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Calendar of Physics Talks Vienna
| Dynamics of the Local Group in different theories of gravity |
| Speaker: | Christoph Saulder (Uni Wien) |
| Abstract: | The Local Group, our home galaxy group, consists of two large galaxies, the Milky Way and M31 (Andromeda Galaxy), and about 40 known galaxies. The starting point of the investigation is the observed distribution of the galaxies in the Local Group, which differs from our expectations. The problem is that most galaxies in our galaxy group are arranged in a quite thin plane which does not correspond to the disc-plane of one of the two dominant spiral galaxies. A possible explanation for the observed distribution is an interaction of the Milky Way and M31 about 10 to 12 Gigayears ago. At this time gas from outer parts of the galaxies has been scattered in the orbital plane of these two galaxies. It is investigated for which members of the Local Group this model is realistic and to reproduce the results of Sawa and Fujimoto in 2005. Since the orbits of dwarf galaxies around the host galaxies are sensitive to the shape of the host’s potential and to dynamical friction. So the dynamics of the Local Group are a perfect laboratory to test the Dark Matter paradigm and also an alternative theory, which is called MOdified Newtonian Dynamics (MOND). In this theory the law of gravitation is modified for small accelerations which occur in the outer parts of galactic discs and also in a galaxy group. In order to do this, stellar dynamical numerical simulations using newly developed software were run. The programmes were capable of performing n-body calculations with Newtonian gravity (and Dark Matter halos) or deep-MOND gravity, Hubble expansion and dynamical friction (only in the case of Newtonian gravity). The initial conditions of the models are optimised using a genetic algorithm until the distribution after the integration is sufficiently close to the observed distribution. The results are very multifarious, in some aspects also surprising and show that the model is possible in the case of Newtonian gravity but it has significant problems in MOND. |
| Date: | Tue, 12.10.2010 |
| Time: | 12:00 |
| Duration: | 60 min |
| Location: | TU Wien ( Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room E136 ) |
| Contact: | Niklas Johansson |
| Spectral Minimal Partitions |
| Speaker: | Thomas Hoffmann-Ostenhof (Univ.Wien) (Fakultät für Physik) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik |
| Date: | Tue, 12.10.2010 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | J. Yngvason |
| Helpful tools in finite group theory |
| Speaker: | Patrick Ludl (Univ.Wien) (Fakultät für Physik) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Tue, 12.10.2010 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | W. Grimus, H. Neufeld |
| Speaker: | Peter Krizan (Ljubljana University and J. Stefan Institute) |
| Abstract: | The seminar will first review some recent highlights of measurements of B and D meson properties that have been carried out by the Belle collaboration. We will discuss the motivation for a future Super B factory at KEK, as well as the requirements for the detector. Finally, the present status of the project will be presented together with the plans for the future. |
| Date: | Thu, 14.10.2010 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | SMI, Seminar room, Boltzmanngasse 3, 1090 Wien, Room 2.08 |
| Contact: | Roland Gsell |
| Spectral fits for the solar neutrino experiments BOREXINO and LENA |
| Speaker: | Felicitas Thorne (University of Technology, Munich/Germany) |
| Abstract: | The solar neutrino experiment BOREXINO, which is based on a 300 t liquid scintillator detector and detects neutrinos via neutrino-electron scattering, is located at the Laboratori Nazionali del Gran Sasso (LNGS). It was the first experiment to be able detecting solar neutrinos below 1 MeV.
The main focus of this talk is the challenging task of separating between background and neutrino recoil events in data analysis. While some background (i.e muons) can be tagged event-by-event, beta decay events cannot be distinguished from neutrino-electron scattering. Therefore neutrino spectra and beta decays have to be fitted simultaneously.
In this talk the approach of performing spectral fits and the current status of the work concerning reduction of the background (11C, 10C, 210Bi) to the pep/CNO neutrino search will be shown.
Furthermore this technique will be applicable in association with neutrino oscillometry in LENA (Low Energy Neutrino Astronomy), a next-generation neutrino experiment which is based on a 50 kton target of liquid scintillator.
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| Date: | Fri, 15.10.2010 |
| Time: | 14:00 |
| Location: | Institut für Hochenergiephysik, Nikolsdorfergasse 18, 1050 Wien, Bibliothek 1. Stock |
| Contact: | Ch. Schwanda |
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