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Spectroscopy of H 3 + and CO toward the Galactic center

Spectroscopy of H 3 + and CO toward the Galactic center. Takeshi Oka , Christopher P. Morong, Department of Astronomy And Astrophysics and Department of Chemistry University of Chicago Thomas R. Geballe, Gemini Observatory, Hilo, Hawaii

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Spectroscopy of H 3 + and CO toward the Galactic center

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  1. Spectroscopy of H3+ and CO toward the Galactic center Takeshi Oka, Christopher P. Morong,Department of Astronomy And Astrophysics and Department of Chemistry University of Chicago Thomas R. Geballe, Gemini Observatory, Hilo, Hawaii Miwa Goto, Max Planck Institute for Astronomy, Heidelberg, Germany Tomonori Usuda, Kumiko S. Usuda, Subaru Telescope, Hilo Hawaii Nicholas Indriolo, Benjamin J. McCall, Department of Chemistry and Department of Astronomy, University of Illinois at Urbana-Champaign June 19, 2007 Columbus Meeting

  2. Inferred face-on view of the Central Molecular Zone The Expanding Molecular Ring 130 pc 200 pc EMR 100 km s-1 145 km s-1 Sawada, Hasegawa, Handa, Cohen, MNRAS 349, 1167 (2004) Oka, Hasegawa, Sato, Tsuboi, Miyazaki, ApJS 118, 455 (1998) Scoville, ApJ 175, L127 (1972)

  3. Telescope and spectrometer 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

  4. The ideal rotational levels of H3+ Breaking Symmetry OrthoI = 3/2 J ParaI = 1/2 Metastable 8 hrs (3,3) 16 hrs μ (2,2) 361 K 20.4 days Unstable Critical Density 200 cm-3 27.2 days Ground (1,1) K Collision H3+ + H2→ (H5+)* → H3+ + H2 Interstellar NH3Oka, Shimizu, Shimizu, Watson, ApJ 165, L15 (1971) Interstellar H3+ Pan, Oka, ApJ 305, 518 (1986) Oka, Epp, ApJ 613, 349 (2004)

  5. Spectroscopy (1,1) ground (3,3) metastable (2,2) unstable 130 pc 100 km s-1 CO J = 1 Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

  6. Dimension of the discovered gas 7.3 ×10-8 cm3/s 1.6 ×10-4 1 ζL = 2 keN(H3+) (nC/nH)SV RX / f 3.1 ×1015 cm-2 3 - 10 COBE DIRBE Sodroski et al ApJ 452, 262 (1995) ζL = (2.5 – 8.4) ×105 cm/s L (pc) ζ (s-1) 120 pc 10-16 (0.8 - 2.1) k 10-1580 - 210 100 km s-1 Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

  7. 8 stars within 30 pc from GC all show high T and low n (2,2) densitometer (1,1) ground level (3,3) thermometer T = 220 - 400 K n ≤ 100 cm-3 (2,2) densitometer (1,1) ground level (3,3) thermometer

  8. All stars: high N(H3+) and hence high ζL R(2, 2)l R(1, 1)l Q(1, 0) Q(1, 1) R(3, 3)l R(1, 0)+R(1, 1)u R(2, 2)l R(1, 1)l Q(1, 0) Q(1, 1) R(3, 3)l R(1, 0)+R(1, 1)u N(H3+) = (2.3 - 4.5) × 1015 cm-2 L ≥ 60 – 120 pc for RX = 3 and ζ= 10-15 s-1

  9. Enter a new category of gas in the CMZ ? 0.8 107 K ? 0.1 106 K 10 cm-3 250 K102 cm-3 Warm and diffuse gas 0.1 102 K 104 cm-3 0.01 Lazio & Cordes, ApJ 505, 715 (1998) that is incompatible with two other gases

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

  11. The hyper-strong radio scattering caused by folded magnetic field rather than hot electrons? Folded fields as the source of extreme radio-wave scattering in the Galactic center Goldreich and Sridhar, ApJ 640, L159 (2006)

  12. Summary Spectroscopy of H3+ has revealed a new category of gas in the Central Molecular Zone with high temperature (~ 250 K) and low density ( ≤ 100 cm-3) with a large volume filling factor (f ~ 1). The finding drastically change the previous picture of the gas in the Central Molecular Zone. We are in the process of observing a wider region of the Central Molecular Zone. We need bright YSO’s!

  13. ζ= 10-17s-1 ζ= 10-17s-1 Harvey Liszt Phil. Trans. R. Soc. A 364, 3049 (2006)

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