Seminar Announcement -OATS-DAUT SEMINAR - Wednesday, Sept. 26th, at 12:00 noon (Villa Bazzoni)

[Gabriella Schiulaz]

I announce you this week's OAT-DAUT seminar:

*********************************************************** 
                 OATS-DAUT SEMINAR 
*********************************************************** 

Speaker: Luca Zappacosta (INAF/OATS) 

Title: Mass profiles of relaxed clusters of galaxies: an X-ray perspective 

Date: Wednesday, September 26th, 2007 
Time: 12:00 
Venue: Villa Bazzoni 


Abstract: The density profiles of Cold Dark Matter (CDM) simulated halos have long been modeled well by an NFW profile regardless of their mass. However recent higher resolution numerical simulations and simulations employing also the baryonic physics and feedback processes do not agree with an NFW parametrization especially in the cores. Regardless of the exact density parametrization, CDM simulations produce cosmological halos whose concentration parameters correlate with mass and redshift. These relations are expected to vary significantly as a function of cosmological parameters. I will present an X-ray observation of a very relaxed cluster of galaxies for which I will show that an NFW parametrization is still a good parametrization for cluster relaxed cores at least down to 0.015 of the virial radius and that baryons in these regions do not seem to have played a role in shaping the inner dark matter density profile. Moreover using XMM and Chandra X-ray observations of relaxed galaxy systems (from ellipticals to clusters) I will show that their concentration parameter significantly correlates with mass. I will discuss the agreement with simulations and show the potentially useful indications that can be derived for cosmological models. I will then present Chandra observations of a sample of 19 distant (out to z~1.1) relaxed galaxy clusters showing that the concentration parameter also correlates with redshift at levels in marginal agreement with the CDM predictions. 
*********************************************************** 




next week's seminar:
*********************************************************** 
                  OATS-DAUT SEMINAR 
*********************************************************** 
Speaker: Vincenzo Mainieri (ESO, Munich) 
Title: What can we learn on obscured AGN from the COSMOS Survey 

Date: Wednesday, October 3rd, 2007 
Time: 12:00 
Venue: Villa Bazzoni 
*********************************************************** 
Abstract: So far, a major challenge in tracking SBH growth at high redshift has been due to the fact that the growth phase of SBHs likely coincides with periods of high obscuration. It is extremely difficult to identify and follow up sufficiently large samples of such obscured AGN, since they are generally undetected at optical wavelengths. It is crucial to achieve a combination of wide area together with deep sensitivity in order to produce a complete sample of obscured AGN up to high redshift. The COSMOS survey is uniquely optimized to address this issue: it covers up to 2 squares degrees at X-ray, optical, IR and radio wavelengths. I will review the status of the different follow-up studies inside COSMOS relevant for this study, present the result of an X-ray spectral analysis on ~1000 X-ray selected AGN and discuss selection methods of obscured AGN using the Spitzer bands. 
*********************************************************** 


For additional information on scheduled OAT seminars see:
http://adlibitum.oats.inaf.it/seminari/

Gabriella Schiulaz
segreteria OAT
Phone: 040-3199241
schiulaz at oats.inaf.it
segreteria at oats.inaf.it