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OATS-UNI/TS SEMINAR
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Speaker: Andrei Mesinger (Scuola Normale di Pisa)

Title: The formation of the earliest structures as a probe of Dark Matter and small-scale power
Date: Wednesday, May 22nd, 2013
Time: 11:30
Venue: Villa Bazzoni
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Abstract Warm Dark Matter (WDM) models have received renewed attention as an attractive solution for the apparent deficiencies of LCDM on small-scales. More fundamentally, current observations probe the density field directly only on scales larger than a few cMpc (corresponding to a mass scale of 1e13-1e14 Msun); measuring primordial power on smaller scales would be of great interest in both astrophysics and cosmology. The high-redshift Universe provides an excellent test-bed for such studies: since structure formation is hierarchal, the mere presence of objects at early epochs can strongly constrain models with limited small-scale power with little or no "gastrophysical" complications. I will discuss several such probes, including long-duration gamma ray bursts and the abundances of high-z lensed galaxies. Finally, I will motivate the upcoming observations of the redshifted 21cm line as a physics rich probe, which we can model using recently-developed semi-numerical simulations. Due to its sensitivity to the thermal history of the cosmic gas, the 21cm signal contains signatures of both WDM structure formation and heating from Cold Dark Matter annihilations, arising from the very first non-liear structures in our Universe.
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Contact: Matteo Viel (OATs)