Publications by Johan Richard | EPFL Graph Search

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

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

Revealing galaxy candidates out to z similar to 16 with JWST observations of the lensing cluster SMACS0723

Johan Richard, Jean-Paul Richard Kneib, Hakim Atek

One of the main goals of the JWST is to study the first galaxies in the Universe. We present a systematic photometric analysis of very distant galaxies in the first JWST deep field towards the massive lensing cluster SMACS0723. As a result, we report the d ...

OXFORD UNIV PRESS2023

Uncovering a population of gravitational lens galaxies with magnified standard candle SN Zwicky

Johan Richard, Johannes Richard Cornelis Geerit Kruis, Rémy Elie Joseph, Cameron Alexander Campbell Lemon

Detecting gravitationally lensed supernovae is among the biggest challenges in astronomy. It involves a combination of two very rare phenomena: catching the transient signal of a stellar explosion in a distant galaxy and observing it through a nearly perfe ...

NATURE PORTFOLIO2023

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

The core of the massive cluster merger MACS J0417.5-1154 as seen by VLT/MUSE

Johan Richard, Johannes Richard Cornelis Geerit Kruis, Jean-Paul Richard Kneib, Richard Massey, David Richard Harvey, Mathilde Jauzac

We present a multiwavelength analysis of the core of the massive galaxy cluster MACS J0417.5-1154 (z = 0.441). Our analysis takes advantage of Very Large Telescope/Multi-Unit Spectroscopic Explorer observations which allowthe spectroscopic confirmation of ...

OXFORD UNIV PRESS2019

Molecular clouds in the Cosmic Snake normal star-forming galaxy 8 billion years ago

Johan Richard, Daniel Pfenniger, Jean-Paul Richard Kneib

The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with 10(4)-10(7) solar masses (M-circle dot) and radii of 5-100 parsecs, are the seeds of star formation(1). Highlighting the mo ...

NATURE PUBLISHING GROUP2019

Dark matter dynamics in Abell 3827: new data consistent with standard cold dark matter

Johan Richard, Frédéric Courbin, Richard Massey, Rémy Elie Joseph, David Richard Harvey, Mathilde Jauzac

2018

Searching for supernovae in the multiply-imaged galaxies behind the gravitational telescope A370

Johan Richard, Jean-Paul Richard Kneib

2018

The extreme faint end of the UV luminosity function at z similar to 6 through gravitational telescopes: a comprehensive assessment of strong lensing uncertainties

Johan Richard, Jean-Paul Richard Kneib, Hakim Atek

2018

What if LIGO's gravitational wave detections are strongly lensed by massive galaxy clusters?

Johan Richard, Richard Massey, Mathilde Jauzac

2018

Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens

Johan Richard, Georges Meylan, Frédéric Courbin, Jean-Paul Richard Kneib, Mathilde Jauzac, Karina Alexandra Rojas Olate, Xin Wang, Adriano Agnello

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

Mapping substructure in the HST Frontier Fields cluster lenses and in cosmological simulations

Johan Richard, Jean-Paul Richard Kneib, Hakim Atek, Mathilde Jauzac, Cristina Popa

We map the lensing-inferred substructure in the first three clusters observed by the Hubble Space Telescope Frontier Fields (HSTFF) Initiative: Abell 2744 (z = 0.308), MACSJ 0416, (z = 0.396) and MACSJ 1149 (z = 0.543). Statistically resolving dark matter ...

Oxford Univ Press2017

A gravitationally boosted MUSE survey for emission-line galaxies at z greater than or similar to 5 behind the massive cluster RCS 0224

Johan Richard, Jean-Paul Richard Kneib, Richard Massey

We present a Very Large Telescope/Multi Unit Spectroscopic Explorer (MUSE) survey of lensed high-redshift galaxies behind the z = 0.77 cluster RCS 0224-0002. We study the detailed internal properties of a highly magnified (mu similar to 29) z = 4.88 galaxy ...

Oxford Univ Press2017

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

High-redshift supernova rates measured with the gravitational telescope A 1689

Johan Richard, Jean-Paul Richard Kneib

Aims. We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides. Methods. Our survey was based on multi-epoch J-b ...

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

The Bullet cluster at its best: weighing stars, gas, and dark matter

Johan Richard, Jean-Paul Richard Kneib, Danuta Janina Paraficz

Aims. We present a new strong lensing mass reconstruction of the Bullet cluster (1E 0657-56) at z = 0 : 296, based on WFC3 and ACS HST imaging and VLT/FORS2 spectroscopy. The strong lensing constraints underwent substantial revision compared to previously ...

Edp Sciences S A2016