SEMINAR ANNOUNCEMENT - OAT and DAUT SEMINAR - Wedn. November 15, at 12:00 noon (Villa Bazzoni)

[Gabriella Schiulaz]

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                 OAT - DAUT SEMINAR 
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Speaker: Enrico Maria Corsini (Univ. di Padova) 

Title: Direct measurements of bar pattern speed: implications for dark matter distribution and gas fueling in the center of barred galaxies 

Date: Wednesday, November 15th, 2006 
Time: 12:00 noon 
Venue: Villa Bazzoni (Via Bazzoni, 2)

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Abstract: 
The dynamics of a barred galaxy depends on the pattern speed of its bar. The only direct method for measuring the bar pattern speed is the Tremaine-Weinberg technique. This method is best suited to gas-poor galaxies and therefore it has been restricted to early-type barred galaxies. On the other hand, a variety of indirect methods, which are based on the analysis of the distribution and dynamics of the gaseous component, has been used to measure the bar pattern speed in late-type barred galaxies. Nearly all the measured bars are as rapidly rotating as they can be. By comparing these results with recent high-resolution N-body simulations of bars in cosmologically-motivated dark matter halos, it is possible to conclude that these bars are not located inside centrally-concentrated halos. The Tremaine-Weinberg technique also permitted us to establish directly that nested bars are rotating with different pattern speeds and, in particular, that the rotation frequency of the secondary bar is higher than that of the primary one. This makes double bars efficient agents in fueling the AGN activity. 
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Future Seminars 

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OATS-DAUT SEMINAR 
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Speaker: Simone Recchi (INAF/Oss. Astr. Trieste) 

Title: Early evolution of Tidal Dwarf Galaxies 

Date: Wednesday, November 22nd, 2006 
Time: 12:00 noon 
Venue: Villa Bazzoni 

Abstract: 
I will present a progress report of a project concerning the dynamical and chemical evolution of Tidal Dwarf Galaxies. Tidal tails, resulting from the interactions of large galaxies, can create self-gravitating structures which are the seeds of dwarf galaxies. In these galaxies, commonly known as Tidal Dwarf Galaxies , the Dark Matter content is very small, which make them more vulnerable to stellar feedback. Our first step is therefore to understand whether a model galaxy without Dark Matter can sustain the feedback of the ongoing star formation. We present tests of the evolution of models in which star formation efficiency, temperature threshold, initial distribution of gas and infall are varied. We conclude that it is feasible to keep a fraction of gas bound for several hundreds of Myr and that the development of galactic winds does not necessarily stop continuous star formation. At the end of my presentation I will briefly introduce a project concerning the self-enrichment of Globular Clusters. I shall summarize the chemical properties of Globular Clusters, focusing on the hints that some of the stars of the Globular Clusters are polluted by the ejecta released by older stars, probably of intermediate-mass, demonstrating therefore that Globular Clusters are not coeval objects. I will show the strategies and the first results adopted to sharpen our understanding on these issues. 


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OATS-DAUT SEMINAR 
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Speaker: Massimo Persic (INAF/Oss. Astr. Trieste) 

Title: Very-high-energy gamma-ray astrophysics with MAGIC: 
recent achievements and beyond 

Date: Wednesday, November 29th, 2007 
Time: 12:00 noon 
Venue: Villa Bazzoni 


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OATS-DAUT SEMINAR 
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Speaker: Fabio La Franca (Univ. di Roma Tre) 

Title: The evolution of active galactic nuclei 

Date: Wednesday, December 6th, 2006 
Time: 12:00 noon 
Venue: Villa Bazzoni 

Abstract: 
We will present the latest results on the cosmological evolution of the density of active galactic nuclei (AGNs) and of their NH distribution up to redshift 4. We used the HELLAS2XMM 2-10 keV X-ray sample combined with other published catalogs. Our best fit is obtained with a luminosity-dependent density evolution model where low-luminosity AGNs peak at z~0.7, while high-luminosity AGNs peak at z~2.0. There is evidence that the fraction of absorbed (NH>1022 cm-2) AGNs decreases with the intrinsic X-ray luminosity and increases with the redshift. Our results will be compared with the latest analyses on the density of AGN derived from mid-infrared surveys carried out with SPITZER. Using these data, we will present the estimate of the history of the density of supermassive black holes in the Universe. 
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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