April 18
Abstract:
Jets from supermassive black holes are well known as extremely
powerful sources of panchromatic electromagnetic radiation.
They are notorious for their rapid variability-on a day timescale
or longer- at different wavelengths. Modern-era Cherenkov telescopes have shown that extragalactic
jets dominate the TeV sky. Most puzzling is the powerful, ultra-fast TeV
flaring, on a timescale of merely minutes that is observed
in an increasing number of blazar jets. This timescale is a factor of 100
shorter than the light-crossing time of the central black hole. Similar activity,
albeit less extreme is manifested by M87, a nearby radio galaxy.
In this talk, I will discuss the challenges that the TeV observations pose
to standard emission models and new ideas towards understanding these extreme flaring
events.