Title:

The MOSAIC Survey: Multiwavelength Observations of Structure Around 
Intermediate-z Clusters



Roy Gal
University of Virginia



Abstract:

Superclusters represent the largest scale at which gravitational
structure formation is important at the current epoch. Thus, the
history of supercluster formation provides important constraints on
theories of structure formation via gravitational collapse and the
evolution of a substantial fraction of the baryons in the universe.
Although such structures have been studied in the local universe, they
remain largely unexplored at higher redshifts, where most observations
have targeted only the densest cluster cores. By expanding
observations to intermediate-density regimes at redshifts around one,
we examine regions of intense galaxy transformation, including groups
and filaments. To increase the sample of high-redshift superclusters,
we have undertaken MOSAIC, a multi-band survey of regions around a
sample of well-studied, rich clusters at $z > 0.5$. This
survey consists of (1) deep optical photometry to identify potential
structures; (2) extensive high-resolution spectroscopy to confirm
structure members and study their stellar populations; (3)
near-infrared imaging to obtain stellar masses and SEDs; (4) mid- and
far-infrared imaging to study AGN, starbursts, and dust; (5) X-ray
observations of the intracluster gas and AGN, and (6) radio
observations to detect obscured star formation and AGN. We present
some of the early results of this survey, including multiple new
supercluster systems and properties of their galaxy populations. The
importance of multi-wavelength observations to understand
environmental effects on galaxy properties. star formation, and AGN is
discussed.