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Frédéric Courbin

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Related publications (220)

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TOCOSMO VIII. A key test of systematics in the hierarchical method of time-delay cosmography

Frédéric Courbin

The largest source of systematic errors in the time-delay cosmography method likely arises from the lens model mass distribution, where an inaccurate choice of model could in principle bias the value of H-0. A Bayesian hierarchical framework has been propo ...

EDP SCIENCES S A2022

Multi-band morpho-Spectral Component Analysis Deblending Tool (MuSCADeT): Deblending colourful objects

Frédéric Courbin, Rémy Elie Joseph

We introduce a new algorithm for colour separation and deblending of multi-band astronomical images called MuSCADeT which is based on Morpho-spectral Component Analysis of multi-band images. The MuSCADeT algorithm takes advantage of the sparsity of astrono ...

Edp Sciences S A2016

Euclid: Early Release Observations – Programme overview and pipeline for compact- and diffuse-emission photometry

Jean-Paul Richard Kneib, Frédéric Courbin, Georges Meylan, Pascale Jablonka

The Euclid Early Release Observations (ERO) showcase Euclid’s capabilities in advance of its main mission by targeting 17 astronomical objects, including galaxy clusters, nearby galaxies, globular clusters, and star-forming regions. A total of 24 hours of ...

2025

Hopfield neural network deconvolution for weak lensing measurement

Frédéric Courbin, Georges Meylan, Malte Tewes, Guldariya Nurbaeva

Weak gravitational lensing has the potential to place tight constraints on the equation of the state of dark energy. However, this will only be possible if shear measurement methods can reach the required level of accuracy. We present a new method for meas ...

EDP Sciences2015

GREAT3 results - I. Systematic errors in shear estimation and the impact of real galaxy morphology

Frédéric Courbin, Malte Tewes, Huanyuan Shan, Marc Gentile, Thibault Adrien Kuntzer, Guldariya Nurbaeva

We present first results from the third GRavitational lEnsing Accuracy Testing (GREAT3) challenge, the third in a sequence of challenges for testing methods of inferring weak gravitational lensing shear distortions from simulated galaxy images. GREAT3 was ...

Oxford University Press2015

XXXIV. The effect of linear redshift-space distortions in photometric galaxy clustering and its cross-correlation with cosmic shear

Maurizio Martinelli, Frédéric Courbin, Georges Meylan, Malte Tewes, Slobodan Ilic, Gianluca Castignani, Alessandro Pezzotta

Context. The cosmological surveys that are planned for the current decade will provide us with unparalleled observations of the distribution of galaxies on cosmic scales, by means of which we can probe the underlying large-scale structure (LSS) of the Univ ...

Edp Sciences S A2024

Euclid preparation: XXXIX. The effect of baryons on the halo mass function

Frédéric Courbin, Georges Meylan

Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved.The Euclid photometric survey of galaxy clusters stands as a powerful cosmological tool, with the capacity to significantly propel our understand ...

2024

COSMOGRAIL XVII. Time delays for the quadruply imaged quasar PG 1115+080

Sun Hee Kim, Frédéric Courbin, Georges Meylan, Hung-Hsu Chan, Vivien François Bonvin, Malte Tewes, Martin Raoul Robert Millon, Karina Alexandra Rojas Olate, Eric Gérard Guy Paic

We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our results are based on almost daily observations for seven months at the ESO MPIA 2.2m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quas ...

EDP SCIENCES S A2018

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XV. Assessing the achievability and precision of time-delay measurements

Frédéric Courbin, Georges Meylan, Vivien François Bonvin, Malte Tewes, Thibault Adrien Kuntzer

COSMOGRAIL is a long-term photometric monitoring of gravitationally lensed quasars aimed at implementing Refsdal's time-delay method to measure cosmological parameters, in particular H-0. Given the long and well sampled light curves of strongly lensed quas ...

