Renoir

The RENOIR team (Recherche Energie NOIRe) is a research team in cosmology whose goal is to answer the major open questions of modern cosmology. The main objective is to understand the recent acceleration of the expansion of the Universe. This acceleration of expansion is often associated with a mysterious dark energy that represents 70% of the universe's content. The study of dark energy is done by cosmological measurements based on cosmological probes (supernovae Ia, galaxies and cosmic voids).

The team is involved in several major cosmological surveys:

  • eBOSS/DESI where the CPPM develops cosmological tests on cosmic voids.
  • Euclid, an ESA space mission, where the team is responsible for characterizing the infrared detectors of the NISP spectro-photometer and developing an image simulator of this instrument used to prepare for data processing.
  • LSST, a future imager where the CPPM is in charge of the construction of the auto-changer of the filter exchange system and works in parallel with the preparation of supernovæ analyses and photometric calibrations.

More information available here

eBOSS - Credit eBOSS
Euclid - Credit Euclid
Credit LSST Project/NSF/AURA

Researchers and Research professors

Chaire of excellence

Engineers and Technicians

Post-doctoral fellows and CDD

PHD students

To determine the energy content of the Universe and measure its cosmic history, an observational method is to use Baryonic Acoustic Oscillations (BAO) as the standard scale in the spatial distribution of galaxies.

One of the challenges of BAO is the small amplitude of the signal, requiring the survey of huge cosmic volumes in order to obtain an accurate distance measurement. The BOSS survey, for Baryon Oscillation Spectroscopic Survey (Dawson et al. 2013), of SDSS-III (2009-2014) was part of this new generation of galaxy spectroscopic surveys, proposing to map the three-dimensional distribution of 1.5 million Luminous Red Galaxies (LRGs) located between 0.2 < z < 0.8 over a 10 000 deg2 view field. At the same time, BOSS probed the intergalactic medium (IGM) across the 160,000 quasars line of sight located between 2.3 < z < 2.8 using the Lyman-alpha (Ly-alpha) forest. The eBOSS project, for extended-BOSS (Dawson et al. 2016), succeeded BOSS in 2014. The goal of eBOSS, planned for 6 years until 2019, is to cover the entire domain in intermediate redshift, i.e. 0.6 < z < 3.5.

The group has been involved since 2010 in the study of emission line galaxies (ELG) in order to anticipate future surveys of distant galaxies that should cover the almost unexplored range of redshifts z>0.8. In order to improve our understanding of the nature of dark energy, we also participated in the application of a very promising new cosmological test, the Alcock-Paczynski (AP) test (Alcock et al. 1979). In particular we are interested in cosmic voids using the recent works of (Lavaux et al. 2012) who introduced the idea of extracting cosmological information from stacked cosmic voids.

The DESI (Dark Energy Spectroscopic Instrument) project (Aghamousa et al. 2016) consists of an innovative multi-object spectrograph (10 spectrographs with 3 spectral channels each), powered by 5000 optical fibers that can simultaneously produce 5000 galaxy spectra. The instruments will be installed on the 4-meter diameter Mayall telescope located in Arizona, USA, which has been dedicated to this project. In 2014, we obtained funding from AMIDEX (IDEX of Aix-Marseille University) in support of the DESI project in the context of a call for technology transfer. With this support we participate in the construction of the spectrographs that will be delivered to the project.

DESI will use the 4m Mayall telescope at Kitt Peak (©NOAO/AURA/NSF)
DESI will be composed of ten spectrometers, each equipped with 3 arms, a blue one (360 to 593nm), a red one (566 to 772 nm) and a near infrared one (747 to 980 nm)

Euclid is a space mission dedicated to the study of the acceleration of the Universe. Euclid launched on 1st july 2023 for a period of 6 years to study the large structures of the Universe over more than 15,000 square degrees up to a cosmic time of 10 billion year. The mission is optimized for two cosmological probes, the weak lensing and the galaxy clustering but will also address many other cosmological tests such as cluster measurements.

The CPPM, through the Renoir team, involved in the preparation of the Euclid mission. The group involved in the characterization and integration of near-infrared detectors of the NISP spectrophotometer, one of Euclid's two instruments. The H2RG detectors, delivered by NASA, have been characterized at the CPPM and are integrated into the focal plane of the NISP instrument. The CPPM was also in charge of calibrating the instrument before its delivery to ESA (at may 2020).

The second major involvement of the CPPM team concerns the Euclid ground segment (SGS). Ground segment is responsible for data processing and is distributed in the major European countries participating in the project. It is organized around operational units (OU), in charge of defining processing algorithms, and around Data Centers (SDC), in charge of implementing pipelines and producing catalogues. The CPPM is responsible for the development of the TIPS simulator (spectroscopic images of the NISP instrument), as well as its integration into the consortium's pipeline. The CPPM also participates in the production of simulations at the French SDC (CC-IN2P3).

