1. Revelation of a vast amount of warm (~ 250 K) and diffuse (≤ 100 cm -3 ) gas and high ionization rate (ζ > 10 -15 s -1 ) in the Central Molecular Zone by the Infrared Spectrum of H 3 + Takeshi Oka Department of Astronomy and Astrophysics and Department of Chemistry The Enrico Fermi Institute, University of Chicago Star formation under extreme conditions: the Galactic center at the Besançon Observatory, December 7, 2010 Tom Geballe Gemini Observatory Miwa Goto Max-Planck Institut für Astronomie

2. 2005 Revelation of warm and diffuse gass near GC Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 1999 High H 3 + abundance in the Galactic center H 3 +, the new astrophysical probe + 1951 1970 1973 1996 1980 Oka, Phys. Rev. Lett. 45, 531 Laboratory Spectrum 1996 Geballe, Oka, Nature 384, 334 Interstellar H 3 +, Discovery, Dense Clouds H H2H2 H3+H3+ 1989 - 95 2002 Metastable H 3 +, Discovery, Galactic center Goto, McCall, Geballe, Oka, et al. PASJ 54, 951 1975 HC 5 N, HC 7 N, HC 9 N 2008 Ubiquity Central 30 pc of the Galactic center Goto, Geballe, Oka, et al. ApJ 688, 306 T.G. 2010 Exploring wider regions of the Galactic center Geballe, Oka, ApJ, 709, L70

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

4. Quintuplet Cluster 1° × 1° 140 pc × 140 pc Super-massive clusters GCS 3-2

5. High abundance of H 3 + in the CMZ CMZ R(1, 1) u R(1, 0) T. R. Geballe, Phil. Trans. Roy. Soc. Lond. A358, 2503 (2000) 3 × 10 14 cm -2 10 -5 10% 400 pc

6. (J, K) = (3, 3) metastable H 3 +, the fingerprint of GC Metastable 27.2 days 20.4 days Ortho I = 3/2 Para I = 1/2 J K 16 hrs 8 hrs (3,3) (2,2) (1,1) Pan and Oka, 1987, ApJ, 305, 518 (1,0) Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka, 2002, PASJ 54, 951 361 K CO J = 1 (2,2) unstable (3,3) metastable (1,1) ground T ~ 250 K n ≤ 100 cm -3 Oka, Geballe, Goto, Usuda, McCall, 2005, ApJ, 632, 882 Spontaneous breakdown of symmetry

7. Ubiquity of H 3 + Sgr A* to 30 pc East 30 pc

8. 1° × 1° 140 pc × 140 pc Super-massive clusters

9. Search for bright and hot stars in the CMZ GLIMPSE Point Source Catalogue of the Spitzer Space Telescope, L to M Ramírez et al. 2008, ApJS, 175, 147 2MASS photometry at J, H, and K band ̲ s Skrutskie et al. 2006, AJ, 131, 1163 ~ 2,000,000 stars L < 7.5 ~ 3,000 stars (J – K)/(K – L) < 2.5K - L > 1.5J - K > 5 ~ 300 stars Low res. CO first overtone, 2.2 – 2.4μm Candidate stars Selected stars High res. H 3 + and CO spectroscopy brightness youth hotness location - 1.2º < ℓ - ℓº < 1.2º- 0.1º < b - bº < 1.0 º

10. The CO test Old (late-type) cool stars are useless Bright, young, hot stars are scarce

11. New bright and hot dust embedded stars suitable for H 3 + spectroscopy Geballe and Oka, ApJ, 709, L70-73 (2010)

12. Two sightlines with remarkable H 3 + spectrum α ι Geballe and Oka, ApJ, 709, L70-73 (2010) 0 – 30 pc EastQuintuplet, α, ι

13. Simple chemistry of H 3 + →  ·L Destruction H 3 + + e → H + H + H Production H 2 → H 2 + + e H 2 + + H 2 →H + H 3 +   L = 2 k e N(H 3 + ) (n C /n H ) SV R X / f 7.3 ×10 -8 cm 3 /s1.6 ×10 -4 1 (1.8-6.1) ×10 15 cm -2 3 (  L) min = (1.3 – 4.3) ×10 5 cm/s  L 10 -16 s -1 (0.4 – 1.4) kpc 10 -15 s -1 40 - 140 pc Goto, Usuda, Nagata, Geballe, Indriolo, McCall, Suto, Henning, Morong, and Oka, ApJ, 668, 306 (2008) dn(H 3 + )/dt =  n(H 2 ) = k e n(H 3 + )n(e)

14. Lazio & Cordes, ApJ, 505, 715 (1998) 80% 10 7-8 K 10% 10 4-6 K n e 10 cm -3 10% 50 K 10 4 cm -3 New category of gas in the CMZ f: Previous concept drastically changed T ~ 250 K n ~ 100 cm -3 L ~ 60 pc f ~30%  ~ 1.5 × 10 15 s -1 Schultheis et al. ApJ 495, 157 (2009) 2%

15. Chandra 20 pc × 20 pc (0.5 – 8) keV Muno et al. ApJ 589, 225 (2003) Warwick, Sakano Decourchelle (2006) Revnivtsev et al. (2006) X-ray: Chandra comes to rescue

16. Remarkable similarity between velocity profiles of H 3 + toward Iota and H 2 O +, CH + toward Sgr B2 Herschel observations of ortho- and para- oxidaniumyl (H 2 O + ) in spiral arm clouds toward Sgr B 2 (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 A&A June 22 2010 Geballe & Oka, 2010, ApJ, 709, L70 H 3 + R(1,1) l H 2 O + 1 11 ← 0 00 H 2 O + 1 10 ← 1 01 17 pc 3 kpcScutum Sgittarius E. Falgarone et al. 2010

17. NH 3 Metastable rotational levels 0123 0 1 2 3 J K NH 3 ΔK = 0

18. 0123 0 1 2 3 J K NH 3 NH 3 Metastable rotational levels Δk = 3

19. Metastable rotational levels 0 1 2 3 J NH 3 μ T. Oka, F. O. Shimizu, T. Shimizu, J. K. G. Watson, ApJ 165, L15 (1971) 50 years Δk = 3 200 years

20. H 3 + is simpler 0 1 2 3 J Δk = 3 H3+H3+ Non-polar No inversion