XIIIth School of Cosmology
November 12 - 18, 2017IESC, Cargèse
The CMB from A to Z
promises and challenges of the CMB as a cosmological probe


Now that plank ends, the CMB community is turning to new, very ambitious projects over the next 20 years, with (as prime objectives) better constraints on the Physics of the primordial universe (including inflation). To do this, we try to measure the imprint of the primordial gravitational waves (on Mode B polarization), but also by tightening the constraints on the logarithmic slope of the spectrum of the primordial scalar fluctuations, as well as the possible deviations from such a power law. It is also matter to constrain the physics of neutrinos (number and mass), the best current constraints on the total mass of the three families of neutrinos are based on the CMB (<0.23 eV to 95% CL). Moreover, with the CMB as a source plane, it is possible to map the distribution of the dark matter (more than what is done for example with Euclid, which is very complementary for a tomographic approach). The necessary knowledge of foregrounds will also impressively improve the Physics of clusters of galaxies, by the detection of the Sunyaev-Zel'dovich effect in a very complementary way with the measurements of X-ray emission, as well as of that from the interstellar medium of our Galaxy, and mainly its magnetic field. There are also other projects to improve the knowledge of the black body spectrum by a factor of one thousand, by seeking expected distortions, with a richier Physics.

These scientific themes are based on the expected measures from the balloon projects (eg Bside in France, LSPE in Italy, SPIDER in the USA, UK and Canada), satellite projects (Lite for a launch in 2025, CORE + Proposed in M5 to ESA during the year for a launch in 2027-2028, the project PIXIE - Primordial Inflation Explorer - to measure the spectrum for a launch in 2022), plus all ground experiments (mainly in USA ACT, SPT, BICEP, CLASS, POLARBEAR / SImmons array, QUIJOTE, QUBIC, etc. in Europe), which are in the phase of deploying thousands of detectors on the sky with telescopes between 1 and 10mn. The next phase (planned), which aims to deploy some 500 000 detectors on the sky by 2025, will be worldwide and the European community will have to take a significant part in it.


  • The CMB landscape: past, present and future.
  • Understanding of measurement (detection technology, eg bolometers, implementation - cryogenics - overall design to mitigate systematic effects - in imaging - in spectroscopy - acquisition / redundancy strategy) and the basis of data processing to obtain maps and spectra.
  • Understanding of the sky (foreground contributions (synchrotron, free, AME, galaxy dust, clusters SZ, CIB, ...) and mathematical methods of analysis (including difficulties in estimating errors for nonparametric models).
  • Theoretical situation, understanding of observational signatures, and their practical use (likelihood, MC sampling, etc.)

Training goals

This school, which is open to international students, has as objectives the reciprocal upgrade and the development of a multidisciplinary community on the research lines promoted by the CNRS. It will favour the transfer of methods/techniques and the development of a multidisciplinary community that is either connected or interested in the massive data processing and statistical analysis. It will train new generations of researchers, notably on the basis of the existing Planck community. They will thus be able to take up the many challenges of all kinds that these ambitious projects involve, on theoretical aspects, instrumental ones and analysis of massive and complex data. The competencies (already obtained) in the processing of data are of interest to other scientific communities which have already expressed their interest, which will lead to the creation of networks for exchanges and collaborations.

    • The target population is made up of researchers working in the fields of cosmology, with a view to developing collaborations. Researchers from other communities, such as theoretical physics or high energy physics, may also be involved, especially those involved in data processing and analysis.
    • The school is also open to post-doctoral and doctoral students, so that they have advanced training, which will give them the opportunity to know each other and to be appreciated by their elders.

A Ph.D. degree in Astrophysics or Theoretical Physics is sufficient to benefit from this training.

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