Kurt Adelberger

Caltech

Star Formation and Structure Formation at 1<z<3

Although there has been tremendous theoretical progress in understanding
the evolving distributions of dark matter and of gas at high redshift,
star formation and galaxy formation have proved far more difficult
to model.  Empirical constraints on where star formation occurs   
at high redshift are desperately needed.  Color-selected redshift 
surveys, designed to isolate galaxies in a narrow redshift shell  
from the dominant foreground and background populations in deep
optical images, provide an efficient way to build large samples
of galaxies at high redshift.  In this talk I will discuss  
recent observational results and theoretical implications   
from our surveys of star-forming galaxies at z=3.0+-0.25 and
z=1.0+-0.1.  Each survey contains roughly 800 galaxies with
spectroscopic redshifts and several thousand photometric candidates.   
I will conclude with a brief discussion of dust-obscured star-formation
at high redshift.  Numerous papers have used recent measurements
at 850 microns to argue that the vast majority of star-formation
at high redshift occurs in objects too heavily obscured by dust
to be included in optically selected surveys.  I will argue 
that this is not necessarily true---known optically selected
populations at 1<z<5 could by themselves have produced
the bulk of the 850um background.