Astronomy Tea Talks at Caltech

'Lyman-alpha Blobs: feedback or cooling?'

Lyman-alpha Blobs (LABs) are remarkable (but rare) objects:
100 kpc-scale line-emitting nebulae found at z>2. These objects
arouse curiosity because the extended Lya emission is predicted
to be a signature of the cold-mode cooling of gas onto growing
galaxies. But LABs are also associated with both AGN and starburst
activity. The feedback energy associated with these processes is
more than enough to power the Lya emission, and so there is some
controversy over which mechanism is at play. I will discuss the
LAB phenomenon, focusing on results from our deep Chandra survey
of the SSA22 protocluster (z=3.1) -- the richest association of
LABs known.