Publications by Frédéric Courbin

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We present the first case of strong gravitational lensing by a QSO: SDSS J0013 + 1523 at z = 0.120. The discovery is the result of a systematic search for emission lines redshifted behind QSOs, among 22 298 spectra of the SDSS data release 7. Apart from th ...

Future data provided by the Euclid mission will allow us to better understand the cosmic history of the Universe. A metric of its performance is the figure-of-merit (FoM) of dark energy, usually estimated with Fisher forecasts. The expected FoM has previou ...

The GRavitational lEnsing Accuracy Testing 3 (GREAT3) challenge is the third in a series of image analysis challenges, with a goal of testing and facilitating the development of methods for analyzing astronomical images that will be used to measure weak gr ...

Planned wide-field weak lensing surveys are expected to reduce the statistical errors on the shear field to unprecedented levels. In contrast, systematic errors like those induced by the convolution with the point spread function (PSF) will not benefit fro ...

High-redshift binary quasars provide key insights into mergers and quasar activity, and are useful tools for probing the spatial kinematics and chemistry of galaxies along the line of sight. However, only three sub-10-kpc binaries have been confirmed above ...

We present our search for strong lens, galaxy-scale systems in the first data release of the Dark Energy Survey (DES), based on a color-selected parent sample of 18 745 029 luminous red galaxies (LRGs). We used a convolutional neural network (CNN) to grade ...

We present a new measurement of the Hubble Constant H-0 and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time delays. First, we measure the time delay of HE 0435-1223 from 13- ...

We study the intracluster light (ICL) and intracluster globular clusters (ICGCs) in the nearby Perseus cluster of galaxies using Euclid’s Early Release Observations. By modelling the isophotal and iso-density contours, we mapped the distributions and prope ...

The Euclid mission is expected to image millions of galaxies at high resolution, providing an extensive dataset with which to study galaxy evolution. Because galaxy morphology is both a fundamental parameter and one that is hard to determine for large samp ...

Gravitationally lensed quasars can be used to map the mass distribution in lensing galaxies and to estimate the Hubble constant H-0 by measuring the time delays between the quasar images. Here we report the measurement of two independent time delays in the ...

This work focusses on the pilot run of a simulation campaign aimed at investigating the spectroscopic capabilities of the Euclid NearInfrared Spectrometer and Photometer (NISP), in terms of continuum and emission line detection in the context of galaxy evo ...

The low-mass end of the stellar initial mass function (IMF) is constrained by focusing on the baryon-dominated central regions of strong lensing galaxies. We study in this Letter the Einstein Cross (Q2237+0305), a z = 0.04 barred galaxy whose bulge acts as ...

Strong gravitational lensing is a unique observational tool for studying the dark and luminous mass distribution both within and between galaxies. Given the presence of substructures, current strong lensing observations demand more complex mass models than ...

Measuring a weak gravitational lensing signal to the level required by the next generation of space-based surveys demands exquisite reconstruction of the point-spread function (PSF). However, unresolved binary stars can significantly distort the PSF shape. ...

The Euclid mission is generating a vast amount of imaging data in four broadband filters at a high angular resolution. This data will allow for the detailed study of mass, metallicity, and stellar populations across galaxies that will constrain their forma ...

Supernovae (SNe) that have been multiply imaged by gravitational lensing are rare and powerful probes for cosmology. Each detection is an opportunity to develop the critical tools and methodologies needed as the sample of lensed SNe increases by orders of ...

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 ...

Information on the spectral types of stars is of great interest in view of the exploitation of space-based imaging surveys. In this article, we investigate the classification of stars into spectral types using only the shape of their diffraction pattern in ...

We present the measurement of the Hubble constant, H-0, with three strong gravitational lens systems, We describe a blind analysis of both PG 1115+080 and 11E0435-1223 as well as an extension of our previous analysis of RXJ 1131-1231. For each lens, we com ...

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 ...

Frédéric Courbin

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First case of strong gravitational lensing by a QSO: SDSS J0013+1523 at z=0.120

Euclid preparation: XLVII. Improving cosmological constraints using a new multi-tracer method with the spectroscopic and photometric samples

The Third Gravitational Lensing Accuracy Testing (Great3) Challenge Handbook

Interpolating point spread function anisotropy

J1721+8842: a gravitationally lensed binary quasar with a proximate damped Lyman-alpha absorber

Search of strong lens systems in the Dark Energy Survey using convolutional neural networks

H0LiCOW-V. New COSMOGRAIL time delays of HE 0435-1223: H-0 to 3.8 per cent precision from strong lensing in a flat Lambda CDM model

Euclid: Early Release Observations – The intracluster light and intracluster globular clusters of the Perseus cluster

Euclid preparation XLIII. Measuring detailed galaxy morphologies for Euclid with machine learning

COSMOGRAIL: the COSmological MOnitoring of GRAvItational lenses - VII. Time delays and the Hubble constant from WFI J2033-4723

Euclid preparation XXX. Performance assessment of the NISP red grism through spectroscopic simulations for the wide and deep surveys

Constraining the low-mass end of the initial mass function with gravitational lensing

Modeling lens potentials with continuous neural fields in galaxy-scale strong lenses

Detecting unresolved binary stars in Euclid VIS images

Euclid preparation: LXVIII. Extracting physical parameters from galaxies with machine learning

LensWatch. I. Resolved HST Observations and Constraints on the Strongly Lensed Type Ia Supernova 2022qmx ("SN Zwicky")

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

Stellar classification from single-band imaging using machine learning

A SHARP view of H0LiCOW: H-0 from three time-delay gravitational lens systems with adaptive optics imaging

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