H 3 + , the new probe for ionization rate 

1. 7 H3+, the new probe for ionization rate the cosmic ray Takeshi Oka Department of Astronomy and Astrophysics and Department of Chemistry The Enrico Fermi Institute, University of Chicago Tom Geballe Gemini Observatory Nick Indriolo,Ben McCall University of Illinois, Urbana-Champaign Cosmic Ray Interactions: Bridging High and Low Energy Astrophysics Leiden, March 14, 2011

2. 6 Astronomers’ Periodic Table H He Ne O C N Si S Ar Mg Fe Ben McCall

3. 5 Hydrogenic Probes H+ H2+ H3+ ~ 10-7 10-8 H H2 H H3+ H H2 + Ewen & Purcell 1951 Muller & Oort 1951 Carruthers 1970 Spitzer et al. 1973 Geballe & Oka 1996

4. 4 H3+the most direct probe for soft cosmic ray

5. H3+the most direct probe for soft cosmic ray Simple chemistry: production 3 H+ H2+ H3+ OH, HD H H2 H2→H2+ + e H2++ H2 → H + H3+ 1.7 eV = 10-18 ~ 10-14 s-1 R = kLn(H2) P. Langevin 1905 r-4 10-9 cm3 s-1 104 - 102 cm-3 dn(H3+)/dt = dn(H2+)/dt = n(H2)

6. 2 H3+the most direct probe for soft cosmic ray Simple chemistry: destruction Dense Clouds(~104 cm-3) C  CO H3+ + CO → H2 + HCO+ dn(H3+)/dt = kLn(H3+)n(CO) 10-9 cm3 s-1 r-4 Diffuse Clouds(~102 cm-3) C  C+ + e 10-7 cm3 s-1 r-1 H3+ + e → 3H, H2 + H  dn(H3+)/dt = ken(H3+)n(e) = n(H2) Steady state n(H3+) = n(H3+) = N(H3+)/L (nH/nC)f(H2)/2 = f(H2) = 2n(H2)/nH

7. 1 H3+the most direct probe for soft cosmic ray  L  N(H3+) Dense clouds L = 2 kLN(H3+) (nC/nH)1.5 L = (0.6 – 2.3)  102 cm s-1 = 3  10-17s-1L = (0.6 – 2.3) pc N(H3+)obs = (1.1 – 5.2)  1014 cm-2 McCall, Geballe, Hinkle, Oka, 1999, ApJ, 522, 338 Diffuse clouds L = 2 keN(H3+) (nC/nH)/ f(H2) L = (0.4 – 4.4)  104 cm s-1 N(H3+)obs = (0.21 – 2.4)  1014 cm-2 = 4.5  10-16 s-1L = (3 – 29) pc Indriolo, Geballe, Oka, McCall, 2007, ApJ, 671,1736 Galactic center L = 2 keN(H3+) (nC/nH)SV RC/H / f(H2) L > (1.2 – 4.2)  105 cm s-1 = 1.5  10-15 s-1L > (24 – 84) pc N(H3+)obs = (1.8 – 6.1)  1015 cm-2 RC/H 3– 6.7 Goto, Usuda, Nagata, Geballe, McCall, Indriolo, Suto, Henning, Morong, Oka, 2008, ApJ, 688, 306 Rolleston et al. 2000, A&A, 363, 557 Esteban et al. 2005, ApJ, 618, L95 RX 3– 10, > 3 Sodroski, et al. 1995, ApJ 452, 262 Arima, Sofue, Tsujimoto, 1996, PASJ 48, 275

8. Telescopes and spectrometers Telescope D Spectrom. λ/Δλ UKIRT 3.8 m CGS4 40,000 Mauna Kea 1982 Subaru8.2 m IRCS 20,000Mauna Kea 2000 Gemini South 8 m Phoenix 60,000Cerro Pachon 2003 VLT 8.2 m CRIRES 100,000 Cerro Paranal 2006 Gemini North 8 m GENIRS 18,000 Mauna Kea 2011 Gemini North Gemini South Subaru UKIRT VLT

9. 0 Remarkable similarity between velocity profiles of H3+ toward Iota and H2O+, CH+ toward Sgr B2 Herschel observations of ortho- and para-oxidaniumyl (H2O+) in spiral arm clouds toward Sgr B2(M) ⋆ P. Schilke,1,2 C. Comito,2 H. S. P. M¨uller,1 E. A. Bergin,3 E. Herbst,14 D. C. Lis,4 D. A. Neufeld,20 T. G. Phillips,4 T. A. Bell,4 G.A. Blake5 E. Caux,6,7 C. Ceccarelli,8 J. Cernicharo,9 N. R. Crockett,3 F. Daniel,9,10 M.-L. Dubernet,11,12 M. Emprechtinger,4 P. Encrenaz,10 M. Gerin,10 T. F. Giesen,1 J. R. Goicoechea,9 P. F. Goldsmith,13 H. Gupta,13 C. Joblin,6,7 D. Johnstone,15 W. D. Langer13 W. B. Latter16 S. D. Lord,16 S. Maret,8 P. G. Martin,17 G. J. Melnick,18 K. M. Menten,2 P. Morris,16 J. A. Murphy,19 V. Ossenkopf,12,21 J. C. Pearson,13 M. P´erault,10 R. Plume,22 S.-L. Qin,13 S. Schlemmer,1 J. Stutzki,1 N. Trappe,19 F. F. S. van der Tak,21 C. Vastel,6,7 S. Wang,3 H. W. Yorke,13 S. Yu,13 N. Erickson,25 F.W. Maiwald,13 J. Kooi,4 A. Karpov,4 J. Zmuidzinas,4 A. Boogert,4 R. Schieder,1 and P. Zaal21 3 kpc Scutum Sgittarius H2O+ 110← 101 H3+ R(1,1)l H2O+ 111← 000 A&A June 22 2010 E. Falgarone et al. 2010 Geballe & Oka, 2010, ApJ, 709, L70 17 pc