Observational Cosmology Group


Since 2005, a group at IFAE, together with a group at ICE (Institut de Ciències de l’Espai), and another at CIEMAT (Centro de Investigaciones Energéticas, Medio Ambientales y Tecnológicas) and Universidad Autónoma de Madrid (UAM), collaborates in the DES (Dark Energy Survey) international project, led by Fermilab (USA). In late 2016 the group joined the Large Survey Synoptic Telescope (LSST), led by SLAC (USA).

The main goal of this group is to study the origin, evolution, and fate of the universe, and shed light on the nature of dark energy. In 2005, IFAE joined the preparations for the Dark Energy Survey (DES), and designed and built most of the readout electronics of DECam, the DES camera. DES started taking data in 2012 and has now finished its observations. The group has concentrated its data analysis on weak gravitational lensing, potentially the most powerful probe of dark energy, achieving very high impact and leading key DES publications.

In 2017, IFAE PhD students led two “essential” papers that led to the “key” paper with the cosmological constraints from the first year of DES observations (DES-Y1). Then, in 2021, DES published the cosmological results from the first three years of observations (DES-Y3). IFAE (co-)led several projects, including the test and calibration of the measurements of the galaxy shapes for the weak lensing cosmological probe, the most crucial measurement in DES. During these years, members of the group have (co-)led the all-important photo-z working group, as well as 4 other groups. The group has held multiple leadership positions within DES, including the chairmanship of both the speakers’ bureau and the builders’ committee.

The group also led the construction, commissioning and operation of PAUCam, a novel narrow-band imager with quasi-spectroscopical resolution installed at the William Herschel Telescope (WHT) in La Palma in 2015. The group led several key publications of the PAU Survey (PAUS), demonstrating that PAUCam achieves the expected photo-z resolution. PAU, initially entirely Spanish, was later joined by 5 top European groups providing funding for operations. The group has held management positions also in PAUS (members of the Management board, Instrument Scientist, etc.)

The group is also well positioned to play an important role in the next generation of galaxy surveys: DESI, Euclid and LSST. IFAE designed, built and commissioned the 10 Guiding, Focusing and Alignment (GFA) cameras of the Dark Energy Spectroscopic Instrument (DESI), a Berkeley-led collaboration that started observations in 2021. A. Font-Ribera was recently awarded an ERC Consolidator Grant to lead the cosmological analysis of the Lyman alpha forest data in DESI; the ESA Euclid satellite mission, due to launch in July 2023, where IFAE led the development, construction and characterization of the Filter-Wheel Assembly (FWA); and the Dark Energy Science Collaboration (DESC) of the Legacy Survey of Space and Time (LSST) at the Vera Rubin Observatory.

The group is also well positioned to play an important role in the next generation of galaxy surveys: DESI, Euclid and LSST. IFAE designed, built and commissioned the 10 Guiding, Focusing and Alignment (GFA) cameras of the Dark Energy Spectroscopic Instrument (DESI), a Berkeley-led collaboration that started observations in 2021. A. Font-Ribera was recently awarded an ERC Consolidator Grant to lead the cosmological analysis of the Lyman alpha forest data in DESI. In the ESA Euclid satellite mission, due to launch in July 2023, IFAE led the development, construction and characterization of the Filter-Wheel Assembly (FWA). IFAE also participates in the Dark Energy Science Collaboration (DESC) of the Legacy Survey of Space and Time (LSST) at the Vera Rubin Observatory.