Publications de Benjamin Yvan Alexandre Clement

Euclid: A complete Einstein ring in NGC 6505

Georges Meylan, Frédéric Courbin, Benjamin Yvan Alexandre Clement

We report the discovery of a complete Einstein ring around the elliptical galaxy NGC 6505, at z = 0.042. This is the first strong gravitational lens discovered in Euclid and the first in an NGC object from any survey. The combination of the low redshift of ...

2025

Euclid: Searches for strong gravitational lenses using convolutional neural nets in Early Release Observations of the Perseus field

Georges Meylan, Benjamin Yvan Alexandre Clement

The Euclid Wide Survey (EWS) is predicted to find approximately 170 000 galaxy-galaxy strong lenses from its lifetime observation of 14 000 deg2 of the sky. Detecting this many lenses by visual inspection with professional astronomers and citizen scientist ...

2025

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

Georges Meylan, Frédéric Courbin, 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

Euclid preparation XXXIII. Characterization of convolutional neural networks for the identification of galaxy-galaxy strong-lensing events

Georges Meylan, Frédéric Courbin, Benjamin Yvan Alexandre Clement, Georgios Vernardos

Forthcoming imaging surveys will increase the number of known galaxy-scale strong lenses by several orders of magnitude. For this to happen, images of billions of galaxies will have to be inspected to identify potential candidates. In this context, deep-le ...

Edp Sciences S A2024

The impact of human expert visual inspection on the discovery of strong gravitational lenses

Frédéric Courbin, Elodie Marie Charlène Savary, Martin Raoul Robert Millon, Eric Gérard Guy Paic, Rémy Elie Joseph, Hung-Hsu Chan, Karina Alexandra Rojas Olate, Benjamin Yvan Alexandre Clement, Yue Pan

We investigate the ability of human 'expert' classifiers to identify strong gravitational lens candidates in Dark Energy Survey like imaging. We recruited a total of 55 people that completed more than 25 per cent of the project. During the classification t ...

OXFORD UNIV PRESS2023

A new step forward in realistic cluster lens mass modelling: analysis of Hubble Frontier Field Cluster Abell S1063 from joint lensing, X-ray, and galaxy kinematics data

Johan Richard, Jean-Paul Richard Kneib, Mathilde Jauzac, Benjamin Yvan Alexandre Clement, Benjamin Emmanuel Nicolas Beauchesne

We present a new method to simultaneously and self-consistently model the mass distribution of galaxy clusters that combines constraints from strong lensing features, X-ray emission, and galaxy kinematics measurements. We are able to successfully decompose ...

Oxford Univ Press2023

Probing the faint-end luminosity function of Lyman-alpha emitters at 3 < z < 7 behind 17 MUSE lensing clusters

Johan Richard, Benjamin Yvan Alexandre Clement

Context. This paper presents a study of the galaxy Lyman-alpha luminosity function (LF) using a large sample of 17 lensing clusters observed by the Multi Unit Spectroscopic Explorer (MUSE) at the ESO Very Large Telescope (VLT). The magnification resulting ...

Edp Sciences S A2023

Precision Modeling of JWST's First Cluster Lens SMACS J0723.3-7327*

Jean-Paul Richard Kneib, Benjamin Yvan Alexandre Clement, Benjamin Emmanuel Nicolas Beauchesne

Exploiting the fundamentally achromatic nature of gravitational lensing, we present a lens model for the massive galaxy cluster SMACS J0723.3-7323 (SMACS J0723; z = 0.388) that significantly improves upon earlier work. Building on strong-lensing constraint ...

IOP Publishing Ltd2023

Discovery of strongly lensed quasars in the Ultraviolet Near Infrared Optical Northern Survey (UNIONS)

Elodie Marie Charlène Savary, Martin Raoul Robert Millon, Eric Gérard Guy Paic, Hung-Hsu Chan, Karina Alexandra Rojas Olate, Benjamin Yvan Alexandre Clement, Cameron Alexander Campbell Lemon, Georgios Vernardos

We report the discovery of five new doubly imaged lensed quasars from the first 2500 square degrees of the ongoing Canada-France Imaging Survey (CFIS), which is a component of the Ultraviolet Near Infrared Optical Northern Survey. The systems are preselect ...

EDP SCIENCES S A2022

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

Frédéric Courbin, Elodie Marie Charlène Savary, Aymeric Alexandre Galan, Hung-Hsu Chan, Karina Alexandra Rojas Olate, Benjamin Yvan Alexandre Clement, Cameron Alexander Campbell Lemon, Georgios Vernardos

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 ...

