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
Metastable rotational levels J NH 3 3 2 1 K 0 0 1 2 3
Lifetime of the Universe ?
Metastable rotational levels J NH 3 3 2 1 K 0 0 1 2 3
Breakdown of symmetry selection rules Geometry Permutation C 3 (123) ΔK = 0 ΔK = 3
Metastable rotational levels J NH 3 3 人 生 五 十 年 rs 2 1 0 a 50 ye 0 20 r ea y μ s Δk = 3 T. Oka, F. O. Shimizu, T. Shimizu, J. K. G. Watson, Ap. J 165, L 15 (1971) F. Y. Chu, T. Oka, J. Chem. Phys. 60, 4612 (1974) PH 3 As. H 3
H 3+ is simpler H 3 J + No inversion 3 2 1 0 Non-polar Δk = 3
The ideal energy levels of H 3 + H 3+ + H 2 → (H 5+)* → H 3+ + H 2 Δk = ± 3 forbidden transitions (J, K) J Ncrit ~ 200 cm-3 (3, 3) metastable level 361 K 27. 2 days (1, 0) (1, 1) ground level 32. 9 K K 0 ± 1 ± 2 ± 3 (2, 2) unstable level k Pan, Oka, Ap. J 305, 518 (1986)
Discovery of metastable interstellar H 3+ (3, 3) metastable (1, 1) ground level Subaru telescope Goto, Mc. Call, Geballe, Usuda, Kobayashi, Terada, Oka PASJ, 54, 951 (2002)
Sightline toward the Galactic center The Central Molecular Zone
Thermalization of H 3+ + H 2 → (H 5+)* → H 3+ + H 2 (J, K) J Ncrit ~ 200 cm-3 (3, 3) metastable level 361 K 27. 2 days (1, 0) (1, 1) ground level 32. 9 K K 0 ± 1 ± 2 ± 3 (2, 2) unstable level k
Elementary processes Radiation Collision Reaction Ψ’ A B C D ψ A B Rigorous Selection Rules ortho para ΔI = 0 Approximate Rules ortho para ΔI = 0 Trad 3 K « Tkin Random ΔItotal = 0
Cosmic ray ionization Steady State 10 -17 s-1 Rate Equations 0= Production Spontaneous emission 4 10 -7 s-1 Collision n(H 2) 100 cm-3 Destruction 10 -7 cm 3 s-1 Dissociative recombination 10 -7 s-1 10 -9 cm 3 s-1 Proton hop reaction Detailed balance H 3+ + H 2 (H 5+)* H 3+ + H 2 Oka, Epp Ap. J, 613, 349 (2004)
Discovery of hot and diffuse clouds Oka, Epp, Ap. J 613, 349 (2004) Oka, Geballe, Goto, Usuda, Mc. Call, Ap. J 632, 882 (2005)
Enter Gemini South Observatory (1, 1) ground level CMZ and spiral arms (3, 3) metastable level All CMZ High temperature (2, 2) unstable level Neither Low density CO Mostly spiral arms
The Expanding Molecular Ring Kaifu, Kato, Iguchi, Nature (1972) Scoville, Ap. J (1972) Whiteoak, Gardner, MNRAS (1979)
The central 30 pc of the CMZ The Quituplet Nagata et al. (1990) Okuda et al. (1990) Yusef-Zadeh, Morris, AJ (1987)
Other stars Oka, Geballe, Goto, Usuda, Mc. Call, Ap. J (2005)
Controversies T. Oka No hot gas in the Expanding Molecular Ring F. Le Petit J. Black Diffuse gas cannot be that hot Infrared pumping (2, 0) F. Yusef-Zadeh 4 categories of gases Ap. J 637, L 101 (2006) (3, 0) (1, 0) (3, 3)
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 CO, CS H 3+ Radio diffraction X-ray Cold Warm Hot Ultrahot 30 K 250 K 104 K 107 -8 K >104 cm-3 ~102 cm-3 ~0. 3 cm-3 0. 1 0. 01 0. 5 - 1 ~ 0. 5 Volume filling factor f « 1
Extragalactic H 3+ Z = 0. 05821 Geballe, Goto, Usuda, Oka, Mc. Call Ap. J in press
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
Surprise!! H 3+ more abundant in diffuse clouds!! Dense clouds Mc. Call, Geballe, Hinkle Oka, Ap. J 522, 338(1999) N(H 3+) ~ 3. 6 × 1012 cm-2 AV N(H 3+) ~ 4. 4 × 1013 cm-2 AV Diffuse clouds Per Mc. Call, Hinkle, Geballe, Moriarty-Schieven, Evans, Kawaguchi, Takano, Smith, Oka, Ap. J 567, 391 (2002)
Central Molecular Zone, the treasure house of H 3+ M ~ 5 × 107 M⊙ Dominantly molecular Dense clouds, n(H 2) > 104 cm-4 Volume filling factor 0. 1 Hot gas T ~ 300 K High velocity dispersion Low dust temperature T ~ 20 -30 K Morris, Serabyn, ARA&A (1996) CMZ Mezger, Duschl, Zylka, A&A Rev. (1996)
Sightlines toward the CMZ
Extraordinary radio emission • Radio Arc – Arched filaments – Nonthermal filaments • Sgr A* Yusef-Zadeh, Morris, AJ (1987)
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