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Cloudy: Numerical Simulations of Plasmas and their Spectra. If a picture is worth a thousand words, a spectrum is worth a thousand pictures. Understanding Starburst Galaxies - Numerical Simulations of Diffuse Interstellar Gas Gary Ferland, Nick Abel, Ryan Porter, Gargi Shaw UK Physics.
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Cloudy:Numerical Simulations of Plasmasand their Spectra If a picture is worth a thousand words, a spectrum is worth a thousand pictures Understanding Starburst Galaxies - Numerical Simulations of Diffuse Interstellar Gas Gary Ferland, Nick Abel, Ryan Porter, Gargi Shaw UK Physics
Cloudy:Numerical Simulations of Plasmasand their Spectra If a picture is worth a thousand words, a spectrum is worth a thousand pictures
quasars Local structure Primordial nucleosynthesis Cosmic background radiation
Cloudy:Numerical Simulations of Plasmasand their Spectra If a picture is worth a thousand words, a spectrum is worth a thousand pictures
A non-equilibrium gas • Gas emitting spectrum has a very low density • It is exposed to a range of radiation fields and particles • Populations of levels, ionization, spectrum, determined by many micro-physical processes • Not characterized by a single temperature • Or, every level has a different temperature
Photoionization Equilibrium • energetic radiation interacts with surrounding gas • photoionization • photoelectrons heat electron bath • electrons excite heavy elements • collisionally excited line cooling • free electrons recombine • recombination lines
The He-like iso-electronic sequence • He is second most abundant element, produced in Big Bang • A two-electron system, its quantum mechanics is not trivial Emission from a pure-helium plasma • Ryan Porter, PhD, in collaboration with Keith MacAdam & Rob Bauman
Molecular hydrogen • Most baryons are in H2 • Rotation-vibration emission in IR, electronic absorption in UV • Gargi Shaw, PhD • Energy levels, transition probabilities, well understood • Collisional rates poorly known – being done with ORNL
Heavy-element chemistry • Chemistry in a hard vacuum, at cryogenic temperatures • Series of ion-molecule reactions involving cosmic rays, H2, and small solids (grains) • Nick Abel, PhD
Cloudy:Numerical Simulations of Plasmasand their Spectra If a picture is worth a thousand words, a spectrum is worth a thousand pictures