A5050309898- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Dark Matter and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Scientific Research and Discoveries
- Gaussian Processes and Bayesian Inference
- Geophysics and Gravity Measurements
- Gamma-ray bursts and supernovae
- Statistical and numerical algorithms
- Superconducting and THz Device Technology
- Computational Physics and Python Applications
- Astrophysical Phenomena and Observations
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Solar and Space Plasma Dynamics
- Relativity and Gravitational Theory
- Radioactive Decay and Measurement Techniques
- Advanced Differential Geometry Research
- Calibration and Measurement Techniques
- Adaptive optics and wavefront sensing
- Black Holes and Theoretical Physics
Sorbonne Université
2016-2025
Centre National de la Recherche Scientifique
2016-2025
Institut d'Astrophysique de Paris
2016-2025
Johns Hopkins University
2025
Flatiron Institute
2018-2024
Flatiron Health (United States)
2018-2024
Computational Physics (United States)
2024
Princeton University
2000-2022
University of California, Berkeley
2018-2020
University of Illinois Urbana-Champaign
2010-2019
HEALPix -- the Hierarchical Equal Area iso-Latitude Pixelization is a versatile data structure with an associated library of computational algorithms and visualization software that supports fast scientific applications executable directly on very large volumes astronomical area surveys in form discretized spherical maps. Originally developed to address processing analysis needs present generation cosmic microwave background (CMB) experiments (e.g. BOOMERanG, WMAP), can be expanded meet many...
The only direct measurements of interstellar magnetic field strengths depend on the Zeeman effect, which samples line-of-sight component Bz vector. In this paper, we use a Bayesian approach to analyze observed probability density function (PDF) from surveys H i, OH, and CN spectral lines in order infer density-dependent stochastic model total strength B diffuse molecular clouds. We find that at n < 300 cm−3 (in medium sampled by i lines), does not scale with density. This suggests clouds are...
We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes physics inflation. focus on prospects for using CMB to differentiate various inflationary mechanisms. In particular, a detection primordial B‐mode would demonstrate that inflation occurred at very high energy scale, and inflaton traversed super‐Planckian distance in field space. explain how such or constraint illuminate aspects Planck scale. Moreover, can constrain scale‐dependence...
We present a fully probabilistic, physical model of the non-linearly evolved density field, as probed by realistic galaxy surveys. Our is valid in linear and mildly non-linear regimes uses second-order Lagrangian perturbation theory to connect initial conditions with final field. parameter space consists 3D field our method allows Bayesian exploration sets that are consistent distribution sampling A natural by-product this technique an optimal reconstruction velocity fields, including full...
Abstract Likelihood-free inference provides a framework for performing rigorous Bayesian using only forward simulations, properly accounting all physical and observational effects that can be successfully included in the simulations. The key challenge likelihood-free applications cosmology, where simulation is typically expensive, developing methods achieve high-fidelity posterior with as few simulations possible. Density-estimation (DELFI) turn into density estimation task on set of...
Gravitational waves can provide an accurate measurement of the luminosity distance to source but cannot redshift unless degeneracy between mass and be broken. This makes it essential infer independently measure expansion history Universe. We show that by exploiting clustering scale gravitational wave sources with galaxies a known redshift, we from unknown sources. By using are detectable network detectors Advanced LIGO design sensitivity, will able obtain precise measurements local Hubble...
Abstract Cosmological inference relies on compressed forms of the raw data for analysis, with traditional methods exploiting physics knowledge to define summary statistics, such as power spectra, that are known capture much information. An alternative approach is ask a neural network find set informative statistics from data, which can then be analysed either by likelihood- or simulation-based inference. This has advantage non-Gaussian fields, they may more information than two-point...
We present a comparison of halo properties in cosmological simulations collisionless cold dark matter (CDM) and self-interacting (SIDM) for range cross sections. find, agreement with various authors, that CDM yields cuspy halos are too centrally concentrated as compared to observations. Conversely, SIDM using Monte Carlo N-body technique produce significantly reduced central densities flatter cores. introduce concentration parameter based on enclosed mass we expect will be straightforward...
We present evidence for primordial non-Gaussianity of the local type (${f}_{\mathrm{NL}}$) in temperature anisotropy cosmic microwave background. Analyzing bispectrum Wilkinson Microwave Anisotropy Probe 3-year data up to ${\ensuremath{\ell}}_{\mathrm{max}}=750$ we find $27<{f}_{\mathrm{NL}}<147$ (95% C.L.). This amounts a rejection ${f}_{\mathrm{NL}}=0$ at $2.8\ensuremath{\sigma}$, disfavoring canonical single-field slow-roll inflation. The signal is robust variations ${l}_{\mathrm{max}}$,...