At the science level, we participate in activities of the Galaxy Clustering Science Working Group (GC-SWG), we are leader of the Work-Package (WP) "New Probes", as well as of the SWG on transients/SNe. We are particularly involved in galaxy clustering analyses, cosmic voids, homogeneity scale and probe combination.

Mechanical model of the Euclid NISP instrument © CPPM
Demonstration model of the NI-DS detection system of the NISP instrument © CPPM

LSST is an 8 m ground-based telescope project that will cover the entire sky (20,000 deg²) in several photometric bands selected using colour filters. It will be built nearby the Gemini South (8.2 m) and SOAR (4.3 m) telescopes at the Cerro Pachón site. It is expected to provide its first images in 2023. During the 10 years of its operating phase (2023-2033), LSST will produce at least 10 times more data than the existing one. With one installation every 15 s, about 20 to 30 Terabytes per night are expected, for a total of about 30 Petabytes of data. Each installation covers 10 deg². The data will be reduced in two major mirror computing centers: the National Center for Supercomputing Applications (NCSA) in Illinois and the IN2P3 Computing Center.

The CPPM was responsible for coordinating the construction of the LSST filter-changing system for the prototype and the final model, as well as being responsible for building one of its sub-systems: the Auto Changer. The camera's filter exchange system is made up of three automated systems: a carousel of 5 optical filters, and a filter changer (the Auto Changer) that can replace any of the 5 filters in place at any time. The sixth filter can be interchanged in the camera during the day using a filter loader mechanism. The system has been validated on a test bench that simulates the camera's actual configuration. The scientific team is working on the preparation of supernova analyses and photometric calibrations. We are heavily involved in the use of data reduction software, where we are working to improve the algorithms and procedures for the discovery and photometric measurement of supernovae. We are using the expertise we acquired in this field over ten years ago with the SNLS collaboration and more recently with our participation in the Zwicky Transient Facility (ZTF) supernova cosmology programme to analyse nearby supernovae.

We are therefore strongly involved in the use of data reduction software and are working to improve algorithms and procedures for the discovery and photometric measurement of supernovae. We use the expertise acquired in this field with SNLS by using LSST software to reprocess SNLS images and reproduce a more complete Hubble diagram than the one published, not limiting ourselves to supernovae that have benefited from spectroscopic follow up.

The measurement of the Hubble diagram of supernovae is limited, already with current statistics, by systematic errors. In particular, photometric calibration will be a key point. We have therefore started an activity on photometric calibration. We focus on the use of external observations from the Gaia catalogue. We also have an experimental participation in the implementation of the DICE diode calibration project at OHP(obervatoire de haute provence)

Fine-tuning the LSST telescope filter changer - credit Patrick Dumas / CNRS Nucléaire & Particules
Prototype of the auto-exchanger, built at CPPM – credit CPPM
Close-up of the filter changer and CPPM engineers. During maintenance and qualification operations, the auto exchanger is extracted from the camera and positioned on its transport support. This makes it possible to work on the system in complete safety - credit Patrick Breugnon / CPPM
Close-up of the filter changer and camera. The auto-changer is housed in its transport bracket and is being installed in the camera - credit Patrick Breugnon / CPPM
View of the Vera Rubin Observatory on Cerro Pachón in Chile - credit Patrick Breugnon / CPPM
IN2P3 team posing in front of the LSST camera's U filter. The U filter is a perfect mirror in the visible range, since it only lets through UV radiation - credit Olivier Bonin / SLAC National Accelerator Laboratory
Detection of a supernova using LSST software on CFHT images - credit CPPM
PhD started in 2024
Subject: Contrôler les effets systématiques pour une cosmologie de précision avec les vides
Fundings: CNRS ERC Cosmobest
PhD director : Alice Pisani
Subject: Cosmologie avec les Supernovae du Zwicky Tansient Facility (ZTF) et de l'observatoire Rubin (LSST)
Fundings: Bourse AMU
PhD director : Benjamin Racine
Subject: Contraintes cosmologiques grâce aux vides cosmiques mesurés par les sondages modernes
Fundings: A*MIDEX COSMO-SP-VOIDS
PhD director : Alice Pisani
Subject: Réponse pixel non correlée et non biaisée des détecteurs NIR des missions Euclid et Svom
Fundings: CNRS/CNES
PhD director : Aurélia Secroun
Subject: Machine learning Approaches for image analysis in the Euclid/Nisp Instrument within de Anr Dispers framework
Fundings: CNRS - ANR Dispers
PhD director : Eric Kajfasz
Co-supervisor: Stéphane Ayache
PhD started in 2023
Subject: Preparation and Exploitation of Euclid Data for Gravitational Wave Cosmology
Fundings: Cotutelle IPhU/AMIDEX - La Sapienza (Italie)
PhD director : Eric Kajfasz
See old PhDs (23)

