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Warm Molecular Gas in Galaxies

International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005. Warm Molecular Gas in Galaxies. Rui-Qing Mao ( 毛瑞青 ) (Purple Mountain Observatory, Nanjing) C. Henkel (MPIfR) R. Mauersberger (IRAM) Dinh-Van-Trung (ASIAA).

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Warm Molecular Gas in Galaxies

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  1. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Warm Molecular Gas in Galaxies Rui-Qing Mao (毛瑞青) (Purple Mountain Observatory, Nanjing) C. Henkel (MPIfR) R. Mauersberger (IRAM) Dinh-Van-Trung (ASIAA)

  2. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Introduction:CO as a tracer of H2 in galaxies • Lower lying CO rotational line transitions are often used as tracers of H2. • CO(1-0), (2-1) surveys in galaxies • Young et al. (1995) 300 galaxies @ FCRAO • Braine & Combes (1992) 81 spirals @ IRAM-30m • … • CO is a good tracer of density waves, spirals, bars, rings. • High spatial resolution CO(1-0) surveys in galaxies • BIMA-SONG (Regan et al. 2001; Helfer et al. 2003) • NUGA (S. García-Burillo F. Combes et al) • NMA (Sakamoto et al. 1999)

  3. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Introduction: Is CO a Good Tracer ofSF in galaxies? Gao & Solomon (2004 ApJL) LHCN ~ LIR tightlinear correlation  Star formation driven LIR CO(1-0): poor tracer?

  4. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Introduction:How about sub-mm CO lines? • Better tracers for the warmer/denser molecular gas • R31 = ICO(3-2)/ICO(1-0) is more sensitive to the excitation of molecular gas than R21 = ICO(2-1)/ICO(1-0) • R31 is expected to be peaked in regions of active SF • High J CO lines will put more constraints to the excitation of molecular gas LVG model of R31

  5. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Introduction:M82 as an example • Bulk of CO emission is from diffused warm molecular gas • Two components: • dense cloud cores + diffused interclouds PDR model: ‘low’ and ‘high’ Excitation components The HHT CO(7-6) map of M82 LVG model: T=60-130 K n=103.3-3.9 cm-3 (Mao et al. 2000 A&A)

  6. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Introduction:CO SED • M82 CO(7-6): first time the weakening in CO SED • The CO SED turnover can serve as an indicator of gas excitation M82, NGC 253: 6-5 Henize 2-10, BR1202-0725(z=4.7), Cloverleaf (z=2.6): >7-6 SMM J16359+6612: 5-4 Weiss et al. 2005 astro-ph

  7. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Introduction:Extragalactic CO(3-2) surveys • Devereux et al. (1994) 7 starbursts; <R31>=0.64+/-0.06 • Mauersberger et al. (1999) • 28 nearby galaxies + 1 ULIRG; <R31>=0.63 (0.2-0.7) • Dumke et al. (2001) Mapping • Meier et al. (2001) 8 Dwarf starbursts; <R31>=0.60+/-0.06 • Yao et al. (2003) • 60 SLUGS cz  1900 km s-1; S60m  5.24 Jy; LFIR 1010LO • <R31>=0.66 • Vila-vilaro B. et al. (2003) 10 eraly-type galaxies • Hafok et al. (2003) 16 in Virgo Cluster; <R31>=0.14-0.35 • Narayanan et al. (2005) 15 Starbursts + (U)LIRGs

  8. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey 0. Motivations • What’s the general properties of warm molecular gas? • Can CO(3-2) be a good tracer of SF? • Can R31 be a good tracer of the excitation of molecular gas? • Any correlation between R31 and LIR, Hubble type, IR colors, merging sequence?

