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


Researchers and Research professors

Engineers and Technicians

Post-doctoral fellows and CDD

PHD students

Thèses commencées en 2018
Sujet : Contraindre les propriétés des neutrinos avec la mission spatiale Euclid
PhD supervisor: Stéphanie Escoffier
Co-supervisor: William Gillard
Sujet : Deep Learning methods applied to large astrophysical imaging surveys
PhD supervisor: Dominique Fouchez
Thèses commencées en 2017
Sujet : Tester la cosmologie au delà du modèle standard à l'aide des grandes structures de l'univers et le satellite Euclid
PhD supervisor: Anne Ealet
Sujet : Contraintes cosmologiques avec les vides cosmiques dans eBOSS
PhD supervisor: Stéphanie Escoffier
Thèse commencée en 2015
Sujet : Traitement d'images astronomiques provenant de grands sondages photométriques du ciel pour la détection et la mesure d'objets transitoires
PhD supervisor: Dominique Fouchez
Co-supervisor: Marcella Hernandez
Voir les thèses précédentes (8)

Publications RENOIR


2018: 19 articles

  • Improving baryon acoustic oscillation measurement with the combination of cosmic voids and galaxies, C. Zhao et al. , arXiv:1802.03990
  • Measuring the Universe with galaxy redshift surveys, L. Guzzo et al. , arXiv:1803.10814 [astro-ph.CO]
  • Overview of the DESI Legacy Imaging Surveys, A. Dey et al. , DESI Collaboration, arXiv:1804.08657 [astro-ph.IM]
  • Multivariate analysis of cosmic void characteristics, M.-C. Cousinou et al. , arXiv:1805.07181 [astro-ph.CO]
  • Strong Dependence of Type Ia Supernova Standardization on the Local Specific Star Formation Rate, M. Rigault et al. , Nearby Supernova Factory Collaboration, arXiv:1806.03849 [astro-ph.CO]
  • On a quadratic equation of state and a universe mildly bouncing above the Planck temperature, J. Berteaud et al. , arXiv:1807.05068 [gr-qc]
  • Massive Neutrinos Leave Fingerprints on Cosmic Voids, C. D. Kreisch et al. , arXiv:1808.07464 [astro-ph.CO]
  • Cosmology and Fundamental Physics with the Euclid Satellite, L. Amendola et al. , arXiv:1606.00180 [astro-ph.CO]
  • The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Sky Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment, B. Abolfathi et al. , SDSS Collaboration, arXiv:1707.09322 [astro-ph.GA]
  • PTF11mnb: First analog of supernova 2005bf - Long-rising, double-peaked supernova Ic from a massive progenitor, F. Taddia et al. , arXiv:1709.08386
  • Euclid: Superluminous supernovae in the Deep Survey, C. Inserra et al. , Euclid Collaboration, arXiv:1710.09585
  • Preliminary measurement of the spherical proportional counter prototype, Z.-M. Wang et al. ,
  • The ESO's VLT Type Ia supernova spectral set of the final two years of SNLS, C. Balland et al. , SNLS Collaboration, arXiv:1712.07379 [astro-ph.GA]
  • Understanding Type Ia supernovae through their U-band spectra, J. Nordin et al. , SNFactory Collaboration, arXiv:1801.01834 [astro-ph.HE]
  • Gravitational birefringence and an exotic formula for redshifts, C. Duval et al. , arXiv:1802.09295 [astro-ph.CO]
  • Correcting for peculiar velocities of Type Ia Supernovae in clusters of galaxies, P.-F. Léget et al. , Nearby Supernova Factory Collaboration, arXiv:1804.03418 [astro-ph.CO]
  • Photometric redshifts from SDSS images using a convolutional neural network, J. Pasquet et al. , arXiv:1806.06607
  • The scale of cosmic homogeneity as a standard ruler, P. Ntelis et al. , arXiv:1810.09362
  • SNEMO: Improved Empirical Models for Type Ia Supernovae, C. Saunders et al. , Nearby Supernova Factory Collaboration, arXiv:1810.09476 [astro-ph.CO]

