1. Revelation of a vast amount of warm and diffuse gas and high ionization rate in the Central Molecular Zone of the Galactic center 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 Informal talk at Onsala Observatory: March 24, 2011 March 19, 1981 Tom Geballe Gemini Observatory Miwa Goto Max-Planck Institut für Astronomie Ben McCall University of Illinois at U-C

2. C 60 H3+H3+ H–C≡C–C≡C–C≡C–C≡C–C≡N H–C≡C–C≡C–C≡C–C≡N H–C≡C–C≡C–C≡N 1975 X-ogen 1970 Harry Kroto Buhl, Snyder, Klemperer 1973 Watson Herbst and Klemperer Black and Dalgarno

3. 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

4. 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

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

7. (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 Oka and Epp, 2004, ApJ, 613, 349 (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

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

9. Simple chemistry of H 3 + : N(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(H 2 ) 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)

10. 1° × 1° 140 pc × 140 pc Super-massive clusters

11. 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 smoothness location - 1.2º < ℓ - ℓº < 1.2º- 0.1º < b - bº < 0.1 º

12. The CO test Most old (late-type) cool stars are useless Bright dust-embedded stars with smooth spectrum are scarce

13. New bright dust-embedded stars suitable for H 3 + spectroscopy

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

15. 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

16. 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% ?

17. 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