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Frédéric Courbin

Cette personne a quitté l’EPFL

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Publications associées (220)

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A fast empirical method for galaxy shape measurements in weak lensing surveys

Frédéric Courbin, Georges Meylan, Malte Tewes, Nicolas Jacques Joseph Marie Cantale

We describe a simple and fast method to correct ellipticity measurements of galaxies from the distortion by the instrumental and atmospheric point spread function (PSF), in view of weak lensing shear measurements. The method performs a classification of ga ...

Edp Sciences S A2012

Euclid IV. The NISP Calibration Unit

Frédéric Courbin, Georges Meylan

The near-infrared calibration unit (NI-CU) on board Euclid’s Near-Infrared Spectrometer and Photometer (NISP) is the first astronomical calibration lamp based on light-emitting diodes (LEDs) to be operated in space. Euclid is a mission in ESA’s Cosmic Visi ...

2025

Two Accurate Time-Delay Distances From Strong Lensing: Implications For Cosmology

Frédéric Courbin, Georges Meylan, Malte Tewes

Strong gravitational lenses with measured time delays between the multiple images and models of the lens mass distribution allow a one-step determination of the time-delay distance, and thus a measure of cosmological parameters. We present a blind analysis ...

American Astronomical Society2013

Dissecting cold gas in a high-redshift galaxy using a lensed background quasar

Frédéric Courbin

We present a study of cold gas absorption from a damped Lyman-alpha absorber (DLA) at redshift z(abs) = 1.946 toward two lensed images of the quasar J144254.78+405535.5 at redshift z(QSO) = 2.590. The physical separation of the two lines of sight at the ab ...

EDP SCIENCES S A2018

Euclid preparation XXXVI. Modelling the weak lensing angular power spectrum

Maurizio Martinelli, Frédéric Courbin, Georges Meylan, Gianluca Castignani, Austin Chandler Peel

This work considers which higher order modeling e ffects on the cosmic shear angular power spectra must be taken into account for Euclid. We identified the relevant terms and quantified their individual and cumulative impact on the cosmological parameter i ...

Edp Sciences S A2024

Discovery of the Lensed Quasar System DES J0408-5354

Frédéric Courbin, Georges Meylan, Eduardo Sanchez, Hung-Hsu Chan

We report the discovery and spectroscopic confirmation of the quad-like lensed quasar system DES J0408-5354 found in the Dark Energy Survey (DES) Year 1 (Y1) data. This system was discovered during a search for DES Y1 strong lensing systems using a method ...

Iop Publishing Ltd2017

A test for skewed distributions of dark matter, and a possible detection in galaxy cluster Abell 3827

Frédéric Courbin, David Richard Harvey, Rémy Elie Joseph

Simulations of self-interacting dark matter predict that dark matter should lag behind galaxies during a collision. If the interaction is mediated by a high-mass force carrier, the distribution of dark matter can also develop asymmetric dark matter tails. ...

Oxford Univ Press2017

Strong lensing in UNIONS: Toward a pipeline from discovery to modeling

Frédéric Courbin, Hung-Hsu Chan, Cameron Alexander Campbell Lemon, Georgios Vernardos, Benjamin Yvan Alexandre Clement, Karina Alexandra Rojas Olate, Elodie Marie Charlène Savary

We present a search for galaxy-scale strong gravitational lenses in the initial 2500 square degrees of the Canada-France Imaging Survey (CFIS). We designed a convolutional neural network (CNN) committee that we applied to a selection of 2 344 002 r-band im ...

EDP SCIENCES S A2022

Firedec: a two-channel finite-resolution image deconvolution algorithm

Frédéric Courbin, Georges Meylan, Pascale Jablonka, Malte Tewes, Nicolas Jacques Joseph Marie Cantale

We present a two-channel deconvolution method that decomposes images into a parametric point-source channel and a pixelized extended-source channel. Based on the central idea of the deconvolution algorithm proposed by Magain et al. (1998, ApJ, 494, 472), t ...

Edp Sciences S A2016

Euclid preparation: LXV. Determining the weak lensing mass accuracy and precision for galaxy clusters

Frédéric Courbin, Georges Meylan

The ability to measure unbiased weak-lensing (WL) masses is a key ingredient to exploit galaxy clusters as a competitive cosmological probe with the ESA Euclid survey or future missions. We investigate the level of accuracy and precision of cluster masses ...

