Astrophysics Seminar

AstroLunch: Doron Chelouche

Tue, 24/01/2012 - 12:30 to 13:30

The Circum-Galactic Medium Around High-z Galaxies as Probed by Intervening Systems.
Despite some 40 years of research, the physical
nature of intervening absorption line systems remains
obscure. A brief review of the field will be given,
and recent advances in our phenomenological
understanding of intervening absorbers will be
outlined. New evidence that links star formation
activity and absorbers' phenomenology will be
presented, which sheds light on the physical nature

Astrolunch: Evgeny Derishev

Tue, 07/07/2015 - 12:30 to 13:30

TITLE: Phenomenological model of radiatively efficient relativistic shocks
ABSTRACT: We present a phenomenological model for emission from relativistic shocks. This model works best for those shocks, where dissipation of magnetic energy and radiative cooling of electrons take place on timescales shorter than the dynamical timescale.

Astrolunch: Nahum Arav (Virginia Tech)

Tue, 07/03/2017 - 12:30 to 13:30

Quasar outflows are situated thousands of times further from the
Super-massive black-hole than previously thought
Theoretical modelling tend to place quasar outflows at distances of
~0.01 pc. from the central source. Here we report the results of two
unbiased surveys targeting outflows that show troughs from S iv.
We find that at least 50% of quasar outflows are at distances larger
than 100 parsecs from the central source, and at least 12% are at
distances larger than 1000 parsecs. These results have profound

Astrolunch: Prof. Ari Laor (Technion)

Tue, 23/02/2016 - 12:30 to 13:30

Radiation Pressure Confinement
Photoionization models include the transfer of energy from the radiation to the illuminated matter, but often neglect the momentum transfer. This momentum transfer can determine the density structure of the photoionized gas, leading to a single solution. I will discuss the implications of this effect to the observed emission and absorption properties of Active Galactic Nuclei, and it’s possible relevance to various other systems.
‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts.