München 2009 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 85: Gamma-Astronomie 4
T 85.4: Vortrag
Mittwoch, 11. März 2009, 17:30–17:45, M218
Connecting the early universe with VHE observations: first stars and the EBL — •Martin Raue1, Tanja Kneiske2, and Daniel Mazin3 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany — 3Institut de Fisica d’Altes Energies (IFAE), Edifici Cn. Universitat Autonoma de Barcelona, Barcelona, Spain
The end of the dark-ages of the universe - the epoch of reionization - is a one of the big open questions in cosmology. Reionization starts with the formation of the first stars (PopIII stars), which are believed to be hotter and (probably) more massive then the second generation stars. Their formation has been extensively studied via numerical simulations, but a direct detection is still pending. An indirect way to derive constraints on the parameters of the first stars is to connect them with present day observables. Emission from the first stars is expected to contribute to the density of the extragalactic background light (EBL) in the optical to near-infrared wavelength region. While difficult to access via direct measurements, limits on the EBL can be derived from observations of distant sources of very high energy (VHE) gamma-rays. Recently, strong constraints on the EBL in near-infrared have been derived. These limits are compared with model calculations for the EBL resulting from the first stars. Different parameters of the first stars (star formation rate, stellar initial mass function, metallicity) are probed and limits on these parameters are presented.