Astrophysics Seminar

Astrolunch: Jonathan Stern (MPIA)

Tue, 27/12/2016 - 12:30 to 13:30

Determining the acceleration mechanism of quasar-driven outflows and the thermal properties of circumgalactic gas
I will present two novel observational tests of astrophysical theories that are central to our understanding of galaxy evolution.

Astrolunch: Prof. Michael Gedalin (BGU)

Tue, 07/06/2016 - 12:30 to 13:30

TITLE: Collisionless relaxation in the shock front
ABSTRACT: The magnetic field profile of a collisionless shock is shaped mainly by ions. Upon crossing the shock ions begin to gyrate and form a non-gyrotropic distribution. The ion pressure tensor oscillates with the distance from the ramp. These oscillations damp due to collisionless gyrophase mixing. The latter is sensitive to the basic shock parameters. Chances to observe this relaxation are higher for shocks with lower upstream ion temperature.
‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts.

Special seminar: Dr. Biman Nath (Raman Research Institute)

Thu, 07/04/2016 - 12:30 to 13:30

Title: Outflows from galaxies: shocks and surprises
Biman Nath, Raman Research Institute, Bangalore, India
Abstract: Outflows from galaxies enrich the intergalactic medium and
play a crucial role in the evolution of galaxies. The standard scenario
of outflows from galaxies has been that of gas driven by thermal
pressure of the interstellar medium which is heated by multiple supernovae.
Recent observations of galactic outflows have shown that other
mechanisms such as radiation pressure and cosmic rays may also be

Astro seminar: Anastasia Fialkov (Harvard)

Sun, 07/01/2018 - 14:30 to 15:30

Title: Tracing cosmic dawn
The first billion years of cosmic history hold the key to unlocking many of the remaining mysteries in
astronomy, cosmology and physics. However, due to the lack of direct observations, we know almost
nothing about the objects (the first stars, galaxies, and quasars) that form at that time. Fortunately,
groundbreaking international projects that span the electromagnetic spectrum are soon to come on line, e.g.
the Square Kilometer Array (SKA; radio), the James Webb Space Telescope (JWST; infrared),

astrolunch: Ilya Gurwich (BGU)

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

Title - Modeling the Fermi Bubbles and Galactic Haze
Abstract -
We measure the spectrum of the Fermi bubble (FB) edges without the use of template reduction.
The edge spectrum exhibits a tilt compared to the bulk of the FBs, which we argue results from the diffusion of cosmic rays away from the edges and into the bubbles.
We also show that the FB edges can be observed not only in gamma-rays but in radio and X-rays as well.
Using these multi-messenger observations we identify the FB edges as a forward shock.