The 2015 Oskar Klein Memorial Lecture will be given by Professor Rashid Sunyaev of the Max Planck Institute for Astrophysics, Garching, who is also the recipient of the Oskar Klein Medal for 2015.
Professor Sunyaev has made groundbreaking contributions to theoretical astrophysics in the areas of cosmology, high-energy astrophysics and X-ray astronomy through his studies of some of the most extreme physical processes in the universe. His theory of the evolution of density fluctuations in the early universe (developed with Zel’dovich) predicted the acoustic peaks that are observed in the cosmic background radiation. He has also made key contributions to the theoretical description of matter accreting onto black holes, predicting a signature for the resulting X-ray emission.
Rashid Alievich Sunyaev received his PhD in astrophysics from Moscow University in 1968 and became a Professor at the Moscow Institute of Physics and Technology in 1974. He is a Director of the Max Planck Institute for Astrophysics in Garching, Germany and has been chief scientist at the Space Research Institute of the Russian Academy of Sciences since 1992.
The Oskar Klein Memorial lecture will take place at 3:15 PM on Thursday, February 4,
in the Oskar Klein Auditorium at the AlbaNova University Centre in Stockholm.
Title: “Unavoidable distortions in the spectrum of CMB and the Blackbody Photosphere
of our Universe”
Abstract: Spectral features in the CMB spectrum contain a wealth of information about physical processes in the early Universe at redshifts z < 2 10^6, i.e. when Universe was older than 2 months. The Cosmic Microwave Background Radiation (CMB) spectral distortions are complementary to other probes of cosmology. In fact, most of the information contained in the CMB spectrum is inaccessible by any other means. This talk outlines the main physics behind the spectral features in the CMB produced throughout the history of the Universe. I will concentrate on the distortions which are inevitable and must be present at the level observable by the next generation of CMB experiments. The spectral distortions considered here include spectral features from cosmological recombination of hydrogen and helium, resonant scattering of CMB by metals during reionization which allows us to measure their abundances, y-type spectral distortions produced during and after reionization and μ - type distortions created at redshifts z > 10^5 due to any significant energy release (for example: due to decay or annihilation of the dark matter particles or due to viscous decay of the primordial sound waves).
Special attention will be given to existence of the Blackbody Photosphere of our Universe at redshift z ~ 2 10^6, behind which Comptonization, double Compton and Bremsstrahlung are able to wash out any spectral distortions arising due to arbitrary strong energy release.
CMB spectral distortions detected on the sky by Planck spacecraft, South Pole Telescope and Atacama Cosmology Telescope permitted us to discover more than thousand unknown before clusters of galaxies (most massive gravitationally bound objects in the Universe, containing thousands of galaxies, hot (kTe > 1 KeV) intracluster gas, gravitational lenses and huge amount of dark matter). These clusters of galaxies are serving today as probes for modern cosmology tracing the growth of the Large Scale Structure with time and containing strong gravitational lenses.
If you want to know more, check also the official webpage for the Oskar Klein Memorial Lectures