A5083132997- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Black Holes and Theoretical Physics
- Scientific Research and Discoveries
- Dark Matter and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Solar and Space Plasma Dynamics
- Quantum, superfluid, helium dynamics
- Methane Hydrates and Related Phenomena
- Stochastic processes and financial applications
- Stochastic processes and statistical mechanics
- Data Visualization and Analytics
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- Advanced Fluorescence Microscopy Techniques
- Complex Network Analysis Techniques
- Particle physics theoretical and experimental studies
- Plant and animal studies
- Blind Source Separation Techniques
- Geological and Geophysical Studies
- Ecology and Vegetation Dynamics Studies
- Spectroscopy and Laser Applications
Universidad de Salamanca
2023
University of Rwanda
2018-2021
Max Planck Institute for Astrophysics
2016-2021
Deutsches Elektronen-Synchrotron DESY
2021
Institute for Fundamental Physics of the Universe
2021
Sorbonne Université
2018
Centre National de la Recherche Scientifique
2005-2018
Institut d'Astrophysique de Paris
2005-2018
Institut de Physique Théorique
2017-2018
CEA Paris-Saclay
2017-2018
The role of the cosmic web in shaping galaxy properties is investigated GAMA spectroscopic survey redshift range $0.03 \leq z 0.25$. stellar mass, $u - r$ dust corrected colour and specific star formation rate (sSFR) galaxies are analysed as a function their distances to 3D features, such nodes, filaments walls, reconstructed by DisPerSE. Significant mass type/colour gradients found for whole population, with more massive and/or passive being located closer filament wall than less...
We study the consequences of imposing an approximate Galilean symmetry on Effective Theory Inflation, theory small perturbations around inflationary background. This approach allows us to effect operators with two derivatives each field, which can be leading interactions due non-renormalization properties Lagrangian. In this case cubic non-Gaussianities are given by three independent operators, containing up six derivatives, a shape close equilateral and one peaking flattened isosceles...
We provide a simple formula that accurately approximates the first crossing distribution of barriers having wide variety shapes, by random walks with range correlations between steps. Special cases it are useful for estimating halo abundances, evolution, and bias, as well nonlinear counts in cells distribution. discuss how can be extended to allow dependence barrier on quantities other than overdensity, construct an excursion set model peaks, show why assembly scale dependent bias generic...
We prove that, in a generic single-field model, the consistency relation for 3-point function squeezed limit receives corrections that vanish quadratically ratio of momenta, i.e. as (k_L/k_S)^2. This implies detection bispectrum signal going 1/k_L^2 limit, is suppressed only by one power k_L compared with local shape, would rule out all models. The absence this kind terms holds also multifield models, but if fields have mass much smaller than H. any scale dependence bias, scales larger size...
The mass, accretion rate, and formation time of dark matter haloes near protofilaments (identified as saddle points the potential) are analytically predicted using a conditional version excursion set approach in its so-called upcrossing approximation. model predicts that at fixed mass rate vary with orientation distance from saddle, demonstrating assembly bias is indeed influenced by tides imposed cosmic web. Starved, early-forming smaller lie preferentially along main axis filaments, while...
We consider the application of peaks theory to calculation number density relevant for primordial black hole (PBH) formation. For PBHs, final mass is related amplitude and scale perturbation from which it forms, where defined as at compaction function peaks. therefore extend calculate not only abundance a given amplitude, but scale. A simple fitting formula in high-peak limit PBH also adapt use Gaussian smoothing function, ensuring convergence regardless choice power spectrum.
We present precise measurements of the assembly bias dark matter halos, i.e. dependence halo on other properties than mass, using curved "separate universe" N-body simulations which effectively incorporate an infinite-wavelength overdensity into background density. This method measures LIMD (local-in-matter-density) parameters bn in large-scale limit. focus first two Eulerian biases bE1 and bE2 four properties: concentration, spin, mass accretion rate, ellipticity. quantitatively compare our...
We investigate the impact of number filaments connected to nodes cosmic web on physical properties their galaxies using Sloan Digital Sky Survey. compare these measurements cosmological hydrodynamical simulations Horizon-(no)AGN and Simba. find that more massive are connected, in qualitative agreement with theoretical predictions dark matter only simulation. The star formation activity morphology observed both display some dependence connectivity at fixed stellar mass: less forming rotation...
If one accounts for correlations between scales, then non-local, k-dependent halo bias is part and parcel of the excursion set approach, hence model predictions galaxy bias. We present an analysis that distinguishes a number different effects, each which contributes to scale-dependent in real space. show how isolate these effects remove scale dependence, order by order, cross-correlating field with suitably transformed versions mass field. These transformations may be thought as simple...
The strikingly anisotropic large-scale distribution of matter made an extended network voids delimited by sheets, themselves segmented filaments, within which flows towards compact nodes where they intersect, imprints its geometry on the dynamics cosmic flows, ultimately shaping galaxies and redshift evolution their properties. (filament-type) saddle points this web provide a local frame in to quantify induced physical morphological large scales. properties virtual Horizon-AGN simulation are...