Conference proceedings

2018: 7 conference proceedings

  • Integration and testing of the DESI multi-object spectrograph: performance tests and results for the first unit out of ten, S. Perruchot, A. Ealet , A. Secroun , S. Escoffier , A. Le Van Su, J.-G. Cuby, M.-C. Cousinou , Proc. SPIE, High Energy, Optical, and Infrared Detectors for Astronomy VII (2018), Austin, Texas, United States, 10-15 Jun 2018
  • Euclid Near Infrared Spectrometer and Photometer instrument description frozen at the Critical Design Review, T. Maciaszek, A. Ealet , K. Jahnke, E. Prieto, R. Barbier, Y. Mellier, F. Beaumont, et al., Proc. SPIE, Space Telescopes and Instrumentation (2018), Austin, Texas, United States, 10-15 Jun 2018
  • Euclid: Homogeneity in the search of the Dark Sector, P. Ntelis , A. Ealet , indéfini, Rencontre de Moriond, Cosmology Session, March 2018 (2018), indéfini,
  • Detector chain calibration strategy for the Euclid Flight IR H2RGs, R. Barbier, S. Ferriol, B. Kubik, G. Smadja, A. Secroun , J.-C. Clémens , A. Ealet , W. Gillard , J. Zoubian , B. Serra , C. Rosset, R. Kohley, L. Conversi, F. Fornari, C. Buton, Proc. SPIE Int. Soc. Opt. Eng, 10709, SPIE Astronomical Telescopes + Instrumentation 2018 (2018) 107090S, Austin, United States, 10-15 Jun 2018
  • Euclid flight H2RG IR detectors: per pixel conversion gain from on-ground characterization for the Euclid NISP instrument, A. Secroun , J.-C. Clémens , A. Ealet , W. Gillard , B. Serra , J. Zoubian , R. Barbier, S. Ferriol, B. Kubik, C. Rosset, F. Fornari, R. Kohley, L. Conversi, C. Buton, G. Smadja, Proc. SPIE Int. Soc. Opt. Eng, 10709, SPIE Astronomical Telescopes + Instrumentation 2018 (2018) 1070921, Austin, United States, 10-15 Jun 2018
  • Random telegraph signal (RTS) in the Euclid IR H2RGs, R. Kohley, L. Conversi, P.-E. Crouzet, P. Strada, R. Barbier, S. Ferriol, B. Kubik, A. Secroun , J.-C. Clémens , A. Ealet , B. Serra , W. Gillard , C. Rosset, Proc. SPIE Int. Soc. Opt. Eng, 10709, SPIE Astronomical Telescopes + Instrumentation 2018 (2018) 107091G, Austin, United States, 10-15 Jun 2018
  • The Dark Side of Gravity and the Acceleration of the Universe, F. Henry-Couannier , PoS, EDSU2018, 2nd World Summit on Exploring the Dark Side of the Universe (2018) 047, Point a Pitre, France, 25-29 Jun 2018


2018: 1 report

  • Euclid NISP-S simulations for the Scientific Challenges #4, #5 & #6, T. Auphan , A. Ealet , N. Fourmanoit , S. Kermiche , D. Laugier , J. Zoubian , EUCL-CPP-TN-8-012

Complete list (PDF)
  • 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

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 will be launched in 2022 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, is involved in the preparation of the Euclid mission. The group is 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 is also in charge of calibrating the instrument before its delivery to ESA at the end of 2019.

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 2020. During the 10 years of its operating phase (2022-2032), 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 is responsible for coordinating the construction of the LSST filter changer system and for the construction of one of its subsystems: the auto-changer. Indeed, the camera's filter exchange system is composed of three automated systems: a carousel of 5 optical filters, a filter changer (the Auto Changer) which can, at any time, replace one of the 5 filters in place. The 6th filter can be interchanged in the camera during the day with a filter loading mechanism (the Loader). The system is validated by a test bench to simulate the actual camera configuration.

The team is working on the preparation of supernovæ analyses and photometric calibrations.

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)

Auto-Changer prototype, built at CPPM. © CPPM
Detection of a Supernova with LSST software on CFHT images. © CPPM