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Frédéric Courbin

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Related publications (220)

Page 6 of 11

Euclid preparation: L. Calibration of the halo linear bias in Λ(v)CDM cosmologies

Frédéric Courbin, Georges Meylan

The Euclid mission, designed to map the geometry of the dark Universe, presents an unprecedented opportunity for advancing our understanding of the cosmos through its photometric galaxy cluster survey. Central to this endeavor is the accurate calibration o ...

2024

Euclid preparation XLVIII. The pre-launch Science Ground Segment simulation framework

Frédéric Courbin, Georges Meylan, Benjamin Yvan Alexandre Clement

Context. The European Space Agency’s Euclid mission is one of a raft of forthcoming large-scale cosmology surveys that will map the large-scale structure in the Universe with unprecedented precision. The mission will collect a vast amount of data that will ...

2024

Evaluating the effect of stellar multiplicity on the point spread function of space-based weak lensing surveys

Frédéric Courbin, Georges Meylan, Thibault Adrien Kuntzer

The next generation of space-based telescopes used for weak lensing surveys will require exquisite point spread function (PSF) determination. Previously negligible effects may become important in the reconstruction of the PSF, in part because of the improv ...

Edp Sciences S A2016

Nine lensed quasars and quasar pairs discovered through spatially extended variability in Pan-STARRS

Frédéric Courbin, Cameron Alexander Campbell Lemon, Aymeric Alexandre Galan, Frédéric Dux, Favio César Neira Diaz

We present the proof of concept of a method for finding strongly lensed quasars using their spatially extended photometric variability through difference imaging in cadenced imaging survey data. We applied the method to Pan-STARRS, starting with an initial ...

Edp Sciences S A2024

Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033-4723

Frédéric Courbin, Vivien François Bonvin

We present 13 seasons of R-band photometry of the quadruply lensed quasarWFI 2033-4723 from the 1.3m SMARTS telescope at CTIO and the 1.2m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of similar to 0.2mag on a timescale of ...

IOP PUBLISHING LTD2018

IX. Systematic comparison between lens modelling software programs:Time-delay prediction for WGD 2038-4008

Frédéric Courbin, Aymeric Alexandre Galan

The importance of alternative methods for measuring the Hubble constant, such as time-delay cosmography, is highlighted by the recent Hubble tension. It is paramount to thoroughly investigate and rule out systematic biases in all measurement methods before ...

EDP SCIENCES S A2022

Euclid: Cosmology forecasts from the void-galaxy cross-correlation function with reconstruction

Frédéric Courbin, Georges Meylan

We have investigated the cosmological constraints that can be expected from measurement of the cross-correlation of galaxies with cosmic voids identified in the Euclid spectroscopic survey, which will include spectroscopic information for tens of millions ...

EDP SCIENCES S A2023

Evolution of the observed Ly alpha luminosity function from z=6.5 to z=7.7: evidence for the epoch of reionization?

Jean-Paul Richard Kneib, Frédéric Courbin, Benjamin Yvan Alexandre Clement

Aims. Ly alpha emitters (LAEs) can be detected out to very high redshifts during the epoch of reionization. The evolution of the LAE luminosity function with redshift is a direct probe of the Ly alpha transmission of the intergalactic medium (IGM), and the ...

2012

The need for a multi-purpose, optical-NIR space facility after HST and JWST The case for an ESA-led HabEx Workhorse Camera

Frédéric Courbin

In the early 2030s, after the end of operations for the epochal Hubble Space Telescope and the long-anticipated James Webb Space Telescope, astrophysics will lose access to a general purpose high-spatial resolution space observatory to cover the UV-optical ...

SPRINGER2021

Deep optical spectroscopy of extended Ly alpha emission around three radio-quiet z=4.5 quasars

Frédéric Courbin, Pierre North, Alexander Patrick Eigenbrod

We report the first results of a spectroscopic search for Ly alpha envelopes around three z similar to 4.5 radio-quiet quasars. Our observational strategy adopts the FORS2 spectrograph mounted to the UT1 of the Very Large Telescope (VLT) in the multi-slit ...

