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“2015
Oskar Klein Memorial Lecture“
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Date: |
Download-files: |
Time: |
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Thursday, 04. Feb. 2016 |
Audio-only-Recording as MP3-File (smallest
possible size):
- Audio.mp3 (ca.32 Mb) ============================================ Video-Recording for any system with MP4-support:
- Video.mp4 (ca.292 Mb) |
15:15 – 16:25 |
Speaker :
Prof. Rashid Sunyaev (Director, Max-Planck-Institut für Astrophysik,
Garching)
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.