter---the so-called Ricci-Weyl problem. Letter, we propose a strong-lensing-inspired formalism to describe finite beams. We address problem showing explicitly that is caused matter enclosed beam, regardless its distribution. Furthermore, shear turns out be...
On small scales the observable Universe is highly inhomogeneous, with galaxies and clusters forming a complex web of voids filaments. The optical properties such configurations can be quite different from perfectly smooth Friedmann-Lema\^itre-Robertson-Walker (FLRW) solutions that are frequently used in cosmology, must well understood if we to make precise inferences about fundamental physics cosmological observations. We investigate this problem by calculating redshifts luminosity distances...
The standard cosmological model is based on the fundamental assumptions of a spatially homogeneous and isotropic universe large scales. An observational detection violation these at any redshift would immediately indicate presence new physics. We quantify ability Euclid mission, together with contemporary surveys, to improve current sensitivity null tests canonical constant $\Lambda$ cold dark matter (LCDM) in range $0<z<1.8$. considered both currently available data simulated external...
The standard theory of weak gravitational lensing relies on the approximation that light beams are infinitesimal. Our recent work showed finite size sources, and associated beams, can cause nonperturbative corrections to weak-lensing convergence shear. This article thoroughly investigates these in a realistic cosmological model. continuous transition from infinitesimal is understood, reveals previous results overestimated finite-beam effects due simplistic assumptions distribution matter...
The weak equivalence principle is one of the cornerstone general relativity. Its validity has been tested with impressive precision in Solar System, experiments involving baryonic matter and light. However, on cosmological scales when dark concerned, this still unknown. In paper we construct a null test that probes for matter. Our strong advantage it can be applied data without relying any modelling theory gravity. It involves combination redshift-space distortions relativistic effects...
We present a novel approach for convenient tuning of the local refractive index around nanostructures. apply this technique to study influence on radiative decay time CdSe/ZnS quantum dots with three distinct emission wavelengths. The dependence luminescence environment is well described by an effective medium approach. A critical distance about 80 nm found determination refraction. An estimation emitting-state efficiency can be extracted.
When a luminous source is extended, its distortions by weak gravitational lensing are richer than mere combination of magnification and shear. In recent work, we proposed an elegant formalism based on complex analysis to describe calculate such distortions. The present article further elaborates this finite-beam approach, applies it realistic cosmological model. particular, the cosmic correlations image beyond shear predicted for first time. These constitute new weak-lensing observables,...