THE PLANCK COLLABORATION AWARDED BY THE GRUBER FOUNDATION
The Planck Collaboration received the prestigious Gruber Foundation Award, considered the “Nobel of Cosmology”. The project brought together more than 500 researchers and engineers from 25 scientific institutions in Europe and the United States. The results revolutionized our understanding of cosmology, and provided critical measurements in particle physics and on the Milky Way.
The Gruber Foundation prize jointly recognizes the mission's leaders, Reno Mandolesi (Istituto Nazionale di Astrofisica, Bologna, Italy, Head of the “Low Frequency Instrument”, LFI), Jean-Loup Puget (Institute for Space Astrophysics, associate researcher at the IAP, Head of the “High Frequency Instrument” (HFI), and all members of the Planck team. Earlier this year, the Planck collaboration was awarded the Royal Astronomical Society's “Group Achievement Award”.
Planck is an ESA space telescope developed in the early 1990s, and launched in 2009. Until 2013, it has been collecting microwave observations of the sky in 9 frequency bands by means of two instruments (LFI and HFI). These observations made it possible to reconstruct a map of the cosmic background radiation and its polarization, which can be considered as images of the Universe at its very first moments (http://public.planck.fr). Cosmologists consider these observations as “fossils” of the Big Bang (name given to the phenomenon that was the formation of the Universe). These maps have revolutionized our knowledge of cosmology, making it possible to place strong constraints on the formation models of the Universe and the physical processes involved. Thus, cosmologists have been able to validate the now “standard” model of a Universe in expansion after a very short period of “inflation” (a phase of extreme expansion). And its evolution appears now dominated by dark matter and dark energy, which future space missions will focus on characterizing (Euclid).
The observations obtained by Planck, and the measurements deduced therefrom, also contribute to the improvement of our knowledge of particle physics, in particular concerning the properties of neutrinos, as well as dark matter. Planck's maps also allow researchers to determine the ionization epoch of the Universe caused by the formation of the first stars (via their ultraviolet radiation emissions); as well as to refine the models of galaxies when they are creating large quantities of stars, thanks to the observation of their emissions in the far infrared, also captured by Planck. These observations have finally led to progress in the understanding of our galaxy, the Milky Way: as regards the distribution and the nature of the dust which fills it; by observing carbon monoxide emissions from galactic molecular clouds; by refining the measurements of the galactic magnetic field.
The Planck collaboration has already delivered three datasets to the scientific community: in 2011 (early delivery dedicated to astrophysics), in 2013 (data from the first year of observation, first delivery concerning "cosmological" measurements) and in 2015 (complete data and first delivery of polarization data of the magnetic field). The researchers in the collaboration are preparing a final delivery of the data, that will be available in 2018.
To date, the Planck collaboration has produced nearly 150 articles, representing several thousand pages of scientific results. Planck's data and the results presented in these articles have resulted in several thousands of scientific articles produced by the world astronomical community (the two most cited articles, which present the “cosmological” results deduced from the 2013 and 2015 deliveries, total more than 10 000 quotes).
France holds an important place in the Planck international collaboration (within Europe and the United States), with the responsibility for the realization of the HFI instrument and the processing of its data, as well as a very important financial and human support from CNES and the CNRS. The Institut d'astrophysique de Paris (IAP) played a key role in the Planck collaboration: the co-leader of the HFI instrument, François Bouchet, is a researcher of the laboratory which, under his leadership hosted the data processing center from HFI, as well as a team that has made a major contribution to the cosmological exploitation of the results. And, most bimonthly meetings over the last decade of the HFI Collaboration took place in the IAP amphitheater.
The IAP houses the reference computing infrastructures for HFI data reduction, and the construction of the sky maps in the microwave domain. In addition to the overall coordination, the IAP team is involved in many steps of this data reduction, including helping to improve the processing of polarization maps, or the preparation of simulations, which are essential for testing the data processing algorithms and characterize the quality of the results. During the analysis, the IAP staff occupied and still hold steering roles with respect to some of the key outcomes of the mission:
- the measurement of the properties and parameters of the cosmological model;
- the determination of the power spectrum of the background radiation and the reliability of the measured cosmological parameters;
- the determination of the time of ionization of the Universe, caused by the formation of the first stars;
- the measurement of deviations from a Gaussian distribution of fossil radiation fluctuations;
- the construction of a map of matter distribution in all the observable Universe, thanks to Planck observing of the effect of gravitational lensing of the background anisotropies by the large scale structures of the Universe;
- the construction of the map of fossil radiation corrected from astrophysical foregrounds.
The IAP researchers have already been recognised for their contributions to the sucess of Planck. Jean-Loup Puget (Institute for Space Astrophysics, associate researcher at the IAP) was awarded with the Shaw prize, considered the Nobel Prize for Asia. François Bouchet (IAP, CNRS), co-PI of HFI was awarded the Louis D grand Prize by the Academy in 2014, and the Émilie du Châtelet prize of the French Physical Society in 2016. Jean-François Cardoso (IAP, CNRS) was awarded the Paul Doistau-Emile Blutet prize from the Academy in 2013 and the silver medal of CNRS in 2014. Karim Benabed (IAP, Sorbonne Université) piloted the analysis and writing of the article rewarded by the La Recherche 2014 prize, in the Astrophysics category.
Figure 1: Part of the Planck/HFI team at the IAP in september 2013
Credit: Jean Mouette & François Bouchet
- François Bouchet
Institut d’astrophysique de Paris, CNRS, Sorbonne Université
bouchet [at] iap [dot] fr
- Karim Benabed
Institut d’astrophysique de Paris, CNRS, Sorbonne Université
benabed [at] iap [dot] fr
Web editing: Valérie de Lapparent
Layout: Jean Mouette