The COSMO-ML team is involved in several major cosmology projects.
1) NIKA2
This is a camera based on arrays of KIDs (Kinetic Inductance Detectors) for observations in the millimeter range with IRAM 30-m telescope. The camera was designed and built by the NIKA2 collaboration with ANR funding. The LPSC was heavily involved in the construction of NIKA2, taking charge of the electronics and commissioning. NIKA2 has two frequency bands (1.2 and 2 millimeters) and thousands of KIDs. It is a unique instrument for continuum observations in the millimeter range. The NIKA2 collaboration obtained 1300 hours of guaranteed time from IRAM, spread over 5 Large programs. The LPSC has taken charge of the Sunyaev Zel'dovich (SZ) large observing program dedicated to cosmology with galaxy clusters. This program consists of resolved SZ observations of 35 clusters, at redshifts between 0.5 and 0.9, selected from the Planck and ACT catalogs. It is a key element in the measurement of the scaling relationship between cluster mass and SZ observable, which is crucial for galaxy cluster cosmology. We also took charge of building the polarization measurement system, which we are using to calibrate future CMB polarization experiments aimed at measuring the primordial B modes associated with inflation.
Mone information on NIKA2 activities at LPSC : CLICK
2) KISS & Concerto
The LPSC, as part of the GIS-KIDS, has been a driving force in the development of KIDS-based ground-based millimeter spectro-imagers via Martin-Pupplet Interferometer (MPI) type interferometers. KISS, which was installed at the QUIJOTE telescope at the Teide Observatory in Tenerife from late 2018 to 2020, was a prototype experiment. The instrument was designed and built as part of GIS-KIDS, with leadership from LPSC and a very strong contribution from LPSC technical departments (mechanics, instrumentation, electronics). The CONCERTO (CarbON CII line in post-rEionisation and Reio- nisaTiOn) instrument, which was operated at the APEX telescope at 5000 m in Chile, was built with ERC senior funding in collaboration with the LAM. CONCERTO uses 2 arrays of 2172 detectors each, corresponding to a focal plane of 18.6 arc-minutes diameter, in the spectral range 130 to 310 GHz, with a maximum spectral resolution of 1.8 GHz. LPSC was responsible for the optical design, as well as the design and manufacture of the electronics and acquisition system. CONCERTO operated successfully between April 2021 and May 2023. COSMO-ML members regularly took part in the observation and maintenance campaigns. These made it possible to carry out observations of the large-scale program on line intensity mapping [CII] for 1300 hours in the COSMOS field. In addition, the LPSC has driven and supported SZ spectrum observations for around 300 hours in 5 galaxy clusters. At present, we are heavily involved in the development of the spectroscopy pipeline and in the exploitation of SZ data from galaxy clusters, for the measurement of their mass, temperature and velocity.
3) Euclid
This ESA satellite mission, launched at Lagrange point L2 in July 2023, will investigate visible and infrared cosmology via weak gravitational lensing, galaxy clustering and galaxy clusters. With two state-of-the-art instruments - the VIS visible imager and the NISP infrared spectrometer - and extensive sky coverage, Euclid will be a major cosmology experiment for decades to come. The COSMO-ML team has been heavily involved in characterizing NISP, taking charge of electromagnetic compatibility tests on detectors and calibration sources. We are currently heavily involved in the analysis of Euclid data within the Science Ground Segment. In this context, we are responsible for internal data analysis and the construction of masks for observing properties, instrument and sky brightness. Spatial variations in the latter can give rise to systematic effects in galaxy detection. We are working on algorithms to correct the 3x2-pts correlation function and the galaxy cluster detection function for these effects. We are also participating in the SWG lensing and galaxy clustering project to study systematic effects in the estimation of cosmological parameters.
4) Instrumental activities (millimetric room)
The LPSC, Institut Néel, IPAG and IRAM laboratories are driving the development of the new generation of cryogenic KID detectors (Kinetic Inductance Detectors) as part of the Groupe d'Intérêt Scientifique (GIS) KIDs. The latter aims to ensure and enhance the visibility of the collaboration's activities. The scope of the GIS KIDs includes the manufacture and photometric validation of KIDs, cryogenics, the readout and acquisition system, ancillary instrumentation and scientific calibration. The COSMO-ML group and its electronics, mechanics and SDI departments play a key role in the development of the readout system and acquisition software, the design and manufacture of the pick-up optics, and detector characterization measurements. In 2021, we strengthened the activities of the GIS KIDs by equipping a new millimeter laboratory at the LPSC. This has been installed in the laboratory's project hall and operates in parallel with that of the Institut Néel. The millimeter room is designed around the KISS instrument, which has been repatriated to Grenoble and modified for laboratory measurement constraints. The KISS instrument is complemented by a range of state-of-the-art equipment, including a test bench for reading electronics, an acquisition computer network, a sky simulator and a pointing table for simulating astrophysical observations, as well as a polarization modulation and measurement system.
5) ERC RadioforegroundsPlus
This is a HORIZON-CL4-2023-SPACE-01 project, in which the team is co-PI, aimed at the precise characterization of polarization emissions from dust and the galactic synchrotron, so as to be able to reduce their contamination in the measurement of CMB polarization anisotropies and in particular primordial B modes. This project follows on from the ERC H2020 COMPET-5 RADIOFOREGROUNDS in which the team was also co-PI. This project resulted in the delivery of a public code for modeling the Galactic magnetic field and polarization foreground emission.