EDP SCIENCES S A2022

Strong lensing in UNIONS: Toward a pipeline from discovery to modeling

Frédéric Courbin, Elodie Marie Charlène Savary, Hung-Hsu Chan, Karina Alexandra Rojas Olate, Benjamin Yvan Alexandre Clement, Cameron Alexander Campbell Lemon, Georgios Vernardos

We present a search for galaxy-scale strong gravitational lenses in the initial 2500 square degrees of the Canada-France Imaging Survey (CFIS). We designed a convolutional neural network (CNN) committee that we applied to a selection of 2 344 002 r-band im ...

EDP SCIENCES S A2022

An atlas of MUSE observations towards twelve massive lensing clusters

Jean-Paul Richard Kneib, Amélie Tamone, Andrei Variu, Benjamin Yvan Alexandre Clement

Context. Spectroscopic surveys of massive galaxy clusters reveal the properties of faint background galaxies thanks to the magnification provided by strong gravitational lensing.Aims. We present a systematic analysis of integral-field-spectroscopy observat ...

EDP SCIENCES S A2021

Improving parametric mass modelling of lensing clusters through a perturbative approach

Johan Richard, Jean-Paul Richard Kneib, Benjamin Yvan Alexandre Clement, Benjamin Emmanuel Nicolas Beauchesne

We present a new method to model the mass distribution of galaxy clusters that combines a parametric and a free-form approach to reconstruct cluster cores with strong lensing constraints. It aims at combining the advantages of both approaches, by keeping t ...

OXFORD UNIV PRESS2021

The BUFFALO HST Survey

Johan Richard, Céline Tchernin, Matthieu Schaller, Pascale Jablonka, Jean-Paul Richard Kneib, Huanyuan Shan, Hakim Atek, Richard Massey, David Richard Harvey, Mathilde Jauzac, Benjamin Yvan Alexandre Clement, Anja Von der Linden

The Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) is a 101 orbit + 101 parallel Cycle 25 Hubble Space Telescope (HST) Treasury program taking data from 2018 to 2020. BUFFALO will expand existing coverage of the Hubble Frontier Fields ...

IOP PUBLISHING LTD2020

A bright-lensed galaxy at z=5.4 with strong Ly alpha emission

Jean-Paul Richard Kneib, Benjamin Yvan Alexandre Clement

2018

Molecular gas properties of a lensed star-forming galaxy at z similar to 3.6: a case study

Johan Richard, Jean-Paul Richard Kneib, Benjamin Yvan Alexandre Clement

We report on the galaxy MACSJ0032-arc at z(CO) = 3.6314 discovered during the Herschel Lensing snapshot Survey of massive galaxy clusters, and strongly lensed by the cluster MACSJ0032.1+1808. The successful detections of its rest-frame ultraviolet (UV), op ...

Edp Sciences S A2017

Strong-lensing analysis of MACSJ0717.5+3745 from Hubble Frontier Fields observations: How well can the mass distribution be constrained?

Johan Richard, Jean-Paul Richard Kneib, Hakim Atek, Markus Rexroth, Mathilde Jauzac, Benjamin Yvan Alexandre Clement

We present a strong-lensing analysis of MACSJ0717.5+3745 (hereafter MACS J0717), based on the full depth of the Hubble Frontier Field (HFF) observations, which brings the number of multiply imaged systems to 61, ten of which have been spectroscopically con ...

Edp Sciences S A2016

Hubble Frontier Fields: predictions for the return of SN Refsdal with the MUSE and GMOS spectrographs

Johan Richard, Jean-Paul Richard Kneib, Hakim Atek, Richard Massey, Markus Rexroth, Mathilde Jauzac, Benjamin Yvan Alexandre Clement

We present a high-precision mass model of the galaxy cluster MACS J1149.6+ 2223, based on a strong gravitational lensing analysis of Hubble Space Telescope Frontier Fields (HFF) imaging data and spectroscopic follow-up with Gemini/Gemini Multi-Object Spect ...

Oxford Univ Press2016

[C II] emission in z similar to 6 strongly lensed, star-forming galaxies

Johan Richard, Jean-Paul Richard Kneib, Mathilde Jauzac, Benjamin Yvan Alexandre Clement

The far-infrared fine-structure line [C II] at 1900.5 GHz is known to be one of the brightest cooling lines in local galaxies, and therefore it has been suggested to be an efficient tracer for star formation in very high redshift galaxies. However, recent ...

Oxford Univ Press2016

The extraordinary amount of substructure in the Hubble Frontier Fields cluster Abell 2744

Johan Richard, Céline Tchernin, Jean-Paul Richard Kneib, Huanyuan Shan, Hakim Atek, Richard Massey, Markus Rexroth, David Richard Harvey, Mathilde Jauzac, Benjamin Yvan Alexandre Clement

We present a joint optical/X-ray analysis of the massive galaxy cluster Abell 2744 (z = 0.308). Our strong- and weak-lensing analysis within the central region of the cluster, i.e. at R < 1 Mpc from the brightest cluster galaxy, reveals eight substructures ...

Oxford Univ Press2016