Collaborative Research: Chemistry and Structure Formation at High Redshift

Harvard University, Cambridge MA

Investigators

Abstract

AST-0088213 Alexander Dalgarno This is a collaborative research project with Drs Phillip Stancil, (the University of Georga, AST0087172), and Stephen Lepp, (University of Nevada, Las Vegas, AST0087348). This program will construct models to investigate the formation of the first cosmological objects. These models will describe the history of the first bound objects to form from the primordial gas in the early universe. They will include the coupled evolution of the time-dependent, nonequilibrium chemical, atomic and molecular level populations as well as the nonequilibrium rovibrational level populations of the molecules with contributions due to chemical reactions in the primordial gas. The models can be used to suggest strategies for observing structures in the early universe in the Infrared from space. This program will use astrophysical modeling to investigate the formation of the first cosmological objects. These models will compute the coupled evolution of the time-dependent nonequilibrium chemical, atomic and molecular level population, thermal, and hydrodynamic history of the first bound objects to form from the primordial gas. This will be the first time such extensive, coupled evolution models have been attempted. In addition, this project will investigate the explicit nonequilibrium rovibrational level populations of the primordial molecules with contributions due to chemical reactions, resulting in an improved determination of molecular cooling and the prediction of the emission spectra of primordial clouds. The emission spectra will be used to suggest the most likely ways these objects may be observed with the next generation of infrared space telescopes. The needed atomic and molecular data and derived cooling functions will be assembled and posted on the World Wide Web. The data that is not available, primarily involving rovibrational state-specific molecular collisions, will be computed with established quantum-mechanical techniques. The studies of the primordial gas will be extended to follow protogalaxy and protostar formation under increasing metallicity and radiation field conditions to the beginning of the era of Population II. These studies will be relevant to the interpretation and planning of future space-based observations with NGST, SIRTF, FIRST, and Astro-F and ground-based telescopes. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC). ***