  9. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) SurveyI. Observations The Telescope: @ D=10.5 m @  = 22" at 345 GHz @ 3100m The Sample:120 @ Normal galaxies: 49 (S100m>50 Jy; Braine et al. 1993) @ Seyfert & LINER: 61 (Seyfert: 41; LINER:44; Sy+LINER:17) @ (U)LIRGs: 10 (Solomon et al. 1997) The Heinrich-Hertz-Telescope (HHT) @ Mt. Graham, Arizona @Early type: 23 @Virgo cluster galaxies: 10

  10. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey II. The spectra HHT CO(3-2) spectra of nearby galaxies.

  11. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey III. Detection rates • Detection rate -- 85/120 (71%) • Normal galaxies: 35/49 (71%) • Seyfert & LINER: 42/61 (69%) • (U)LIRGs: 8/10 (80%) • Early type: 11/23 (48%) • Virgo cluster galaxies: 8/10 (80%)

  12. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 CO(3-2) in LIRGsI. The Merging sequence total H2 content decreases as the projected separation of merger nuclei decreases (Gao & Solomon 1999) What about the excitation conditions of the molecular gas? Are these also affected by the interaction?

  13. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 II. The sample • The sample (16) (Lo et al. 1997;2000; Gao et al. 1997;2001) • Early Mergers • UGC 2369, Arp 303, UGC 8335, Arp 240, Arp 302, Arp 293, NGC 6670 • Intermediate Mergers • Arp 256, Mrk 848, Arp 55, NGC 7592 • Advanced Mergers • NGC 1614, NGC 5256, NGC 6090, NGC 3110, NGC 3147 • 16 LIRGs/22 pointings(5 overlaps with the SLUGS sample)

  14. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 III. The spectra 12 LIRGs/19 positions observed, all detected in CO(3-2)

  15. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey IV. The statistics

  16. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey IV. The statistics – R31 • Matching beam line ratios R31 (@ 22” , 51 galaxies) • <R31> =0.71+/-0.05, median=0.65 (Seyfert: <R13>=0.68 [0.4:1], ULIRG: <R13>=0.77 [0.4:1.2]) • No obvious correlation to LFIR, Hubble type, IR colors • Caution: (U)LIRGs: global, unresolved, R31 / Nearby starbursts: centers-only

  17. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 MappingR31 distribution in M82 V-band 12CO(1-0) Weiss et al. 2005 OVRO + IRAM30m Mao et al. 2000 streamer/outflow regions • lower R31 than in the central molecular disk • gas properties are similar to the nuclear ‘low’ excitation components

  18. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 CO SED of M82 Weiss et al. 2005 A&A 3x3 kpc Shift to cosmological distance: M82(total) (U)LIRGs & @high z

  19. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 High Resolution SMA CO(3-2) in M51 • Strong central concentration • Weak north-west arm • High line ratio: I32/I10 ~ 2 •  hot and dense mol. Gas • High R31 in outflow and shocked gas around SNRs in the MW •  gas dynamics around the Seyfert 2 nucleus •  heating by the central AGN? • Common for Seyfert galaxies? • Looking for more Seyfert (Matsushita et al. 2004)

  20. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR

  21. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR

  22. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR ULIRGs LIRGs

  23. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR Almost linear ULIRGs LIRGs 28 nearby gals: log10LCO(3-2) = -3.44 + 1.08 log10LFIR (Mauersberger et al. 1999) 60 SLUGS: log10LCO(3-2) = -2.4+/-0.5 + 0.70+/- 0.04 log10LFIR (Yao et al. 2004 ) 14(U)LIRGs+SLUGS: log10LCO(3-2) = -3.56 + 1.09 log10LFIR (Narayanan et al. astro-ph/0504412) 0.58 for CO(1-0)

  24. International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005 Summary • Almost linear correlation of LCO(3-2)-LFIR • With a power of 0.95 • CO(3-2) can trace warm-dense star forming gas • <R31> =0.71, median=0.65 • No obvious correlations are found between R31 and Hubble type, LFIR, infrared colors at 22” resolution • Mapping is needed for the nearby galaxies to make their R31 compared to that of (U)LIRGs

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