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OATS-DAUT SEMINAR
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Speaker: Antonaldo Diaferio (Univ. di Torino)

Title: Mass and Light in the Outskirts of Galaxy Clusters

Date: Wednesday, January 31st, 2007
Time: 12:00 noon
Venue: Villa Bazzoni

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Abstract:
Dark matter dominates the dynamics of cosmic structures. Quantifying the relative distribution of dark and luminous matter is a major challenge of modern cosmology. I will present the caustic technique, a method which uses the position and redshift of galaxies alone to measure the mass in the outer regions of clusters; here traditional methods, based on the assumption of dynamical equilibrium, do not hold. When applied to the CAIRNS survey and 72 more clusters extracted from the Sloan Digital Sky Survey (the CIRS survey), the caustic technique provides the largest sample of clusters whose mass profiles have been measured out to three times the virial radius. The universe matter density and the normalization of the power spectrum provided by the mass function of these clusters agree with the WMAP3 estimates. When combined with photometric and spectroscopic information, these cluster mass profiles can also provide relevant constraints on the models of galaxy formation in the transition region between the high-density cluster cores and the low-density field environment.
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