Dhruba Saikia (NCRA TIFR, Pune)

Radio galaxies: small and large - Dhruba Saikia Colloquium

ATNF Marsfield Lecture Theatre

Abstract

Radio galaxies and quasars, which are amongst the most
luminous and largest single objects in the Universe,
range in size from less than a few pc to over several
Mpc. They continue to pose a wide range of interesting
astrophysical questions. In this colloquium, we will
initially focus on the small sources which are of
sub-galactic dimensions, and explore possible evidence
of interactions with gas clouds via both total-intensity
and polarization observations. We discuss the HI properties
of these compact sources, and also examine whether these
are consistent with the unified scheme for radio galaxies
and quasars. One of the interesting questions related to
radio galaxies and quasars is whether their AGN activity
is episodic and if so, the range of times scales of such
activity. We discuss some of the physical properties of
large radio galaxies, focussing on those which show signs
of episodic activity.