P.-F. Léget
A5067115416- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Adaptive optics and wavefront sensing
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- CCD and CMOS Imaging Sensors
- Distributed and Parallel Computing Systems
- Astro and Planetary Science
- Statistical and numerical algorithms
- Anomaly Detection Techniques and Applications
- Particle Detector Development and Performance
- High-Energy Particle Collisions Research
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Remote Sensing in Agriculture
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
Kavli Institute for Particle Astrophysics and Cosmology
2018-2025
Menlo School
2024-2025
Stanford University
2018-2024
Sorbonne Université
2019-2023
Institut National de Physique Nucléaire et de Physique des Particules
2018-2023
Centre National de la Recherche Scientifique
2014-2023
Université Paris Cité
2019-2023
Laboratoire de Physique Nucléaire et de Hautes Énergies
2019-2023
Université Clermont Auvergne
2014-2022
Clermont Université
2014-2022
We present the first cosmology results from large-scale structure in Dark Energy Survey (DES) spanning 5000 deg$^2$. perform an analysis combining three two-point correlation functions (3$\times$2pt): (i) cosmic shear using 100 million source galaxies, (ii) galaxy clustering, and (iii) cross-correlation of with lens positions. The was designed to mitigate confirmation or observer bias; we describe specific changes made sample following unblinding results. model data within flat $\Lambda$CDM...
This work, together with its companion paper, Secco and Samuroff et al. (2021), presents the Dark Energy Survey Year 3 cosmic shear measurements cosmological constraints based on an analysis of over 100 million source galaxies. With data spanning 4143 deg$^2$ sky, divided into four redshift bins, we produce highest significance measurement to date, a signal-to-noise 40. We conduct blind in context $\Lambda$CDM model find 3% constraint clustering amplitude, $S_8\equiv \sigma_8 (\Omega_{\rm...
This work and its companion paper, Amon et al. (2021), present cosmic shear measurements cosmological constraints from over 100 million source galaxies in the Dark Energy Survey (DES) Year 3 data. We constrain lensing amplitude parameter $S_8\equiv\sigma_8\sqrt{\Omega_\textrm{m}/0.3}$ at 3% level $\Lambda$CDM: $S_8=0.759^{+0.025}_{-0.023}$ (68% CL). Our constraint is 2% when using angular scale cuts that are optimized for $\Lambda$CDM analysis: $S_8=0.772^{+0.018}_{-0.017}$ With alone, we...
Previously we used the Nearby Supernova Factory sample to show that Type Ia supernovae (SNe Ia) having locally star-forming environments are dimmer than SNe passive environments. Here use Constitution together with host galaxy data from GALEX independently confirm result. The effect is seen using both SALT2 and MLCS2k2 lightcurve fitting standardization methods, brightness differences of 0.094 ± 0.037 mag for 0.155 0.041 RV = 2.5. When combined our previous measurement 0.025 SALT2. If ratio...
As part of an on-going effort to identify, understand and correct for astrophysics biases in the standardization Type Ia supernovae (SNIa) cosmology, we have statistically classified a large sample nearby SNeIa into those located predominantly younger or older environments. This classification is based on specific star formation rate measured within projected distance 1kpc from each SN location (LsSFR). important refinement compared using local directly as it provides normalization relative...
We present a joint cosmic shear analysis of the Dark Energy Survey (DES Y3) and Kilo-Degree (KiDS-1000) in collaborative effort between two survey teams. find consistent cosmological parameter constraints DES Y3 KiDS-1000 which, when combined joint-survey analysis, constrain $S_8 = \sigma_8 \sqrt{\Omega_{\rm m}/0.3}$ with mean value $0.790^{+0.018}_{-0.014}$. The marginal is lower than maximum posteriori estimate, $S_8=0.801$, owing to skewness distribution projection effects...
The authors use Dark Energy Survey data on galaxy clustering and lensing from the first three years of observations combined with five prominent external datasets. They robustly constrain six potential extensions to currently prevalent cosmological paradigm \ensuremath{\Lambda}CDM (Cold Matter a constant). All would add significant new physics, such as deviations General Relativity or non-zero spatial curvature, but no evidence for physics is found.
We present cosmological constraints from the analysis of two-point correlation functions between galaxy positions and lensing measured in Dark Energy Survey (DES) Year 3 data measurements cosmic microwave background (CMB) South Pole Telescope (SPT) Planck. When jointly analyzing DES-only DES cross-correlations with SPT+Planck CMB lensing, we find Ωm=0.344±0.030 S8≡σ8(Ωm/0.3)0.5=0.773±0.016, assuming ΛCDM. additionally combining autospectrum, Ωm=0.306+0.018−0.021 S8=0.792±0.012. The high...
The Large Synoptic Survey Telescope (LSST) Dark Energy Science Collaboration (DESC) will use five cosmological probes: galaxy clusters, large scale structure, supernovae, strong lensing, and weak lensing. This Requirements Document (SRD) quantifies the expected dark energy constraining power of these probes individually together, with conservative assumptions about analysis methodology follow-up observational resources based on our current understanding evolution within field in coming...
ABSTRACT We present reconstructed convergence maps, mass from the Dark Energy Survey (DES) third year (Y3) weak gravitational lensing data set. The maps are weighted projections of density field (primarily dark matter) in foreground observed galaxies. use four reconstruction methods, each is a maximum posteriori estimate with different model for prior probability map: Kaiser–Squires, null B-mode prior, Gaussian and sparsity prior. All methods implemented on celestial sphere to accommodate...
We constrain the matter density $\Omega_{\mathrm{m}}$ and amplitude of fluctuations $\sigma_8$ within $\Lambda$CDM cosmological model with shear peak statistics angular convergence power spectra using mass maps constructed from first three years data Dark Energy Survey (DES Y3). use tomographic statistics, including cross-peaks: counts calculated on created by taking a harmonic space product two redshift bins. Our analysis follows forward-modelling scheme to create likelihood these N-body...
