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Lyman Limit Systems

Lyman Limit Systems. Chris Cleveland, Ryan Choung, and Renyue Cen. What are Lyman Limit Systems? . Clumps of neutral hydrogen that absorb high energy photons (above 13.6 eV). Have Column Densities ranging from 1.6x10 17 cm -2 to 1.0x10 20 cm -2. Why Lyman Limit Systems?.

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Lyman Limit Systems

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  1. Lyman Limit Systems Chris Cleveland, Ryan Choung, and Renyue Cen

  2. What are Lyman Limit Systems? • Clumps of neutral hydrogen that absorb high energy photons (above 13.6 eV). • Have Column Densities ranging from 1.6x1017 cm-2 to 1.0x1020 cm-2

  3. Why Lyman Limit Systems? • The mean free path of ionizing photons is directly determined by the abundance of LLS • Have an uncertain role in galaxy formation • Prior computational studies have underestimated the observed abundance of LLS (Storrie-Lombardi et al. (1994) and Gardner, Katz et al. (1997))

  4. Big Picture Cosmological Simulation • Based on WMAP5 cosmological parameters • Hydro simulation using enzo and AMR code, including star formation and supernova feedback • Cubic box (64 h-1 Mpc)3, with unprecedented resolution of 350 pc • Simulation runs from z = 100.

  5. What are we doing? • We are focusing in on a particular region in the simulation at a particular snapshot • Size: (~1.6 h-1 Mpc)3 • Resolution: 1 h-1 Kpc • Time: z = 3

  6. Column Densities x

  7. Histogram of Column Densities

  8. Column Density v Neutral Fraction

  9. Column Density v Mass of Neighbor Galaxy

  10. Distance to Neighbor Galaxy v Mass of Neighbor Galaxy

  11. Complications • Ambiguity of neighbor galaxies • Galactic tides • Arbitrary criteria for segment cut off • Arbitrary criteria for minimum mass of galaxy

  12. What’s next? • Increase simulation size and resolution: In the future, we plan to expand size to (~6 h-1 Mpc)3 and increase resolution to .25 h-1 kpc • Improving criteria for neighbor galaxy (ie. include galactic mass as a factor) • Establish where lyman limit systems typically lie with respect to their neighbor galaxies (ie. whether they are within virial radius) • Study different redshifts

  13. In the end… • Compare our high resolution results with observational data. • Compare column density distributions. • Compare mean absorption profiles

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