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Georges Meylan

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Related publications (182)

Euclid preparation XVII. Cosmic Dawn Survey: Spitzer Space Telescope observations of the Euclid deep fields and calibration fields

We present a new infrared survey covering the three Euclid deep fields and four other Euclid calibration fields using Spitzer Space Telescope's Infrared Array Camera (IRAC). We combined these new observations with all relevant IRAC archival data of these f ...

EDP SCIENCES S A2022

Euclid preparation XVI. Exploring the ultra-low surface brightness Universe with Euclid/VIS

Georges Meylan, Gianluca Castignani

Context. While Euclid is an ESA mission specifically designed to investigate the nature of dark energy and dark matter, the planned unprecedented combination of survey area (similar to 15000 deg(2)), spatial resolution, low sky-background, and depth also m ...

EDP SCIENCES S A2022

European Astronomical Society prizes 2021

Georges Meylan

The European Astronomical Society awarded its most prestigious prizes during its annual meeting held from 28 June to 2 July 2021. In a way similar to last year, the meeting was entirely virtual. ...

2021

Euclid: Constraining dark energy coupled to electromagnetism using astrophysical and laboratory data

Georges Meylan

In physically realistic, scalar-field-based dynamical dark energy models (including, e.g., quintessence), one naturally expects the scalar field to couple to the rest of the model's degrees of freedom. In particular, a coupling to the electromagnetic secto ...

EDP SCIENCES S A2021

Euclid preparation: IX. EuclidEmulator2-power spectrum emulation with massive neutrinos and self-consistent dark energy perturbations

Georges Meylan, Fabio Finelli, Richard Massey, Gianluca Castignani, Yi Wang

We present a new, updated version of the EuclidEmulator (called EuclidEmulator2), a fast and accurate predictor for the nonlinear correction of the matter power spectrum. 2 per cent level accurate emulation is now supported in the eight-dimensional paramet ...

OXFORD UNIV PRESS2021

Euclid Preparation. XIV. The Complete Calibration of the Color-Redshift Relation (C3R2) Survey: Data Release 3

Georges Meylan, Gianluca Castignani

The Complete Calibration of the Color-Redshift Relation (C3R2) survey is obtaining spectroscopic redshifts in order to map the relation between galaxy color and redshift to a depth of i similar to 24.5 (AB). The primary goal is to enable sufficiently accur ...

IOP PUBLISHING LTD2021

Euclid preparation XII. Optimizing the photometric sample of the Euclid survey for galaxy clustering and galaxy-galaxy lensing analyses

Georges Meylan, Gianluca Castignani

Photometric redshifts (photo-zs) are one of the main ingredients in the analysis of cosmological probes. Their accuracy particularly affects the results of the analyses of galaxy clustering with photometrically selected galaxies (GC(ph)) and weak lensing. ...

EDP SCIENCES S A2021

EUCLID: FORECASTS FOR K-CUT 3 × 2 POINT STATISTICS

Georges Meylan

Modelling uncertainties at small scales, i.e. high k in the power spectrum P (k), due to baryonic feedback, nonlinear structure growth and the fact that galaxies are biased tracers poses a significant obstacle to fully leverage the constraining power of th ...

2021

Euclid : Effects of sample covariance on the number counts of galaxy clusters

Georges Meylan, Richard Massey, Yi Wang

Aims. We investigate the contribution of shot-noise and sample variance to uncertainties in the cosmological parameter constraints inferred from cluster number counts, in the context of the Euclid survey. ...

EDP SCIENCES S A2021

Euclid: Estimation of the Impact of Correlated Readout Noise for Flux Measurements with the Euclid NISP Instrument

Georges Meylan

The Euclid satellite, to be launched by ESA in 2022, will be a major instrument for cosmology for the next decades. Euclid is composed of two instruments: the Visible instrument and the Near Infrared Spectrometer and Photometer (NISP). In this work, we est ...

IOP PUBLISHING LTD2021

H0LiCOW-XIII. A 2.4 per cent measurement of H-0 from lensed quasars: 5.3 sigma tension between early- and late-Universe probes

Georges Meylan, Frédéric Courbin, Vivien François Bonvin, Martin Raoul Robert Millon, Olga Tihhonova, Hung-Hsu Chan, Adriano Agnello

We present a measurement of the Hubble constant (H-0) and other cosmological parameters from a joint analysis of six gravitationally lensed quasars with measured time delays. All lenses except the first are analysed blindly with respect to the cosmological ...

