Science Reference Mission

This is a large and critical issue that will see its first steps
at definition during this SWG meeting.  One topic has been mentioned,
that of a cosmic shear survey.  This is an important scientific topic
and one that can utilize a combination of many databases.  I would like
to suggest a second possible topic for your consideration, and that
is galaxy evolution as a function of cosmic epoch, from z = 10 to 
z = 0.1.  A buzzword title might be: The History of the Visible
Universe.  There are numerous critical and unsolved astrophysical problems 
associated with this topic, as you well know.  Why are old galaxies so
red?  How was the IGM originally seeded with metals?   Did primordial
black holes form before the first galaxies?  What caused the first epoch of
starbursts?  Are mergers really the answer to all problems?  Were the
seeds of galaxy clusters present at z = 20, and if so what has retarded
their formation so some are still forming now?  Can you build big
galaxies from dwarfs?  (Recent evidence says no for the Local Group.)

One of the virtues of this topic is that it spans all of the major
subject areas of the SWG; stars and stellar pops, galaxy formation and
evolution, and cosmology.  A second virtue is that it will need large
amounts of survey data from multiple wavelengths: radio to x-ray, and
it will require large numbers of spectra that are now becoming available
from spectroscopic surveys, as well as color information and photometric
redshift data becoming available through current surveys.  A third
virtue is that this topic lends itself well to comparison/confrontation
with many theoretical simulations that either have been done or are in
the process of being done.  These include not only the large scale
structure and cosmology simulations but also simulations of the
evolution of galaxy clusters and the simulations of galaxy evolution
as a result of galaxy mergers and near encounters.  A final virtue is
that this project is large enough that it can, and must, involve all of the 
resources of the full EURO-VO.  It can also be broken down into several
smaller subtopics that are more or less self contained and address
specific astrophysical problems that need to be solved in order to
see the entire puzzle made clear.

This is just a skeletal overview.  If there is any interest in pursuing
this topic, please let me know.  I will be glad to contribute what I can
from afar.

With best wishes,

Dave De Young