Nanase Harada: Molecules in CND (Theory)

Line survey in the southwest lobe of the CND
  • IRAM + APEX
  • RADEX LVG analysis
  • Assumed source size
    • density 10^5
    • grav unstable
  • column densities in many molecules
Physics affecting the chemistry
  • cosmic ray ionization rate
  • X-ray ionization + Less penetrating
  • UV photons + highly dependent on extinction + 10^4-10^5 G_0
  • Shocks + shock chemical models + gas & dust phase shock chem
Concl
  • High CR rates favored (zeta = 10^-14/s) + lower acceptable if UV included (zeta = 10^-15/s)

Questions

  • Q: Ionization provides external pressure on clumps.
  • A: Would like to include in model...?
  • Q: Gamma ray ionization could do something. Considered?
  • A: No, but cross-section is low. Need lots of gamma rays.
  • Q Farhad: Age of molecular ring based on chemical model?
  • A: Assumed some age from CR turn-on, not age of CND
  • Q: More extreme CR ionization rate near Arches cluster, etc. What is the best chemical approach for higher CR rate?
  • A: If CR rate too high, can't form molecules / will destroy molecules

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