Dear Colleagues

Today Wednesday, at 17:15, the Kolloquium series of SS05 will terminate with a talk on Astrophysics (see abstract below). From 16:45, there will be tea and coffee in front of the lecture hall 16 G 05 at the Irchel Campus of the University (the usual place!).

For directions or further information, go to

http://www.physik.unizh.ch/teaching/kolloquium05/kolloquium.html

Please note: There will be no talk in the last week of the semester.

With best regards,

Juerg Osterwalder

Gravitational Lenses, Hubble Constant, and QSOS

Georges Meylan Laboratoire d'Astrophysique, EPFL

In the context of the new scientific orientation of the Laboratory of Astrophysics of the EPFL, I will present three interconnected topics in extragalactic astrophysics: (i) COMOGRAIL is a photometric monitoring program of already known lensed quasars. Started in September 2004, it will provide, within 3 years, Ho determination with a precision better than 2%, including systematics. The project also involves VLT and HST follow up and the use of the most advanced image deconvolution softwares. (ii) Strong lensing can be efficiently used in the study (lensed) quasar accretion disk, by following the microlensing chromatic variations induced by the lensing galaxy. Our VLT spectrophotometric monitoring of the Einstein Cross is currently searching for chromatic microlensing events in order to constrain the energy distribution of the quasar accretion disk, at a resolution of a few micro, possibly even nano arcseconds. (iii) I will present the first results of a direct spectroscopic VLT and HST study of quasars hosts galaxies at low redshift (z<0.3).

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Prof. Dr. Jürg Osterwalder Physik-Institut, Universität Zürich Winterthurerstr. 190 CH-8057 Zürich, Switzerland phone: +41 44 635 5827 <<< NOTE NEW AREA CODE ! >>> lab: +41 44 635 5745 sekr: +41 44 635 5781 fax: +41 44 635 5704 e-mail: osterwal@physik.unizh.ch web: http://www.physik.unizh.ch/groups/grouposterwalder/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~