2008

TDCOSMO: I. An exploration of systematic uncertainties in the inference of H-0 from time-delay cosmography

Frédéric Courbin, Hung-Hsu Chan, Martin Raoul Robert Millon, Aymeric Alexandre Galan

Time-delay cosmography of lensed quasars has achieved 2.4% precision on the measurement of the Hubble constant, H0. As part of an ongoing effort to uncover and control systematic uncertainties, we investigate three potential sources: 1- stellar kinematics, ...

EDP SCIENCES S A2020

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XII. Time delays of the doubly lensed quasars SDSS J1206+4332 and HS 2209+1914

Frédéric Courbin, Georges Meylan, Malte Tewes

Aims. Within the framework of the COSMOGRAIL collaboration we present 7- and 8.5-year-long light curves and time-delay estimates for two gravitationally lensed quasars: SDSS J1206+4332 and HS 2209+1914. Methods. We monitored these doubly lensed quasars in ...

Edp Sciences S A2013

Euclid: Early Release Observations – NISP-only sources and the search for luminous z = 6–8 galaxies

Frédéric Courbin, Georges Meylan

This paper presents a search for high redshift galaxies from the Euclid Early Release Observations program ‘Magnifying Lens.’ The 1.5 deg2 area covered by the twin Abell lensing cluster fields is comparable in size to the few other deep near-infrared surve ...

2025

On the effect of image denoising on galaxy shape measurements

Frédéric Courbin, Georges Meylan, Marc Gentile, Guldariya Nurbaeva

Weak gravitational lensing is a very sensitive way of measuring cosmological parameters, including dark energy, and of testing current theories of gravitation. In practice, this requires exquisite measurement of the shapes of billions of galaxies over larg ...

2011

Cosmology From Gravitational Lens Time Delays And Planck Data

Frédéric Courbin, Georges Meylan, Malte Tewes

Under the assumption of a flat Lambda CDM cosmology, recent data from the Planck satellite point toward a Hubble constant that is in tension with that measured by gravitational lens time delays and by the local distance ladder. Prosaically, this difference ...

Iop Publishing Ltd2014

Euclid: Early Release Observations – Globular clusters in the Fornax galaxy cluster, from dwarf galaxies to the intracluster field

Frédéric Courbin, Georges Meylan

We present an analysis of Euclid observations of a 0.6 deg2 field in the central region of the Fornax galaxy cluster that were acquired during the performance verification phase. With these data, we investigated the potential of Euclid to identify globular ...

2025

Euclid preparation: LVII. Observational expectations for redshift z < 7 active galactic nuclei in the Euclid Wide and Deep surveys

Frédéric Courbin, Georges Meylan

We forecast the expected population of active galactic nuclei (AGN) observable in the Euclid Wide Survey (EWS) and Euclid Deep Survey (EDS). Starting from an X-ray luminosity function (XLF), we generated volume-limited samples of the AGN expected in the Eu ...

2025

Shear measurement bias: I. Dependencies on methods, simulation parameters, and measured parameters

Frédéric Courbin, Marc Gentile

We present a study of the dependencies of shear bias on simulation (input) and measured (output) parameters, noise, point-spread function anisotropy, pixel size, and the model bias coming from two different and independent galaxy shape estimators. We used ...

EDP SCIENCES S A2020

HOLiCOW - IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology

Frédéric Courbin, Vivien François Bonvin

Strong gravitational lenses with measured time delays between the multiple images allow a direct measurement of the time-delay distance to the lens, and thus a measure of cosmological parameters, particularly the Hubble constant, H-0. We present a blind le ...

Oxford Univ Press2017

Euclid: Improving the efficiency of weak lensing shear bias calibration

Frédéric Courbin, Georges Meylan, Malte Tewes

To obtain an accurate cosmological inference from upcoming weak lensing surveys such as the one conducted by Euclid, the shear measurement requires calibration using galaxy image simulations. As it typically requires millions of simulated galaxy images and ...

Edp Sciences S A2024