SEMINAR ANNOUNCEMENT - OAT and DAUT SEMINAR - Wedn. October 11, at 12:00 noon at Villa Bazzoni

[Gabriella Schiulaz]

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                 OATS-DAUT SEMINAR 
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Speaker: Santi Cassisi (INAF/Oss. Astr. Teramo) 

Title: The Helium abundance in Galactic Globular Clusters: 
some new -unexpected- results 

Date: Wednesday, October 11th, 2006 
Time: 12:00 noon 
Venue: Villa Bazzoni 

Abstract: 
We briefly review the methods for measuring the initial He abundance in stars belonging to galactic globular clusters based on stellar observables such as the "R" parameter and "A" one. We discuss the uncertainties affecting the theoretical calibrations of these methods and, show the comparison with empirical evidence. Some new - and unexpected - results obtained for omega Centauri, NGC2808 and the two twin clusters NGC6388 and NGC6441 are discussed. 
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Future Seminars 
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OATS-DAUT SEMINAR 
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Speaker: Carlotta Gruppioni (INAF/Oss. Astr. Bologna) 
Title: Title: Galaxy and AGN Evolution in the MIR: a combined Spitzer and X-ray view 

Date: Wednesday, October 18th, 2006 
Time: 14:30 (2:30 PM) 
Venue: Villa Bazzoni 

Abstract: 
A proper analysis of the evolution of sources emitting in the Mid-Infrared is strongly dependent on their broad-band spectral properties (SEDs) at different redshifts and luminosities and on a reliable classification allowing to disentangle AGN from star-formation activity. The diagnostic diagrams based on the optical line ratios are often ambiguous and/or misleading not allowing a proper separation of the galaxy/AGN populations. Thanks to the combination of deep X-ray and Spitzer a much better census of the hidden AGN activity and dust-obscured star-forming galaxies can be obtained. We show how to take advantage of the new X-ray and Spitzer survey data to constrain galaxy and AGN evolution, revising the results of previous phenomenological models. 


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OATS-DAUT SEMINAR 
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Speaker: Meg Urry (Yale University) 
Title: Supermassive Black Holes in Deep Surveys 

Date: Wednesday, October 25th, 2006 
Time: 11:00 
Venue: Villa Bazzoni 

Abstract: 
In principle, counting Active Galactic Nuclei (AGN) reveals the demographics of supermassive black holes. Optical/UV surveys easily find AGN out to high redshift, and they are numerous in the early Universe (z~2-3); however, if obscuration is important, as suggested by local AGN unification and by the spectrum of the X-ray background, the true number could be much larger. Using the deepest data from the Spitzer, Hubble, and Chandra Observatories, the Great Observatories Origins Deep Survey (GOODS) project reveals evidence for a substantial population of obscured AGN, with which we can explain the integrated X-ray background, the redshift distributions in deep X-ray surveys, and the infrared number counts of AGN. We can also directly estimate the AGN contribution to the extragalactic infrared background. With the larger-area MUSYC survey, we extend this work to higher luminosity AGN, and we report the discovery of new EXOs (Extreme X-ray Objects). Finally, combining all the large, deep, multiwavelength surveys, we find that the fraction of obscured AGN increases with redshift.

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OATS-DAUT SEMINAR 
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Speaker: Matteo Viel (INAF/Oss. Astron. di Trieste) 
Title: Strong MgII systems in quasar and gamma-ray burst spectra 
Date: Wednesday, November 8th, 2006 
Time: 12:00 noon 
Venue: Villa Bazzoni 
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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