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From GMC-SNR interaction to gas-rich galaxy-galaxy merging

From GMC-SNR interaction to gas-rich galaxy-galaxy merging. Yu GAO Purple Mountain Observatory, Nanjing, China Chinese Academy of Sciences . SFR vs. M(H2): No Unique Slope:1, 1.4, 1.7?. H2-dominated LIRGs/ULIRGs. HI ~ H2. HI-dominated LSB galaxies.

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From GMC-SNR interaction to gas-rich galaxy-galaxy merging

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  1. From GMC-SNR interaction to gas-rich galaxy-galaxy merging Yu GAO Purple Mountain Observatory, Nanjing, China Chinese Academy of Sciences

  2. SFR vs. M(H2): No Unique Slope:1, 1.4, 1.7? H2-dominated LIRGs/ULIRGs HI ~ H2 HI-dominated LSB galaxies Extragalactic SF=CO until 90’s Gao & Solomon 2004b ApJ

  3. SF thresholds may simply reflect the change of the dominant cold gas phase in galaxies from HI ->H2 & from H2->denseH2 Bigiel’s talk @SFR50 Schruba+2011 ~linear in H2!

  4. Gao, Carilli, Solomon & Vanden Bout 2007 ApJ, 660, L93 13 HCN @high-z

  5. Dense H2 show the best correlation with SFR (linear Liu & Gao 2011). Liu & Gao 2011 arXiv:1106.2813 Poster by Liu+

  6. Bi-modal SF laws in high-z gals (Daddi+2010; Genzel+2010) also exist in local gals

  7. Introduction and Outline 1. R=CO/13CO line intensity ratios: R ~2-5 Galactic Ring Survey 13CO (Jackson+06; Simon+01) UMass-StonyBrook CO survey (Sanders+86), ~5-10 Galactic center GMCs + normal spirals, ~10-20 Starbursts (eg, Aalto+1995) ~30-50 (U)LIRGs(few 13CO published; Papadopoulos+11) high R10 associated with small, warmbut compact molecular cloudsof low to moderateoptical depth, or the high[12CO/13CO] abundance ratio 2. Best case studies: Arp220 (Greve+09; Matsushita+09), NGC6240(Greve+09; U+11) 3. Resolved measurements in Antennae galaxies (Gao+01; Zhu+03), Taffy (Gao+03; Braine+03; Zhu+07); nearby gals. (Tan+11) 4. Supernova remnant (SNR) IC 443: GMC-SNR interactions (Wang+Scoville92; Zhang+10) 5. Implications: the molecular gas conditions in (U)LIRGs

  8. 2. Best case studies Greve+09 R~43

  9. Matsushita+09

  10. Greve+09 R~45

  11. 3. Resolved measurements in ongoing mergers VLA 20cm on HST Very tight FIR-radio continuum correlation BIMA+12m CO on HST image

  12. Gao+01, SFE (20cm/CO) contour map

  13. Zhu+03 R32~15 R32~25

  14. Zhu+03 R21 ~20-30@overlap ~15@Nuclei

  15. Gao 2008 Zhang, Gao, Kong 2010 MNRAS

  16. 450um contours on 8um image 850um contours on CO image SCUBA: Zhu, Gao, Seaquist & Dunne 2007 CO: Gao, Zhu, Seaquist 2003

  17. R~15, 50 (The 12CO line intensities are divided by 10, Braine+03) HII

  18. Tan+11 arXiv1103.5540

  19. 1.4GHz Continuum CO (1-0) in Gem OB1 GMC Lee et al. 2008 4. Supernova remnant (SNR) IC 443 -- the JellyfishNebula Columnbia CO Survey Dame et al. 2001

  20. Simultaneous observations:12CO,13CO & C18O (1-0) Typical Tsys~180-300K (rms noise ~0.2K in 0.4 km/s) Total obs. points >1000, total spectra~7000, 2Months Beam size and sampling grid: ~ 55” (~1’) Gateway 2 Lhasa by sky train Array 3x3 + OTF 2011

  21. Zhang, Gao & Wang arXiv: 0911.4815

  22. Zhang, Gao & Wang arXiv: 0911.4815 70um and 160um overlaid with CO(1-0)

  23. Zhang, Gao & Wang arXiv: 0911.4815 HI and radio continuum images overlaid with CO(1-0)

  24. CO/13CO Line Ratio & FIR Maps [FeII], [SI], H2 0-0 S(0) [OI] [CII] + Dust? Spitzer 70 um Spitzer 160 um Spitzer 24 um 1. Line ratios are much higher in shocked regions than in the rest regions. 2. Line ratio maps in IC443 are strikingly well matched with the FIR images.

  25. SNR IC443 Yellow: 12CO Blue: 13CO Background: Spitzer 24μm Spectra Analysis

  26. 5. Implications to (U)LIRGs • Concentrated molecular gas of ~10^10Msun in ~1kpc (vs. >10 kpc 10^9 Msun H2 in the Galaxy) (~10^3) • Packed with dense cores (HCN-FIR) and even intercloud (or inter-dense-core) medium is highly molecular • SNe rates in ULIRGs ~100 times that of the Milky Way • Most dense cores are shocked by SNRs in ULIRGs (~10^5xMW) besides strong galaxy-galaxy collisions • Highly shocked regions higher R=CO/13CO in LIRGs • The abnormally high ratios of R (& CO/C18O) found in SNR IC443 of shock-origin are comparable to the observed values in starbursts and (U)LIRGs, likely implying their same physical origin. Gao & Solomon 04, Gao+07: Dense H2 Dense Cores

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