"Blobs" in blazar jets
  The concept of highly relativistic electrons confined to blobs that are
moving out with modestly relativistic speeds is often invoked to explain high
energy blazar observations. The important parameters in this model such as the
bulk Lorentz factor of the blob ($\Gamma$), the random Lorentz factor of the
electrons ($\gamma$) and the blob size are typically observationally
constrained, but its not clear how and why the energetic electrons are held
together as a blob. Here we present some preliminary ideas based on scenarios
for cosmic ray electron self-confinement that could lead to a coherent picture.