We present a cosmological analysis using the second and third moments of weak lensing mass (convergence) maps from first three years data (Y3) Dark Energy Survey. The survey spans an effective area 4139 square degrees uses images over 100 million galaxies to reconstruct convergence field. moment as function smoothing scale contains information similar standard shear 2-point statistics. moment, or skewness, additional non-Gaussian information. is analyzed in context...
We present and characterize the galaxy-galaxy lensing signal measured using first three years of data from Dark Energy Survey (DES Y3) covering 4132 deg$^2$. These measurements are used in DES Y3 3$\times$2pt cosmological analysis, which combines weak galaxy clustering information. use two lens samples: a magnitude-limited sample redMaGic sample, span redshift range $\sim 0.2-1$ with 10.7 M 2.6 galaxies respectively. For source catalog, we Metacalibration shape consisting $\simeq$100...
Cross-correlations of galaxy positions and shears with maps gravitational lensing the cosmic microwave background (CMB) are sensitive to distribution large-scale structure in Universe. Such cross-correlations also expected be immune some systematic effects that complicate correlation measurements internal surveys. We present modeling between measured first three years data from Dark Energy Survey CMB derived a combination 2500 deg2 SPT-SZ survey conducted South Pole Telescope full-sky Planck...
We study the effect of magnification in Dark Energy Survey Year 3 analysis galaxy clustering and galaxy-galaxy lensing, using two different lens samples: a sample Luminous red galaxies, redMaGiC, with redshift-dependent magnitude limit, MagLim. account for on both flux size selection accounting systematic effects Balrog image simulations. estimate impact lensing cosmology analysis, finding it to be significant MagLim sample. show cosmological constraints from auto-correlation signal...
We present optical photometry and spectra of the superluminous Type II/IIn supernova (SN) CSS121015:004244+132827 (z = 0.2868) spanning epochs from −30 d (rest frame) to more than 200 after maximum. CSS121015 is one luminous SNe ever found best observed. The photometric evolution characterized by a relatively fast rise maximum (∼40 in SN rest frame), linear post-maximum decline. light curve shows no sign break an exponential tail. A broad Hα first detected at ∼+40 frame). Narrow, barely...
We introduce a new software package for modeling the point-spread function (PSF) of astronomical images, called Piff (PSFs In Full FOV), which we apply to first three years (known as Y3) Dark Energy Survey (DES) data. describe relevant details about algorithms used by model PSF, including how PSF varies across field view (FOV). Diagnostic results show that systematic errors from are very small over range scales important DES Y3 weak lensing analysis. particular, significantly smaller than...
Using the first three years of data from Dark Energy Survey, we use ratios small-scale galaxy-galaxy lensing measurements around same lens sample to constrain source redshift uncertainties, intrinsic alignments and other nuisance parameters our model. Instead using a simple geometric approach for ratios, full modeling measurements, including corresponding integration over power spectrum contributions magnification. We perform extensive testing shear ratio (SR) by studying impact different...
Joint analyses of cross-correlations between measurements galaxy positions, lensing, and lensing the cosmic microwave background (CMB) offer powerful constraints on large-scale structure Universe. In a forthcoming analysis, we will present cosmological from analysis such measured using Year 3 data Dark Energy Survey (DES), CMB South Pole Telescope (SPT) Planck. Here two key ingredients this analysis: (1) an improved map in SPT-SZ survey footprint, (2) methodology that be used to extract...
We present a simulation-based cosmological analysis using combination of Gaussian and non-Gaussian statistics the weak lensing mass (convergence) maps from first three years (Y3) Dark Energy Survey (DES). implement: 1) second third moments; 2) wavelet phase harmonics; 3) scattering transform. Our is fully based on simulations, spans space seven $\nu w$CDM parameters, forward models most relevant sources systematics inherent in data: masks, noise variations, clustering sources, intrinsic...
We present photometric and spectroscopic observations of the interacting transient SN 2009ip taken during 2013 2014 observing seasons. characterize evolution as a steady smooth decline in all bands, with rate that is slower than expected for solely 56Co-powered supernova at late phases. No further outbursts or eruptions were seen over two year period from 2012 December until December. remains brighter its historic minimum pre-discovery images. Spectroscopically, continues to be dominated by...
Type Ia supernova cosmology depends on the ability to fit and standardize observations of magnitudes with an empirical model. We present here a series new models Supernova spectral time that capture greater amount diversity than possible are currently customary. These entitled SuperNova Empirical MOdels (\textsc{SNEMO}\footnote{https://snfactory.lbl.gov/snemo}). The constructed using spectrophotometric from $172$ individual supernovae Nearby Factory, comprising more $2000$ spectra. Using...
ABSTRACT We measure the impact of source galaxy clustering on higher order summary statistics weak gravitational lensing data. By comparing simulated data with galaxies that either trace or do not underlying density field, we show this effect can exceed measurement uncertainties for common certain analysis choices. evaluate different observables, finding third moments and wavelet phase harmonics are more affected than peak count statistics. Using Dark Energy Survey (DES) Year 3 (Y3) data,...
ABSTRACT Extracting precise cosmology from weak lensing surveys requires modelling the non-linear matter power spectrum, which is suppressed at small scales due to baryonic feedback processes. However, hydrodynamical galaxy formation simulations make widely varying predictions for amplitude and extent of this effect. We use measurements Dark Energy Survey Year 3 (WL) Atacama Cosmology Telescope DR5 kinematic Sunyaev–Zel’dovich (kSZ) jointly constrain cosmological astrophysical parameters...