銀河中心の H ３ ＋ Department of Astronomy and Astrophysics Department of Chemistry and The Enrico Fermi Institute, The University of Chicago 岡 武史 岡コロキウム 東京工業大学、 2007 年 10 月 19 日 Thomas R. Geballe Gemini Observatory 後藤 美和 Max Planck Institute for Astronomy 臼田 知史 Subaru Telescope Benjamin J. McCall University of Illinois, Urbana-Champaign

The eventful 月 29 日 Doppler shift II 八ヶ岳、剣、立山 9 月 25 日 岡コロキウム 7 月 15 日 Doppler shift I 4 月 29 日 星間 H ３ ＋ 検出 Nature, 384,334 森野米三先生追悼記念講演会 第一回分子研フォラム The sigh of relief is audible round world of astronomy

N(H 3 + ) ~ 3  cm Surprise 1: H 3 + in diffuse cloud Cygnus OB2 No 12HD V = V = 6.86 Geballe, McCall, Hinkle, Oka, ApJ 510, 251 (1999)McCall et al. ApJ 567, 391 (2002)

Ubiquitous H 3 + Production : Cosmic Ray 0.6 primary particles cm -2 s -1 H 2 → H e - ζ n(H 2 ) ζ ~ 3 × s -1 H H 2 → H + H 3 + k L n(H 2 + )n(H 2 ) k L ~ cm 3 s -1 C.R. Destruction Dense Clouds (~10 4 cm -3 ) H CO → H 2 + HCO + Rate = k L n(H 3 + )n(CO) k L ~ cm 3 s -1 Diffuse Clouds (~ 10 2 cm -3 ) H e - → H + H + H Rate = k e n(H 3 + )n(e - ) k e ~ cm 3 s -1 n(H 3 + ) = [ζ/k L ][n(H 2 )/n(CO)] n(H 3 + ) = [ζ/k e ][n(H 2 )/n(e - )] 10 × ζ dense ~ ζ diffuse

Storage Ring Measurements 20 ns 45 ns electron beam H3+H3+ H, H 2 +Complete vibrational relaxation +Very simple experiment +Control H 3 + – e - impact energy -Rotationally hot ions produced -No rotational cooling in ring CRYRING McCall et al, Nature, 2003

Surprise 2 ： Central Molecular Zone Morris, Serabyn, ARA&A (1996) CMZ OH, H 2 CO, CO, CS, NH 3, HCN H3+H3+ Mezger, Duschl, Zylka, A&A Rev. (1996) R(1, 1) u R(1, 0) Geballe Phil. Trans. RSL A358, 2503 (2000) is the treasure house of H 3 +

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

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

Spectroscopy 130 pc 100 km s -1 Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka PASJ, 54, 951 (2002)

Surprise 4: 捨て札があれよあれよと すべて生き札となった （水村美苗） 霜田光一 二重共鳴 Collision Forbidden transitions 衝突にも選択率がある 分光学の選択率は破れる ΔK = 0 Δk = ± 3

Breaking Symmetry Interstellar NH 3 Oka, Shimizu, Shimizu, Watson, ApJ 165, L15 (1971) Interstellar H 3 + Pan, Oka, ApJ 305, 518 (1986) Metastable 27.2 days 20.4 days μ Critical Density 200 cm -3 Ortho I = 3/2 Para I = 1/2 J K Collision H H 2 → (H 5 + ) * → H H 2 16 hrs 8 hrs  ++ = uuu The ideal rotational levels of H 3 + (3,3) (2,2) Unstable (1,1) Ground 361 K

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

Discovery of high temperature (T ~ 250 K), low density (n ≤ 100 cm -3 ) clouds Oka & Epp, ApJ 613,349 (2004)

Gas in the CMZ : pre -H 3 + Lazio & Cordes, ApJ 505, 715 (1998) K K 10 cm K 10 4 cm pc × 30 pc 7 × 10 7 K Suzaku Dec. 6, 2006 Koyama et al. PASJ 59, S245 (2007) Surprise 5: Warm and diffuse gas

CO J = 1 (2,2) unstable (3,3) metastable (1,1) ground Spectroscopy Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 (2005)

Surprise 6: Extragalactic H 3 + Geballe, Goto, Usuda, Oka, McCall ApJ 644, 907 (2006) Z =

Chandra 20 pc × 20 pc (0.5 – 8) keV Muno et al. ApJ 589, 225 (2003) Warwick, Sakano Decourchelle (2006) Revnivtsev et al. (2006)