2. The (3, 3) metastable rotational level of H 3 + Takeshi Oka Department of Chemistry and Department of Astronomy and Astrophysics The Enrico Fermi Institute, The University of Chicago New Horizon of Astrochemistry and Laboratory Spectroscopy March 16, 9 am, 2006 I am looking for a postdoc, Laboratory or Observatory

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

4. Lifetime of the Universe ?

5. Metastable rotational levels 0123 0 1 2 3 J K NH 3

6. Breakdown of symmetry ΔK = 0 ΔK = 3 Geometry C 3 Permutation (123) selection rules

7. 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 人生五十年人生五十年 Δk = 3 200 years F. Y. Chu, T. Oka, J. Chem. Phys. 60, 4612 (1974) PH 3 AsH 3

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

9. J K 32.9 K 361 K (J, K) The ideal energy levels of H 3 + (3, 3) metastable level (1, 1) ground level Δk = ± 3 forbidden transitions 27.2 days (2, 2) unstable level (1, 0) 0 ±1 ±2 ±3 k N crit ~ 200 cm -3 H 3 + + H 2 → (H 5 + )* → H 3 + + H 2 Pan, Oka, ApJ 305, 518 (1986)

10. Discovery of metastable interstellar H 3 + Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka PASJ, 54, 951 (2002) (3, 3) metastable Subaru telescope (1, 1) ground level

11. Sightline toward the Galactic center The Central Molecular Zone

12. J K 32.9 K 361 K (J, K) Thermalization of H 3 + (3, 3) metastable level (1, 1) ground level 27.2 days (2, 2) unstable level (1, 0) 0 ±1 ±2 ±3 k N crit ~ 200 cm -3 H 3 + + H 2 → (H 5 + )* → H 3 + + H 2

13. Radiation Collision Reaction Rigorous Selection Rules Approximate Rules Random ortho  para ΔI = 0 ortho  para ΔI = 0 ΔI total = 0 AAAA BBBB CACA DBDB Ψ’ψΨ’ψ T rad  3 K « T kin Elementary processes

14. Rate Equations Production Spontaneous emission 4  10 -7 s -1 Collision n(H 2 ) 100 cm -3 10 -7 s -1 Destruction 10 -9 s -1 10 -17 s -1 10 -7 cm 3 s -1 10 -9 cm 3 s -1 H 3 + + H 2  (H 5 + )*  H 3 + + H 2 Detailed balance Cosmic ray ionization Dissociative recombination Proton hop reaction 0 = Steady State Oka, Epp ApJ, 613, 349 (2004)

15. Discovery of hot and diffuse clouds Oka, Epp, ApJ 613,349 (2004) Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

16. (1, 1) ground level CMZ and spiral arms (3, 3) metastable level All CMZ (2, 2) unstable level Neither CO Mostly spiral arms High temperature Low density Enter Gemini South Observatory

17. The Expanding Molecular Ring Kaifu, Kato, Iguchi, Nature (1972) Scoville, ApJ (1972) Whiteoak, Gardner, MNRAS (1979)

19. The central 30 pc of the CMZ Yusef-Zadeh, Morris, AJ (1987) Nagata et al. (1990) Okuda et al. (1990) The Quituplet

20. Oka, Geballe, Goto, Usuda, McCall, ApJ (2005) Other stars

21. Controversies T. Oka No hot gas in the Expanding Molecular Ring F. Le PetitDiffuse gas cannot be that hot J. BlackInfrared pumping (1, 0) (3, 0) (2, 0) (3, 3) F. Yusef-Zadeh 4 categories of gases ApJ 637, L101 (2006)

22. The Galactic center The Central Molecular Zone (CMZ) The treasure house of H 3 + Discovery of metastable H 3 + Revelation of warm and diffuse gas Cold 30 K >10 4 cm -3 Hot 10 4 K ~10 2 cm -3 Ultrahot 10 7-8 K ~0.3 cm -3 Warm 250 K ~10 2 cm -3 CO, CSX-ray H3+H3+ Radio diffraction Volume filling factor f 0.10.5 - 1 ~ 0.5 «1 0.01

23. Extragalactic H 3 + Geballe, Goto, Usuda, Oka, McCall ApJ in press Z = 0.05821

25. The (3, 3) metastable rotational level of H 3 + Takeshi Oka Department of Chemistry and Department of Astronomy and Astrophysics The Enrico Fermi Institute, The University of Chicago New Horizon of Astrochemistry and Laboratory Spectroscopy March 16, 9 am, 2006 I am looking for a postdoc, Laboratory or Observatory

26. Dense clouds McCall, Geballe, Hinkle Oka, ApJ 522,338(1999) Diffuse clouds McCall, Hinkle, Geballe, Moriarty-Schieven, Evans, Kawaguchi, Takano, Smith, Oka, ApJ 567, 391 (2002)  Per Surprise!! H 3 + more abundant in diffuse clouds!! N(H 3 + ) ~ 3.6 ×10 12 cm -2 A V N(H 3 + ) ~ 4.4 ×10 13 cm -2 A V

27. Central Molecular Zone, the treasure house of H 3 + M ~ 5 × 10 7 M ⊙ Dominantly molecular Dense clouds, n(H 2 ) > 10 4 cm -4 Volume filling factor 0.1 Hot gas T ~ 300 K High velocity dispersion Low dust temperature T ~ 20-30 K Mezger, Duschl, Zylka, A&A Rev. (1996) Morris, Serabyn, ARA&A (1996) CMZ

29. Sightlines toward the CMZ

30. Extraordinary radio emission Radio Arc –Arched filaments –Nonthermal filaments Sgr A * Yusef-Zadeh, Morris, AJ (1987)