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AST 381S




Self-Consistent Cosmological Initial Conditions for the First Objects in the Early Universe

Formation of the first objects in the early universe such as the Pop III stars is a semi-cosmological problem due to the nature of the primordial gas. A typical, reliable treatment of this problem is a N-body/hydrodynamics simulation with cosmological initial conditions for the dark matter component (dissipationless) and the baryon component (dissipationless). A reliable linear perturbation analysis is prerequisite for constructing the initial conditions in the early Universe.

There have been new developments in the linear perturbation analysis recently, both in the large- scale regime and small-scale regime. I will review a recent development of the linear perturbation analysis in the small-scale regime, and our own attempt to create the most self-consistent cosmological initial conditions which would be suitable for the study of the formation of the first objects in the early Universe.


Turmoil in Orion: The Nearest Massive Protostar

Massive star formation is a complicated process, so theories describing it need to be tested closely against observations. The Orion KL nebula, inside the Orion Nebular Cluster, is the nearest and best-studied region that is thought to harbor a massive protostar. Unfortunately, it exhibits great complexity and there is good evidence that the gas has been influenced by some unusual dynamical events in the last 1000 years. I review the observations of this region and describe how a theoretical model of massive star formation from turbulent massive gas cores is still very relevant to understanding what is happening in Orion KL.


The Extraction of Baryonic Acoustic Oscillations using the FITEX Method

The first step toward a determination of the equation of the state of dark energy from HETDEX is an extraction of the baryonic acoustic oscillations (BAO) in the matter power spectrum from the observed galaxy power spectrum. A FIT-and-EXtraction (FITEX) method is an efficient way for doing this. Following an initial development of this method for the 1-dimensional power spectrum, I extend it to include the 2-dimensional information in redshift space, which will be useful for correcting non-linear redshift space distortion effects and estimating a value of the Hubble parameter from HETDEX.



16 April 2007
Astronomy Program · The University of Texas at Austin · Austin, Texas 78712
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