Revelation of a vast amount of warm (~ 250 K) and diffuse (≤ 100 cm -3 ) gas and high ionization rate (ζ > s -1 ) in the Central Molecular Zone by the Infrared Spectrum of H 3 + Takeshi Oka Department of Astronomy and Astrophysics and Department of Chemistry The Enrico Fermi Institute, University of Chicago Star formation under extreme conditions: the Galactic center at the Besançon Observatory, December 7, 2010 Tom Geballe Gemini Observatory Miwa Goto Max-Planck Institut für Astronomie
2005 Revelation of warm and diffuse gass near GC Oka, Geballe, Goto, Usuda, McCall, ApJ 632, High H 3 + abundance in the Galactic center H 3 +, the new astrophysical probe Oka, Phys. Rev. Lett. 45, 531 Laboratory Spectrum 1996 Geballe, Oka, Nature 384, 334 Interstellar H 3 +, Discovery, Dense Clouds H H2H2 H3+H Metastable H 3 +, Discovery, Galactic center Goto, McCall, Geballe, Oka, et al. PASJ 54, HC 5 N, HC 7 N, HC 9 N 2008 Ubiquity Central 30 pc of the Galactic center Goto, Geballe, Oka, et al. ApJ 688, 306 T.G Exploring wider regions of the Galactic center Geballe, Oka, ApJ, 709, L70
Telescopes and spectrometers Telescope D Spectrom. λ/Δλ UKIRT 3.8 m CGS4 40,000 Mauna Kea 1982 Subaru 8.2 m IRCS 20,000 Mauna Kea 2000 Gemini South 8 m Phoenix 60,000 Cerro Pachon 2003 VLT 8.2 m CRIRES 100,000 Cerro Paranal 2006 Gemini North 8 m GENIRS 18,000 Mauna Kea 2011 Subaru UKIRT Gemini South VLT Gemini North
Quintuplet Cluster 1° × 1° 140 pc × 140 pc Super-massive clusters GCS 3-2
High abundance of H 3 + in the CMZ CMZ R(1, 1) u R(1, 0) T. R. Geballe, Phil. Trans. Roy. Soc. Lond. A358, 2503 (2000) 3 × cm % 400 pc
(J, K) = (3, 3) metastable H 3 +, the fingerprint of GC Metastable 27.2 days 20.4 days Ortho I = 3/2 Para I = 1/2 J K 16 hrs 8 hrs (3,3) (2,2) (1,1) Pan and Oka, 1987, ApJ, 305, 518 (1,0) Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka, 2002, PASJ 54, K CO J = 1 (2,2) unstable (3,3) metastable (1,1) ground T ~ 250 K n ≤ 100 cm -3 Oka, Geballe, Goto, Usuda, McCall, 2005, ApJ, 632, 882 Spontaneous breakdown of symmetry
Ubiquity of H 3 + Sgr A* to 30 pc East 30 pc
1° × 1° 140 pc × 140 pc Super-massive clusters
Search for bright and hot stars in the CMZ GLIMPSE Point Source Catalogue of the Spitzer Space Telescope, L to M Ramírez et al. 2008, ApJS, 175, 147 2MASS photometry at J, H, and K band ̲ s Skrutskie et al. 2006, AJ, 131, 1163 ~ 2,000,000 stars L < 7.5 ~ 3,000 stars (J – K)/(K – L) < 2.5K - L > 1.5J - K > 5 ~ 300 stars Low res. CO first overtone, 2.2 – 2.4μm Candidate stars Selected stars High res. H 3 + and CO spectroscopy brightness youth hotness location - 1.2º < ℓ - ℓº < 1.2º- 0.1º < b - bº < 1.0 º
The CO test Old (late-type) cool stars are useless Bright, young, hot stars are scarce
New bright and hot dust embedded stars suitable for H 3 + spectroscopy Geballe and Oka, ApJ, 709, L70-73 (2010)
Two sightlines with remarkable H 3 + spectrum α ι Geballe and Oka, ApJ, 709, L70-73 (2010) 0 – 30 pc EastQuintuplet, α, ι
Simple chemistry of H 3 + → ·L Destruction H e → H + H + H Production H 2 → H e H H 2 →H + H 3 + L = 2 k e N(H 3 + ) (n C /n H ) SV R X / f 7.3 ×10 -8 cm 3 /s1.6 × ( ) ×10 15 cm -2 3 ( L) min = (1.3 – 4.3) ×10 5 cm/s L s -1 (0.4 – 1.4) kpc s pc Goto, Usuda, Nagata, Geballe, Indriolo, McCall, Suto, Henning, Morong, and Oka, ApJ, 668, 306 (2008) dn(H 3 + )/dt = n(H 2 ) = k e n(H 3 + )n(e)
Lazio & Cordes, ApJ, 505, 715 (1998) 80% K 10% K n e 10 cm -3 10% 50 K 10 4 cm -3 New category of gas in the CMZ f: Previous concept drastically changed T ~ 250 K n ~ 100 cm -3 L ~ 60 pc f ~30% ~ 1.5 × s -1 Schultheis et al. ApJ 495, 157 (2009) 2%
Chandra 20 pc × 20 pc (0.5 – 8) keV Muno et al. ApJ 589, 225 (2003) Warwick, Sakano Decourchelle (2006) Revnivtsev et al. (2006) X-ray: Chandra comes to rescue
Remarkable similarity between velocity profiles of H 3 + toward Iota and H 2 O +, CH + toward Sgr B2 Herschel observations of ortho- and para- oxidaniumyl (H 2 O + ) in spiral arm clouds toward Sgr B 2 (M) ⋆ P. Schilke,1,2 C. Comito,2 H. S. P. M¨uller,1 E. A. Bergin,3 E. Herbst,14 D. C. Lis,4 D. A. Neufeld,20 T. G. Phillips,4 T. A. Bell,4 G.A. Blake5 E. Caux,6,7 C. Ceccarelli,8 J. Cernicharo,9 N. R. Crockett,3 F. Daniel,9,10 M.-L. Dubernet,11,12 M. Emprechtinger,4 P. Encrenaz,10 M. Gerin,10 T. F. Giesen,1 J. R. Goicoechea,9 P. F. Goldsmith,13 H. Gupta,13 C. Joblin,6,7 D. Johnstone,15 W. D. Langer13 W. B. Latter16 S. D. Lord,16 S. Maret,8 P. G. Martin,17 G. J. Melnick,18 K. M. Menten,2 P. Morris,16 J. A. Murphy,19 V. Ossenkopf,12,21 J. C. Pearson,13 M. P´erault,10 R. Plume,22 S.-L. Qin,13 S. Schlemmer,1 J. Stutzki,1 N. Trappe,19 F. F. S. van der Tak,21 C. Vastel,6,7 S. Wang,3 H. W. Yorke,13 S. Yu,13 N. Erickson,25 F.W. Maiwald,13 J. Kooi,4 A. Karpov,4 J. Zmuidzinas,4 A. Boogert,4 R. Schieder,1 and P. Zaal21 A&A June Geballe & Oka, 2010, ApJ, 709, L70 H 3 + R(1,1) l H 2 O ← 0 00 H 2 O ← pc 3 kpcScutum Sgittarius E. Falgarone et al. 2010
NH 3 Metastable rotational levels J K NH 3 ΔK = 0
J K NH 3 NH 3 Metastable rotational levels Δk = 3
Metastable rotational levels J NH 3 μ T. Oka, F. O. Shimizu, T. Shimizu, J. K. G. Watson, ApJ 165, L15 (1971) 50 years Δk = years
H 3 + is simpler J Δk = 3 H3+H3+ Non-polar No inversion