Université de GenèveDépartement de Physique ThéoriqueCAP Genève

Cosmic microwave background

The Cosmic Microwave Background (CMB) is due to the thermal photons remaining from the hot initial state of the Universe (commonly referred to as Big Bang). They have been emitted when the Universe became sufficiently cool so that neutral hydrogen could form. At this time, when the Universe was only about 380'000 years old (very little compared to its current age of 13.8 billion years in the standard model) the cosmic plasma became transparent to photons. The CMB is effectively a 'photograph' of the young Universe, showing the tiny fluctuations that are the seeds of the large-scale structure observed today. It is the most precious cosmological dataset for two reasons: Firstly, its anisotropies and soon also its polarization are measured with high precision, by the WMAP and Planck satellites. Secondly, we understand them well theoretically and can calculate them to good precision with cosmological perturbation theory. The combination of these two reasons means that we can use the CMB to estimate the parameters of the cosmological standard model and its variants, e.g. including primordial magnetic fields, to excellent precision (in cosmology this means a couple percent). According to the current understanding, the anisotropies and polarization of the CMB contain information about the earliest epoch of the Universe, inflation. Especially Non-Gaussianities in the distribution of these quantities can contain information about particle physics interactions at 1016 GeV, an energy about 12 orders of magnitude larger than what can be achieved the most powerful present particle physics accelerator, the LHC. A pedagogical introduction to the physics of the CMB is given on Wayne Hu's website.

Recent publications and presentations on this topic
Date: 3. July 2020
Members involved: Julien Carron
Topics: Cosmic microwave background
Type: Publication
Date: 30. June 2020
Members involved: Benjamin Bose, Lucas Lombriser
Topics: Cosmic microwave background, CMB lensing, Large-scale structure, Hubble constant
Type: Publication
Date: 15. August 2019
Members involved: Viraj Nistane, Giulia Cusin, Martin Kunz
Topics: Cosmic microwave background, inhomogeneous cosmology, CMB lensing, Large-scale structure
Type: Publication
Date: 2. August 2019
Members involved: Valerio De Luca, Gabriele Franciolini, Alexandros Kehagias, Antonio Riotto
Topics: Non-Gaussianity, Higher-spin, Cosmic microwave background
Type: Publication
Date: 6. January 2017
Members involved: Ruth Durrer
Topics: Cosmic microwave background, lensing, Large scale structure
Type: Publication
Date: 6. January 2017
Members involved: Ruth Durrer
Topics: Cosmic microwave background, cosmological parameters, Cosmological Perturbation Theory, lensing
Type: Publication
Date: 20. May 2016
Members involved: Ignacy Sawicki
Topics: Modified gravity, Dark energy, Cosmic microwave background, Large-scale structure, Code
Type: Publication
Date: 26. October 2015
Members involved: Subodh Patil
Topics: Cosmic microwave background, Inflation, gravity, Effective theories
Type: Publication
Date: 6. October 2015
Members involved: Vittorio Tansella, Ruth Durrer
Topics: Cosmic microwave background, lensing, Gravitational waves
Type: Publication
Date: 7. July 2015
Members involved: Martin Kunz, Savvas Nesseris, Ignacy Sawicki
Topics: Dark energy, Cosmic microwave background, lensing
Type: Publication



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