Dr. Wei-Hao Wang (NRAO)

Submillimeter Galaxies at High and Low Redshifts 

Abstract

The far-IR/submillimeter (submm) extragalactic background light (EBL)
has an observed strength comparable to that of the optical/near-IR EBL,
implying that a complete picture of galaxy formation and evolution has
to include the submm emitting galaxies.  The main progress in this
field in the last decade came from radio identified, bright submm
sources; these are ultraluminous dusty galaxies at z~2-3.  However,
radio identified submm sources only account for at most ~20% of the
total submm EBL.  The rest of the submm EBL comes from faint submm
sources that are below the confusion limit of current single-dish submm
telescopes, and perhaps also from high-redshift submm sources that
cannot be identified with radio telescopes.  Our recent stacking
analyses in the GOODS-N show that the majority of the submm EBL comes
from a low-redshift, less luminous population at z~1.  This is a
redshift significantly lower than that of radio identified submm
sources.  We also find evidence of the existence of a z>4 submm
population.  The star formation rate density inferred from the submm
EBL at z=0-7 is 2 to 5 times higher than that derived from rest-frame
UV studies.