1. Observations of OH + and H 2 O + Across the Galaxy with Herschel Nick Indriolo 1, David Neufeld 1, Maryvonne Gerin 2, & PRISMAS consortium 1 – Johns Hopkins University 2 – LERMA, CNRS, Observatoire de Paris & ENS June 20, 2012 67th International Symposium on Molecular Spectroscopy WH05

2. What is PRISMAS? PRobing InterStellar Molecules with Absorption line Studies Herschel guaranteed time key program headed by Maryvonne Gerin Uses H II regions as background THz sources to probe intervening clouds for rotational transitions of small moleclues

3. PRISMAS sight lines

4. Oxygen Chemistry CR + H  H + + e - + CR' H + + O  O + + H O + + H 2  OH + + H OH + + H 2  H 2 O + + H H 2 O + + H 2  H 3 O + + H OH + + e -  products H 2 O + + e -  products H 3 O + + e -  products O + + H  H + + O H + + e -  H + hν OH + H2H2 H2O+H2O+ H2H2 H3O+H3O+ CR H H+H+ O O+O+ H2H2 H e-e- e-e- e-e- e-e-

5. H 2 Fraction & Ionization Rate OH + + H 2 H 2 O + + H 2 H 2 O + + e - CR + H OH + + H 2 OH + + e -

6. OH + Transitions N=0 N=1 J=1 J=2 J=0 F=3/2 F=1/2 F=3/2 F=1/2 F=3/2 F=5/2 909 GHz971 GHz 1033 GHz

7. OH + Observations

8. H 2 O + Transitions Schilke et al. 2010 A&A, 521, L11Bruderer et al 2010 A&A, 521, L44

9. ortho-H 2 O + Observations

10. para-H 2 O + toward W51

11. W49N Profile Fitting Neufeld et al. 2010 A&A, 521, L10

12. Determining Column Densities

13. W49N Results v LSR ΔvΔvN(OH + )N(H 2 O + ) (km/s) (10 13 cm -2 ) 6.65.12.90.42 13.44.62.20.69 21.27.08.20.56 34.79.026.12.68 43.58.47.50.72 62.513.318.91.67 f H2 0.049 0.126 0.021 0.033 0.031 0.028 N(H) (10 21 cm -2 )... 6.95 7.23 εζ H (10 -17 s -1 )... 4.28 2.19 Neufeld et al. 2010 A&A, 521, L10 Assume ε=0.1

14. Preliminary Ionization Rates ΔvΔvζHζH σ(ζ H ) (km/s)(10 -16 s -1 ) 30—504.282.14 50—802.191.10 -2.5—73.361.68 7—201.640.82 20—340.190.10 0—112.101.05 11—171.480.74 42—551.310.66 55—750.470.24 W49N G34.3+0.1 W51

15. Distribution of Ionization Rates Probability Density Function Cumulative Distribution Function Indriolo & McCall 2012 ApJ, 745, 91

16. Future Work Continue analyzing OH +, o-H 2 O +, p-H 2 O +, and H 3 O + spectra from PRISMAS Add OH + and o-H 2 O + observations from the WISH program to our sample Utilize new JVLA observations of H I in inferring ionization rates Map ζ H as a function of position in the Galaxy