Publications by Frédéric Courbin

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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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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, ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

Frédéric Courbin

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

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

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

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

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

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

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

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

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

On the effect of image denoising on galaxy shape measurements

Cosmology From Gravitational Lens Time Delays And Planck Data

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

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

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

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

Euclid: Improving the efficiency of weak lensing shear bias calibration

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

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

Euclid preparation XXXVI. Modelling the weak lensing angular power spectrum

Euclid IV. The NISP Calibration Unit