Articles

2026: 24 articles

2025: 102 articles

2024: 63 articles

Conference proceedings

2026: 5 conference proceedings

2024: 10 conference proceedings

Talks

2024: 8 talks

  • Experience with Winlight for Spectrographs, S. Escoffier, Spec-S5 Instrumentation Workshop, Chicago, United States, 27-29 Feb 2024
  • Status of the Euclid mission in flight, S. Escoffier, GDR CoPhy Annual meeting, Lyon, France, 21-23 May 2024
  • Unravelling Cosmology with Cosmic voids, A. Pisani, GDR CoPhy Annual meeting, Lyon, France, 21-23 May 2024
  • LSST: a unique survey set to start in one year, P. Antilogus, D. Fouchez, Tianguan International Research Project (IRP) meeting, Frejus, France, 7-9 Oct 2024
  • Dark Gravity confronted with Supernovae, Baryonic Oscillations and the Cosmic Microwave Background, F. Henry-Couannier, 17th Marcel Grossmann meeting, Pescara, Italy, 7-12 Jul 2024
  • Unravelling Cosmology with Cosmic voids, A. Pisani, New Strategies for Extracting Cosmology from Galaxy Surveys, 2nd edition, Sexten, Italy, 3 Jul 2024
  • Cosmological Surveys: What They Reveal About the Universe, S. Escoffier, Tianguan International Research Project (IRP) meeting, Frejus, France, 7-9 Oct 2024
  • Unravelling Cosmology with Cosmic voids, A. Pisani, Joint Astrophysics Colloquium at ESO, Munich, Allemagne, 11 Nov 2024

Posters

2024: 1 poster

  • SN Ia and large-scale structure: voids, clusters and peculiar velocities, D. Rosselli, 58th rencontre de Moriond - Cosmology, La Thuile, Italy, 31 Mar - 7 Apr 2024

Reports

PhD theses or HDR

2025: 4 phd theses or hdr

  • Cosmological constraints by tomographic galaxy clustering with Euclid data, Vincent Duret, Aix-Marseille Université, 13 Mar 2025
  • Large-Scale Structure Cosmology : A Joint-Space Approach to Redshift-Space Distortions and Low-Redshift Clustering Probes, V. Aronica, Aix-Marseille Université, 15 Sep 2025
  • Low-redshift type Ia supernovae as tracers of the velocity field to measure the growth rate of cosmic structures with LSST, D. Rosselli, Aix-Marseille Université, 25 Sep 2025
  • Cosmic voids in modern Cosmology: from CMB lensing cross-correlations to dynamical void identification, S. Sartori, Aix-Marseille Université, 13 Nov 2025

2024: 3 phd theses or hdr

  • Advancements towards precision cosmology with Void-Lensing: Observational aspects and modeling, R. Isquierdo Boschetti, Aix-Marseille Université, 06 Fev 2024
  • Des échelles linéaires aux échelles non linéaires : analyse du regroupement des galaxies et des vitesses particulières pour contraindre l’énergie noire, Dumerchat, T., Aix-Marseille Université, 15 Oct 2024
  • Modélisation avancée de la réponse pixel des détecteurs CMOS : décorrélation des paramètres et application à Euclid et SVOM, J. Le Graet, Aix-Marseille Université, 30 Oct 2024
  • LSST: on May 15, 2018, the prototype of the filter changer system, one of the main components of the LSST camera, was inaugurated. This technical feat is the result of collaboration between five CNRS IN2P3 laboratories.In this unique project, France plays a very special role alongside the United States and Chile.
LSST filter exchanger © CPPM
Transport of the LSST filter exchanger © CPPM
  • Euclid: CPPM had just completed the characterization of the 16 flight detectors of the Euclid NISP. Twenty flight detectors, selected by NASA, were delivered to the CPPM, characterized in our clean rooms in 2017-2018. They will be integrated on the NISP instrument in 2019, at LAM (Laboratoire d'Astrophysique de Marseille), with which the CPPM is working closely.
Characterization testbenches for the infrared detectors of the NISP instrument of the Euclid space mission. The flight detectors are tested for 45 days under vacuum at -200°C with a view to evaluate their performance © C.Moirenc
Integration of a Euclid infrared detector for its characterization. This work takes place within an ISO5 environment in a clean room (less than 100 particles of dust per m3) © C.Moirenc
Infrared detector on its transporting stand. This detector is manufactured by the American company Teledyne and characterized at CPPM for the Euclid space mission. © C.Moirenc