We derive a fast way for measuring primordial non-Gaussianity in nearly full-sky map of the cosmic microwave background. find cubic combination sky maps combining bispectrum configurations to capture quadratic term fluctuations. Our method takes only N3/2 operations rather than N5/2, as taken by analysis (1000 times faster l = 512), retaining same sensitivity. A key component is underlying fluctuations, which can be more sensitive temperature map. also and accurate statistic non-Gaussian...
We describe an efficient and exact method that enables global Bayesian analysis of cosmic microwave background (CMB) data. The reveals the joint posterior density (or likelihood for flat priors) power spectrum ${C}_{\ensuremath{\ell}}$ CMB signal. Foregrounds instrumental parameters can be simultaneously inferred from allows specification a wide range foreground priors. explicitly show how to propagate non-Gaussian dependency structure through parameters. If desired, coupled theoretical...
We revisit a recently introduced power spectrum estimation technique based on Gibbs sampling, with the goal of applying it to high-resolution WMAP data. In order facilitate this analysis, number sophistications have be introduced, each which is discussed in detail. implemented two independent versions algorithm cross-check computer codes and verify that particular solution any given problem does not affect scientific results. then apply these programs simulated data known properties at...
We present a simple empirical function for the average density profile of cosmic voids, identified via watershed technique in $\Lambda$CDM N-body simulations. This is universal across void size and redshift, accurately describing large radial range scales around centers with only two free parameters. In analogy to halo profiles, these parameters describe scale radius central voids. While we initially start more general four-parameter model, find its be redundant, as they follow linear trends...
COrE (Cosmic Origins Explorer) is a fourth-generation full-sky, microwave-band satellite recently proposed to ESA within Cosmic Vision 2015-2025. will provide maps of the microwave sky in polarization and temperature 15 frequency bands, ranging from 45 GHz 795 GHz, with an angular resolution 23 arcmin (45 GHz) 1.3 (795 sensitivities roughly 10 30 times better than PLANCK (depending on channel). The mission lead breakthrough science wide range areas, primordial cosmology galactic...
The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content predominantly distributed along their boundaries. remaining material inside them, either dark or luminous matter, attracted to these boundaries causes voids expand faster grow emptier over time. Using the distribution galaxies centered on identified in Sloan Digital Sky Survey adopting minimal assumptions statistical motion galaxies, we constrain average Ω_{m}=0.281±0.031...
We show that the number of observed voids in galaxy redshift surveys is a sensitive function equation state dark energy. Using Fisher matrix formalism we find error ellipses $w_0-w_a$ plane when energy assumed to be form $w_{CPL}(z)=w_0 +w_a z/(1+z)$. forecast with ESA Euclid satellite and NASA WFIRST mission, taking into account updated details reach accurate estimates their power. The theoretical model for based on matches between abundances simulations analytical prediction. To take...
We present a purely geometrical method for probing the expansion history of Universe from observation shape stacked voids in spectroscopic redshift surveys. Our is an Alcock-Paczynski (AP) test based on average sphericity posited local isotropy Universe. It works by comparing temporal extent cosmic along line sight with their angular, spatial extent. describe algorithm that we use to detect and stack shells light cone it mock cones produced N-body simulations. establish robust statistical...
Many statistical models in cosmology can be simulated forwards but have intractable likelihood functions. Likelihood-free inference methods allow us to perform Bayesian from these using only forward simulations, free any assumptions or approximations. generically involves simulating mock data and comparing the observed data; this comparison space suffers curse of dimensionality requires compression a small number summary statistics tractable. In paper, we use massive asymptotically optimal...
We propose a new definition of cosmic voids based on methods Lagrangian orbit reconstruction as well an algorithm to find them in actual data called DIVA. Our technique is intended yield results which can be modeled sufficiently accurately create probe precision cosmology. then develop analytical model the ellipticity found by our method Zel'dovich approximation. measure N-body simulation that this precise at 0.1% level for mean size greater than ~4 Mpc/h. estimate scale, we are able predict...
[Abridged] We present a new approach to investigate the content and spatial distribution of dust in structurally unresolved star-forming galaxies from observed dependence integrated spectral properties on galaxy inclination. develop an innovative combination generic models radiative transfer (RT) dusty media with prescription for evolution galaxies, via association different geometric components stars age ranges. show that wide range RT all predict quasi-universal relation between slope...