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Star formation under extreme conditions: the Galactic center

Revelation of a vast amount of warm (~ 250 K) and diffuse (≤ 100 cm -3 ) gas and high ionization rate ( ζ > 10 -15 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

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Star formation under extreme conditions: the Galactic center

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  1. Revelation of a vast amount of warm (~ 250 K) and diffuse (≤ 100 cm-3)gas and high ionization rate (ζ> 10-15 s-1) in the Central Molecular Zone by the Infrared Spectrum of H3+ Takeshi Oka Department of Astronomy and Astrophysics and Department of Chemistry The Enrico Fermi Institute, University of Chicago Tom Geballe Gemini Observatory Miwa Goto Max-Planck Institut für Astronomie Star formation under extreme conditions: the Galactic center at the Besançon Observatory, December 7, 2010

  2. H3+, the new astrophysical probe H 1975HC5N, HC7N, HC9N 1951 1980 Laboratory Spectrum Oka, Phys. Rev. Lett. 45, 531 T.G. H2 1989 - 95 1970 1973 1996 Interstellar H3+, Discovery, Dense Clouds Geballe, Oka, Nature 384, 334 1999 High H3+ abundance in the Galactic center H3+ 2002 Metastable H3+, Discovery, Galactic center Goto, McCall, Geballe, Oka, et al. PASJ 54, 951 1996 + • Revelation of warm and diffuse gass near GC • Oka, Geballe, Goto, Usuda, McCall, ApJ 632, 882 2008 Ubiquity Central 30 pc of the Galactic center Goto, Geballe, Oka, et al. ApJ 688, 306 2010 Exploring wider regions of the Galactic center Geballe, Oka, ApJ, 709, L70

  3. Telescopes and spectrometers Telescope D Spectrom. λ/Δλ 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 Gemini North 8 m GENIRS 18,000 Mauna Kea 2011 Gemini North Gemini South Subaru UKIRT VLT

  4. Super-massive clusters Quintuplet Cluster GCS 3-2 1° × 1° 140 pc × 140 pc

  5. High abundance of H3+ in the CMZ R(1, 1)u R(1, 0) 3 × 1014 cm-2 10-5 10% T. R. Geballe, Phil. Trans. Roy. Soc. Lond. A358, 2503 (2000) CMZ 400 pc

  6. (J, K) = (3,3) metastable H3+, the fingerprint of GC Goto, McCall, Geballe, Usuda, Kobayashi, Terada, Oka, 2002, PASJ 54, 951 Spontaneous breakdown of symmetry (1,1) ground ParaI = 1/2 J OrthoI = 3/2 (3,3)metastable T ~ 250 K 8 hrs Metastable (3,3) 16 hrs (2,2) unstable n ≤ 100 cm-3 (2,2) 361 K 20.4 days (1,0) 27.2 days CO J = 1 (1,1) K Pan and Oka, 1987, ApJ, 305, 518 Oka, Geballe, Goto, Usuda, McCall, 2005, ApJ, 632, 882

  7. Ubiquity of H3+ Sgr A* to 30 pc East 30 pc

  8. Super-massive clusters 1° × 1° 140 pc × 140 pc

  9. 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 band̲s Skrutskie et al. 2006, AJ, 131, 1163 - 1.2º < ℓ - ℓº < 1.2º - 0.1º < b - bº < 1.0º ~ 2,000,000 stars brightness L < 7.5 ~ 3,000 stars youth J - K > 5 K - L > 1.5 (J –K)/(K – L)< 2.5 ~ 300 stars hotness Low res. CO first overtone, 2.2 – 2.4μm Candidate stars location High res. H3+ and CO spectroscopy Selected stars

  10. The CO test Old (late-type) cool stars are useless Bright, young, hot stars are scarce

  11. New bright and hot dust embedded stars suitable for H3+ spectroscopy Geballe and Oka, ApJ, 709, L70-73 (2010)

  12. Two sightlines with remarkable H3+ spectrum Quintuplet,α, ι 0 – 30 pc East α ι Geballe and Oka, ApJ, 709, L70-73 (2010)

  13. 7.3 ×10-8 cm3/s 1.6 ×10-4 1 (1.8-6.1) ×1015 cm-2 3 Simple chemistry of H3+ → ·L  ProductionH2→H2+ + e H2++ H2 →H + H3+ dn(H3+)/dt = n(H2) = ken(H3+)n(e) DestructionH3+ + e → H + H + H L = 2 keN(H3+) (nC/nH)SV RX / f (L)min = (1.3 – 4.3) ×105 cm/s  L 10-16 s-1 (0.4 – 1.4) kpc 10-15 s-140 - 140 pc Goto, Usuda, Nagata, Geballe, Indriolo, McCall, Suto, Henning, Morong, and Oka, ApJ, 668, 306 (2008)

  14. New category of gas in the CMZ Previous concept drastically changed T ~ 250 K n ~ 100 cm-3 L ~ 60 pc f ~30% ~ 1.5 × 1015 s-1 Schultheis et al. ApJ 495, 157 (2009) f: 80% 107-8 K 10% 104-6 K ne10 cm-3 Lazio & Cordes, ApJ, 505, 715 (1998) 10% 50 K 104 cm-3 2%

  15. 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)

  16. Remarkable similarity between velocity profiles of H3+ toward Iota and H2O+, CH+ toward Sgr B2 Herschel observations of ortho- and para-oxidaniumyl (H2O+) in spiral arm clouds toward Sgr B2(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 3 kpc Scutum Sgittarius H2O+ 110← 101 H3+ R(1,1)l H2O+ 111← 000 A&A June 22 2010 E. Falgarone et al. 2010 Geballe & Oka, 2010, ApJ, 709, L70 17 pc

  17. NH3Metastable rotational levels J NH3 3 2 ΔK = 0 1 K 0 0 1 2 3

  18. NH3Metastable rotational levels J NH3 3 2 Δk = 3 1 K 0 0 1 2 3

  19. Metastable rotational levels J NH3 3 50 years 2 μ 200 years 1 Δk = 3 0 T. Oka, F. O. Shimizu, T. Shimizu, J. K. G. Watson, ApJ 165, L15 (1971)

  20. H3+ is simpler Non-polar No inversion H3+ J 3 2 1 0 Δk = 3

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