2025

Quasi-stellar objects acting as potential strong gravitational lenses in the SDSS-III BOSS survey

Jean-Paul Richard Kneib, Frédéric Courbin, Timothée Guy Olivier Delubac

We present a sample of 12 quasi-stellar objects (QSOs) that potentially act as strong gravitational lenses on background emission line galaxies (ELG) or Lyman-alpha emitters (LAEs) selected through a systematic search of the 297 301 QSOs in the Sloan Digit ...

EDP SCIENCES S A2019

Euclid preparation XXII. Selection of quiescent galaxies from mock photometry using machine learning

Maurizio Martinelli, Frédéric Courbin, Georges Meylan, Gianluca Castignani, Austin Chandler Peel

The Euclid Space Telescope will provide deep imaging at optical and near-infrared wavelengths, along with slitless near-infrared spectroscopy, across similar to 15 000deg(2) of the sky. Euclid is expected to detect similar to 12 billion astronomical source ...

EDP SCIENCES S A2023

A weak lensing comparability study of galaxy mergers that host AGNs

Frédéric Courbin, David Richard Harvey

We compared the total mass density profiles of three different types of galaxies using weak gravitational lensing: (i) 29 galaxies that host quasars at (z) over bar similar to 0.32 that are in a post-starburst quasar (PSQ) phase with high star formation in ...

Wiley-Blackwell2015

ZEN2: a narrow J-band search for z similar to 9 Ly alpha emitting galaxies directed towards three lensing clusters

Jean-Paul Richard Kneib, Frédéric Courbin

We present the results of a continuing survey to detect Ly alpha emitting galaxies at redshifts z similar to 9: the z equals nine' (ZEN) survey. We have obtained deep VLT Infrared Spectrometer and Array Camera observations in the narrow J-band filter NB119 ...

Blackwell Publishing Ltd, Oxford2008

Euclid preparation XIX. Impact of magnification on photometric galaxy clustering

Frédéric Courbin, Georges Meylan

Aims. We investigate the importance of lensing magnification for estimates of galaxy clustering and its cross-correlation with shear for the photometric sample of Euclid. Using updated specifications, we study the impact of lensing magnification on the con ...

EDP SCIENCES S A2022

H0LiCOW. VI. Testing the fidelity of lensed quasar host galaxy reconstruction

Frédéric Courbin

The empirical correlation between the mass of a supermassive black hole (M-BH) and its host galaxy properties is widely considered to be an evidence of their co-evolution. A powerful way to test the co-evolution scenario and learn about the feedback proces ...

Oxford Univ Press2017

euclid Preparation: Lxiii. Simulations and Non-linearities Beyond Lambda Cold Dark Matter. 2. Results From Non-standard Simulations

Frédéric Courbin, Georges Meylan

The Euclid mission will measure cosmological parameters with unprecedented precision. To distinguish between cosmological models, it is essential to generate realistic mock observables from cosmological simulations that were run in both the standard Lambda ...

EDP SCIENCES S A2025

A 7 deg(2) survey for galaxy-scale gravitational lenses with the HST imaging archive(star)

Frédéric Courbin, Georges Meylan

We present the results of a visual search for galaxy-scale gravitational lenses in similar to 7 deg(2) of Hubble Space Telescope (HST) images. The data set comprises the whole imaging data ever taken with the Advanced Camera for Surveys (ACS) in the filter ...

Wiley-Blackwell2014

Euclid: Testing the Copernican principle with next-generation surveys

Frédéric Courbin, Georges Meylan

Context. The Copernican principle, the notion that we are not at a special location in the Universe, is one of the cornerstones of modern cosmology. Its violation would invalidate the Friedmann-Lemaitre-Robertson-Walker metric, causing a major change in ou ...

EDP SCIENCES S A2023

Euclid preparation XXXVII. Galaxy colour selections with Euclid and ground photometry for cluster weak-lensing analyses

Maurizio Martinelli, Frédéric Courbin, Georges Meylan, Gianluca Castignani, Matthias Wiesmann

Aims. We derived galaxy colour selections from Euclid and ground-based photometry, aiming to accurately define background galaxy samples in cluster weak-lensing analyses. These selections have been implemented in the Euclid data analysis pipelines for gala ...

Edp Sciences S A2024