We prove an exact relation between the tensor and scalar primordial power spectra generated during inflation. Such a mapping considerably simplifies derivation of any as they can be obtained from study modes only, which are much easier to solve. As illustration, starting second order slow-roll spectrum, we derive in few lines next-to-next-to-leading spectrum comoving curvature perturbation generalized single field inflation with varying speed sound.
We generalize the treatment of inflationary perturbations to deal with non-Markovian coloured noise emerging from any realistic approach stochastic inflation. provide a calculation power spectrum gauge-invariant comoving curvature perturbation first order in slow-roll parameters. Properly accounting for constraint that our local patch Universe is homogeneous on scales just above present Hubble radius, we find blue tilt largest observable scales, agreement WMAP data which show an unexpected...
Primordial non-Gaussianity (NG) affects the large scale structure (LSS) of universe by leaving an imprint on distribution matter at late times. Much attention has been focused using collapsed objects (i.e. dark halos and galaxies galaxy clusters that reside in them) to probe primordial NG. An equally interesting complementary however is abundance extended underdense regions or voids LSS. The calculation excursion set formalism presence NG subject same technical issues as one for halos, which...
The abundance of collapsed objects in the universe, or halo mass function, is an important theoretical tool studying effects primordially generated non-Gaussianities on large scale structure. non-Gaussian function has been calculated by several authors different ways, typically exploiting smallness certain parameters which naturally appear calculation, to set up a perturbative expansion. We improve upon existing results for combining path integral methods and saddle point techniques (which...
Using the techniques of out-of-equilibrium field theory, we study influence on properties cosmological perturbations generated during inflation observable scales coming from fluctuations corresponding today to much bigger than present Hubble radius. We write effective action for coarse-grained inflaton integrating out sub-horizon modes, which manifest themselves as a colored noise and lead memory effects. simple model scalar with cubic self-interactions evolving in fixed de Sitter...
There is a simple analytic approximation for the first crossing distribution associated with random walks having correlated steps, which very accurate in limit of few steps. The wide range barrier shapes interest excursion set studies cosmological structure formation. For example, it provides useful fitting formula high-mass end dark halo mass function. based on requirement that, addition to right height, walk must cross going upwards. Therefore, only requires knowledge bivariate height and...
The dark matter halos that host galaxies and clusters form out of initial high-density patches, providing a biased tracer the linear density field. In simplest local bias approximation, halo field is treated as perturbative series in average overdensity Lagrangian patch. more realistic models, however, additional quantities will affect clustering this expansion becomes function several stochastic variables. paper, we present general multivariate scheme can parametrize any tracer, given only...
A perturbative method for solving the Langevin equation of inflationary cosmology in presence backreaction is presented. In Gaussian approximation, permits an explicit calculation probability distribution inflaton field arbitrary potential, with or without volume effects taken into account. The then applied to various concrete models, namely, large field, small hybrid, and running mass inflation. New results on stochastic behavior those models are obtained. particular, it confirmed that can...
The merging rate of cosmic structures is computed, relying on the Ansatz that they can be predicted in initial linear density field from coalescence critical points with increasing smoothing scale, used here as a proxy for time. Beyond mergers peaks saddle (a halo mergers), we consider and nucleation all sets points, including wall-saddle to filament-saddle minima filament void respectively), impact geometry galactic infall, particular disconnection. Analytical predictions one-point...
A method to estimate the reliability of a perturbative expansion stochastic inflationary Langevin equation is presented and discussed. The applied various scenarios, as large field, small running mass models. It demonstrated that approach more reliable than could be na\"{\i}vely suspected and, in general, only breaks down at very end inflation.
We study the effects of primordial non-Gaussianity on large-scale structure in excursion set approach, accounting for correlations between steps random walks smoothed initial density field. These are induced by realistic smoothing filters (as opposed to a filter that is sharp k-space), but have been ignored many analyses date. present analytical arguments – building existing results Gaussian conditions which suggest effect at large scales remarkably simple, and fact identical what happens...
The excursion set approach uses the statistics of density field smoothed on a wide range scales, to gain insight into number interesting processes in non-linear structure formation, such as cluster assembly, merging and clustering. treats curve defined by height overdensity fluctuation when changing smoothing scale random walk. steps walks are often assumed be uncorrelated, so that walk heights Markov process, even though this assumption is known inaccurate for physically relevant filters....
Insight into a number of interesting questions in cosmology can be obtained from the first crossing distributions physically motivated barriers by random walks with correlated steps. We write distribution as formal series, ordered times walk upcrosses barrier. Since fraction many upcrossings is negligible if has not taken steps, leading order term this series most relevant for understanding massive objects interest cosmology. This only requires knowledge bivariate height and slope, provides...
The behavior of the quintessence field is studied during inflation. In order to have a satisfactory model dark energy, value today should be as insensible initial conditions possible. Usually, only dependence on specified at end inflation or, equivalently, beginning radiation dominated era, considered. Provided initially within large but, crucially, finite interval, its present becomes independent it started from. question whether naturally drives above-mentioned interval addressed. Since...