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H 3 +

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  1. H3+

  2. H3+, a new astrophysical probe: Revelation of warm and diffuse gas near the Galactic center Takeshi Oka Department of Astronomy and Astrophysics and Department of Chemistry, The Enrico Fermi Institute The University of Chicago Thomas R. GeballeGemini Observatory Miwa GotoMax Planck Institute for Astronomy Tomonori UsudaSubaru Telescope Benjamin J. McCallUniversity of Illinois, Urbana-Champaign Tetsuya Nagata Kyoto University Tomoharu Oka University of Tokyo Farhad Yusef-Zadeh Northwestern University Harvey Liszt National Radio Astronomy Observatory June 27, 2007 CSO

  3. Thumbnail sketch of H3+ p p Simplest polyatomic molecule c.r. H 1951 Simple chemistry H2→ H2+ + e H2+ + H2 → H + H3+ H2 CO Initiator of interstellar chemistry H3++ O → H2 + OH+ 1970 X(H3+)diffuse ~ 10X(H3+)dense Powerful informant of: Cosmic ray ionization rate ζ Temperature T density n Radial length of clouds L H3+ 1996 + ζL = 2 keN(H3+) (nC/nH)

  4. Progress of H3+observation 1989 - 95 1996 Interstellar H3+, Discovery Geballe, Oka, Nature 384, 334 ζdiffuse~!0 ζdense 1998 – 2002 Ubiquity, Dense and Diffuse Clouds McCall, Geballe, Hinkle, Oka 1975 1980 Laboratory Spectrum Oka, PRL. 45, 531 2002 Metastable H3+, Discovery Goto, McCall,Geballe, Usuda, Kobayashi, Terada, OkaPASJ, 54, 951 • Hot and Diffuse Clouds near GC Probed by Metastable H3+ • Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882

  5. GCS3-2 Inferred face-on view of the Central Molecular Zone Quintuplet 130 pc 130 pc 100 km s-1 100 km s-1 Sawada, Hasegawa, Handa, Cohen, MNRAS 349, 1167 (2004) Oka, Hasegawa, Sato, Tsuboi, Miyazaki, ApJS 118, 455 (1998)

  6. Telescope and spectrometer UKIRT 3.8 m CGS4 8 km s-1 Mauna Kea 1982 Subaru8.2 m IRCS 15 km s-1 Mauna Kea 2000 Gemini South 8 m Phoenix 5 km s-1 Cerro Pachon 2003 VLT 8.2 m CRIRES ≤3 km s-1 Cerro Paranal 2006

  7. 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)

  8. Central Molecular Zone is the Treasure Houseof H3+ R(1, 1)u R(1, 0) N(H3+) = 4.4 × 1015 cm-2 N(H3+) = 3.8 × 1014 cm-2 L = 21 pc Geballe Phil. Trans. RSL A358, 2503 (2000)

  9. Spectroscopy (1,1) ground (3,3) metastable T = 250 K (2,2) unstable 130 pc n≤ 100 cm-3 100 km s-1 CO J = 1 Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

  10. L (pc) ζ (s-1) 10-16 (0.8 - 2.1) k 10-1580 - 210 Dimension of the discovered gas 7.3 ×10-8 cm3/s 1.6 ×10-4 ζL = 2 keN(H3+) (nC/nH)SV RX 3.1 ×1015 cm-2 3 - 10 COBE DIRBE Sodroski et al ApJ 452, 262 (1995) ζL = (2.5 – 8.4) ×105 cm/s 130 pc 100 km s-1 Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

  11. 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

  12. 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

  13. 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 Lazio & Cordes, ApJ 505, 715 (1998) that is incompatible with two other gases

  14. 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)

  15. X-ray sources diffuse gas or point source? Suzaku Dec. 6, 2006 Mostly diffuse Mostly discrete Koyama, Makishima, Tanaka, Tsunemi, 1986 Koyama, Awaki, Kunieda, Takano, et al., 1989 Koyama, Maeda, Sonobe, Takeshima, et al. 1996 Tanaka, 2002 Wang, Gotthelf, Lang, 2002 Muno, Baganoff, Bautz, Brandt, et al. 2003 Muno, Baganoff, Bautz, Brandt, et al. 2004 Ebisawa, et al., 2005 Warwick, Sakano, Decourchelle, 2006 Revnivtsev, Sazonov, Gilfanov, et al. 2006 Koyama et al. 2007

  16. 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)

  17. 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). CO Oka, Hasegawa, Hayashi, Handa, Sakamoto, ApJ 493, 730 (1998) Dahmen, Hüttemeister, Wilson, Mauersberger, A&A 331, 959 (1998) H2Rodriguez-Fernandez, Martin-Pintad, Fuente, et al. A&A365, 174 (2001) CH Magnani, Zelenik, Dame, Engebreth, ApJ 636, 267 (2006) 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!