OXFORD UNIV PRESS2020

Euclid preparation: X. The Euclid photometric-redshift challenge

Georges Meylan, Gianluca Castignani

Forthcoming large photometric surveys for cosmology require precise and accurate photometric redshift (photo-z) measurements for the success of their main science objectives. However, to date, no method has been able to produce photo-zs at the required acc ...

EDP SCIENCES S A2020

Euclid preparation VIII. The Complete Calibration of the Colour-Redshift Relation survey: VLT/KMOS observations and data release

Murat Kunt, Santiago Serrano Guisan, Georges Meylan, Richard Massey, Gianluca Castignani, Yi Wang

The Complete Calibration of the Colour-Redshift Relation survey (C3R2) is a spectroscopic e ffort involving ESO and Keck facilities designed specifically to empirically calibrate the galaxy colour-redshift relation - P(z jC) to the Euclid depth (iAB = 24 : ...

EDP SCIENCES S A2020

COSMOGRAIL: XIX. Time delays in 18 strongly lensed quasars from 15 years of optical monitoring star

Malte Tewes, Georges Meylan, Frédéric Courbin, Vivien François Bonvin, Martin Raoul Robert Millon, Aymeric Alexandre Galan, Eric Gérard Guy Paic, Rémy Elie Joseph, Olga Tihhonova, Hung-Hsu Chan, Cameron Alexander Campbell Lemon

We present the results of 15 years of monitoring lensed quasars, which was conducted by the COSMOGRAIL programme at the Leonhard Euler 1.2 m Swiss Telescope. The decade-long light curves of 23 lensed systems are presented for the first time. We complement ...

EDP SCIENCES S A2020

Euclid: Reconstruction of weak-lensing mass maps for non-Gaussianity studies

Georges Meylan, Richard Massey, Yi Wang

Weak lensing, which is the deflection of light by matter along the line of sight, has proven to be an efficient method for constraining models of structure formation and reveal the nature of dark energy. So far, most weak-lensing studies have focused on th ...

EDP SCIENCES S A2020

H0LiCOW-XI. A weak lensing measurement of the external convergence in the field of the lensed quasar B1608+656 using HST and Subaru deep imaging

Georges Meylan, Frédéric Courbin, Vivien François Bonvin, David Richard Harvey, Olga Tihhonova, Austin Chandler Peel

We investigate the environment and line of sight (LoS) of the H0LiCOW (H-0 Lenses in COSMOGRAIL's Wellspring) lens B1608+656 using Subaru Suprime-Cam and the Hubble Space Telescope (HST) to perform a weak lensing analysis. We compare three different method ...

OXFORD UNIV PRESS2020

STRIDES: a 3.9 per cent measurement of the Hubble constant from the strong lens system DES J0408-5354

Georges Meylan, Frédéric Courbin, Vivien François Bonvin, Martin Raoul Robert Millon, Aymeric Alexandre Galan, Cameron Alexander Campbell Lemon

We present a blind time-delay cosmographic analysis for the lens system DES J0408-5354. This system is extraordinary for the presence of two sets of multiple images at different redshifts, which provide the opportunity to obtain more information at the cos ...

OXFORD UNIV PRESS2020

Euclid: Identification of asteroid streaks in simulated images using StreakDet software

Georges Meylan

Context. The ESA Euclid space telescope could observe up to 150 000 asteroids as a side product of its primary cosmological mission. Asteroids appear as trailed sources, that is streaks, in the images. Owing to the survey area of 15 000 square degrees and ...

EDP SCIENCES S A2020

Euclid: the selection of quiescent and star-forming galaxies using observed colours

Georges Meylan, Richard Massey, Yi Wang

The Euclid mission will observe well over a billion galaxies out to z similar to 6 and beyond. This will offer an unrivalled opportunity to investigate several key questions for understanding galaxy formation and evolution. The first step for many of these ...

OXFORD UNIV PRESS2020

Euclid preparation: VII. Forecast validation for Euclid cosmological probes

Murat Kunt, Slobodan Ilic, Georges Meylan, Richard Massey, Maurizio Martinelli, Jean-Luc Starck, Yi Wang

Aims. The Euclid space telescope will measure the shapes and redshifts of galaxies to reconstruct the expansion history of the Universe and the growth of cosmic structures. The estimation of the expected performance of the experiment, in terms of predicted ...

EDP SCIENCES SA2020

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