NSF Org:	AST Division Of Astronomical Sciences
Recipient:	THE TRUSTEES OF PRINCETON UNIVERSITY
Initial Amendment Date:	September 12, 2002
Latest Amendment Date:	June 3, 2004
Award Number:	0206299
Award Instrument:	Continuing Grant
Program Manager:	Nigel Sharp nsharp@nsf.gov  (703)292-4905 AST  Division Of Astronomical Sciences MPS  Directorate for Mathematical and Physical Sciences
Start Date:	September 15, 2002
End Date:	August 31, 2006 (Estimated)
Total Intended Award Amount:	$368,793.00
Total Awarded Amount to Date:	$368,793.00
Funds Obligated to Date:	FY 2002 = $122,931.00 FY 2003 = $122,931.00 FY 2004 = $122,931.00
History of Investigator:	Renyue Cen (Principal Investigator) Jeremiah Ostriker (Co-Principal Investigator)
Recipient Sponsored Research Office:	Princeton University 1 NASSAU HALL PRINCETON NJ  US  08544-2001 (609)258-3090
Sponsor Congressional District:	12
Primary Place of Performance:	Princeton University 1 NASSAU HALL PRINCETON NJ  US  08544-2001
Primary Place of Performance Congressional District:	12
Unique Entity Identifier (UEI):	NJ1YPQXQG7U5
Parent UEI:
NSF Program(s):	EXTRAGALACTIC ASTRON & COSMOLO
Primary Program Source:	app-0102  app-0103  app-0104
Program Reference Code(s):	0000, 1206, OTHR
Program Element Code(s):	121700
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.049

ABSTRACT

AST 0206299
Cen

The formation and evolution of cosmic structures, including galaxies, clusters of galaxies and large-scale structure, are fundamental problems of modern cosmology. While the Big Bang picture of how the Universe began is generally accepted, the details of how and when structures developed and formed are in hot debate. On scales larger than clusters of galaxies (>10 million light years across) it is generally believed that gravity is the dominant force and structures grow from small initial seeds planted in the very early universe (<< 1 second since the Big Bang), because gravity is attractive and unstable. However, on smaller scales gas hydrodynamics, microphysics (i.e., forces on atomic scales) and star formation processes play progressively more important roles in shaping and determining when galaxies form and how they evolve; the picture at these smaller scales is much less clear. The radiation field, especially, the ultra-violet radiation that is capable of ionizing atomic hydrogen must play a very important role in these processes. In particular, it determines when atomic hydrogen is fully ionized and the universe is cleared of hydrogen "fog" and becomes transparent to distant sources. This epoch has been characterized as the "end of the dark ages". Since radiation controls the evolution of the thermodynamic state of the gas, a fraction of which is subsequently incorporated into stars, it is essential to include radiation hydrodynamics in full detail in cosmological computer simulations in order to provide answers to many of the important questions in modern cosmology. This is a formidable task to tackle even with the fastest supercomputers today. Dr. Cen and his collaborators have developed an efficient way to compute this complicated situation and begun to carry out a program that should help provide some clues about how the radiation field and the matter evolve with time.
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