6) LiteBIRD
LiteBIRD is a new-generation satellite experiment by JAXA, NASA and ESA, scheduled for launch in 2033. Its aim is to measure the polarization anisotropies of the Cosmic Microwave Background, and in particular the B-modes due to primordial gravitational waves. The experiment features unprecedented frequency coverage, with 14 frequency bands between 34 and 448 GHz, and exquisite sensitivity, with 3 instruments: LFI, MFI and HFI. It will provide the most precise measurement of inflationary energy, opening the door to the physics of the primordial Universe. The team is responsible for ground characterization of polarization measurements with the medium- and high-frequency instruments. We are also involved in the preparation of data analysis, particularly in terms of in-flight calibration and the correction of systematic effects. We are also involved in physics studies, including the measurement of the SZ effect and polarization foreground emissions. Understanding the latter will be fundamental to achieving cosmological objectives.
7) SO
The Simons Observatory (SO) experiment, designed to measure the temperature and polarization anisotropies of the CMB with unrivalled precision, is currently being set up in the Atacama desert in Chile. With six SAT (small aperture telescope) and one LAT (large aperture telescope) instruments, SO will enable both the study of the CMB's primordial polarization B modes and the mapping of matter in the Universe thanks to the gravitational lensing effect and the SZ effect. This is both a project with great scientific potential in our group's field of interest, and a luxury pathfinder for new-generation instruments like CMB-S4. As part of the CNRS AAR call for projects, we are proposing to build and equip a SAT with a new instrument based on the KID technology developed by GIS-KID in Grenoble. In terms of polarization measurement, we plan to use technology similar to that used by NIKA and NIKA2. Aiming for an instrument observing at high frequencies (above 200 GHz) and thanks to KID technology, we could make a significant contribution to SO through: 1) better focal plane coverage, 2) redundancy for subtracting atmospheric contamination, and 3) a stronger frequency lever to reduce the contribution of galactic dust to the CMB's primordial B modes. Assuming funding in 2024, it is realistic to envisage an installation in the second phase of operation (Advanced SO). We also want to focus on cosmological analyses of gravitational lensing and galaxy clusters. These analyses have strong links with our current work at the LPSZ and will provide a springboard for our participation in CMB-S4 and LiteBIRD.
8) CMB-S4
CMB-S4 is the next-generation ground-based CMB experiment, which, with 0.5 million detectors covering a frequency range from 20 to 300 GHz, will measure CMB temperature and polarization with unprecedented precision. Its ambitious scientific program covers the search for primordial B-modes signalling inflation, the search for new relic particles, the determination of the neutrino mass hierarchy, the understanding of structure formation and the study of the transient universe. The experiment, which includes 3 0.6 m diameter SATs and a 5 m diameter LAT installed at the South Pole, as well as 2 6 m LATs in the Atacama desert, is scheduled for construction in 2026, with first light in 2032. The team and technical services are already engaged in the development of the ambient-temperature reading electronics and in the project's data management. We're aiming to make a major contribution to the reconstruction of the gravitational lensing effect, and to cosmology with thermal and kinetic SZ effects.
9) Past team projects
- NIKA :
The NIKA camera, also built and designed by the NIKA2 collaboration with a major contribution from LPSC. Its field of view was smaller (1.8 arcmin) due to the reduced number of detectors (356). It was used at IRAM's 30-meter telescope from 2012 to 2015.
In this context, we observed a sample of six SZ clusters. With NIKA, we performed the first SZ mapping with a KID-based camera [R. Adam et al., A&A 2014]. The observation of MACS cluster J0717.5 + 3745 allowed us to publish two major results: the first model-independent mapping of the kinetic Sunyaev-Zel'dovich effect [R. Adam et al., A&A 2017a] as well as the first temperature map obtained by combining X-ray and SZ data [R. Adam et al., A&A 2017b]. In [F. Ruppin et al., A&A 2017], we proposed a new procedure for non-parametric deprojection of the electronic pressure of the intracluster medium, from the core of the cluster to its peripheral regions. The full data set from this pilot sample has been made public.
NIKA has also enabled us to make high-quality polarization observations. We designed and built the polarization modulator based on a rotating half-wave plate. In addition, the polarized data processing pipeline was developed in collaboration with the IPAG team. This enabled us to obtain the first scientific results in polarization with arrays of KIDs [A. Ritacco et al., A&A 2017, 2018].
The Planck satellite, dedicated to the study of the temperature and polarization anisotropies of the Cosmic Microwave Background (CMB), has been one of the flagship instruments of modern cosmology over the past decade, and its results set the standard for the community. Planck, which was successfully launched on May 14, 2009 at 13:12 UTC, was located 1.5 million km from Earth (at Lagrange point L2). It consisted of two instruments, High Frequency Instrument and Low Frequency Instrument, placed at the focus of a 1.2 m telescope with very wide frequency coverage, from 30 to 857 GHz, with detectors limited by photon noise.
After being heavily involved in the design and manufacture of the control electronics for the 20 K (sorption cooler) and 0.1 K stages, the team turned its attention to data analysis on the HFI instrument. In particular, the team was responsible for the analysis of time-ordered data and systematic effects in polarization maps due to intensity leakage. The team has been heavily involved in measuring the polarization anisotropies of the CMB, as well as in reconstructing the gravitational lensing effect on the CMB and compiling a catalog of galaxy clusters detected via the SZ effect. In this context, we were responsible for the delivery of several products of interest to cosmology, including the SZ effect map, the map of areas of strong CO line emission and the map of the lensing-induced polarization B mode. We also took part in analyses of Galactic foreground emission. Members of our team were members of the Planck Core Team and appointed Planck scientists. We have signed all Planck papers for the 2013, 2015 and 2018 cosmological deliveries. We were also responsible for some of these papers.
The project, which has now been completed, was both a formidable test bed for the Planck-HFI instrument and a scientific success in terms of measuring the temperature anisotropies of the Cosmic Microwave Background and studying foreground emission.