Edp Sciences S A2016

Euclid: Early Release Observations – Dwarf galaxies in the Perseus galaxy cluster

Frédéric Courbin, Georges Meylan, Pascale Jablonka

We make use of the unprecedented depth, spatial resolution, and field of view of the Euclid Early Release Observations (EROs) of the Perseus galaxy cluster to detect and characterise the dwarf galaxy population in this massive system. Using a dedicated ann ...

2025

Euclid preparation XLVI. The near-infrared background dipole experiment with Euclid

Frédéric Courbin, Georges Meylan

Verifying the fully kinematic nature of the long-known cosmic microwave background (CMB) dipole is of fundamental importance in cosmology. In the standard cosmological model with the Friedman–Lemaitre–Robertson–Walker (FLRW) metric from the inflationary ex ...

2024

Deep learning-based galaxy image deconvolution

Frédéric Courbin, Pascale Jablonka, Utsav Akhaury

With the onset of large-scale astronomical surveys capturing millions of images, there is an increasing need to develop fast and accurate deconvolution algorithms that generalize well to different images. A powerful and accessible deconvolution method woul ...

FRONTIERS MEDIA SA2022

Searching for Strong Gravitational Lenses

Frédéric Courbin, Cameron Alexander Campbell Lemon

Strong gravitational lenses provide unique laboratories for cosmological and astrophysical investigations, but they must first be discovered - a task that can be met with significant contamination by other astrophysical objects and asterisms. Here we revie ...

Springer2024

Euclid: Searching for pair-instability supernovae with the Deep Survey

Yi Wang, Frédéric Courbin, Georges Meylan, Giovanni Longo

Pair-instability supernovae are theorized supernovae that have not yet been observationally confirmed. They are predicted to exist in low-metallicity environments. Because overall metallicity becomes lower at higher redshifts, deep near-infrared transient ...

EDP SCIENCES S A2022

Disc colours in field and cluster spiral galaxies at 0.5 less than or similar to z less than or similar to 0.8

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

We present a detailed study of the colours of late-type galaxy discs for ten of the EDisCS galaxy clusters with 0.5 less than or similar to z less than or similar to 0.8. Our cluster sample contains 172 spiral galaxies, and our control sample is composed o ...

Edp Sciences S A2016

Strong lensing by edge-on galaxies in UNIONS

Frédéric Courbin, Cameron Alexander Campbell Lemon, Elodie Marie Charlène Savary, Javier Alejandro Acevedo Barroso

Current searches for galaxy-scale strong lenses focus on massive Luminous Red Galaxies but tend to overlook late-type lenses, in part because of their smaller Einstein radii. We take advantage of the superb seeing of the UNIONS survey in the r-band to perf ...

2024

Euclid II. The VIS instrument

Frédéric Courbin, Georges Meylan

This paper presents the specification, design, and development of the Visible Camera (VIS) on the European Space Agency’s Euclid mission. VIS is a large optical-band imager with a field of view of 0.54 deg2 sampled at 000 . 1 with an array of 609 Megapixel ...

2025

A Consistent Picture Emerges: A Compact X-Ray Continuum Emission Region In The Gravitationally Lensed Quasar Sdss J0924+0219

Frédéric Courbin, Georges Meylan, Malte Tewes

We analyze the optical, UV, and X-ray microlensing variability of the lensed quasar SDSS J0924+ 0219 using six epochs of Chandra data in two energy bands (spanning 0.4-8.0 keV, or 1-20 keV in the quasar rest frame), 10 epochs of F275W (rest-frame 1089 angs ...

American Astronomical Society2015

XVI. Measurement of the Hubble constant from the lensed quasar WGD 2038–4008

Frédéric Courbin

Time-delay cosmography is a powerful technique to constrain cosmological parameters, particularly the Hubble constant (H0). The TDCOSMO Collaboration is performing an ongoing analysis of lensed quasars to constrain cosmology using this method. In this work ...

2024

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

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

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