1 / 28

A CO(3-2) Survey of Warm Molecular Gas in Nearby Galaxies

“Universe Probed by Radio” Sino-German Workshop on Radioastronomy, Kashi/Urumqi, Sept. 7-13, 2005. A CO(3-2) Survey of Warm Molecular Gas in Nearby Galaxies. Rui-Qing Mao ( 毛瑞青 ) (Purple Mountain Observatory, Nanjing) C. Henkel (MPIfR) R. Mauersberger (IRAM) Dinh-Van-Trung (ASIAA).

eadame
Download Presentation

A CO(3-2) Survey of Warm Molecular Gas in Nearby Galaxies

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. “Universe Probed by Radio” Sino-German Workshop on Radioastronomy, Kashi/Urumqi, Sept. 7-13, 2005 A CO(3-2) Survey of Warm Molecular Gas in Nearby Galaxies Rui-Qing Mao (毛瑞青) (Purple Mountain Observatory, Nanjing) C. Henkel (MPIfR) R. Mauersberger (IRAM) Dinh-Van-Trung (ASIAA)

  2. 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. 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. 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. Introduction:M82 as an example Mao, Henkel, Mauersberger et al. 2000 A&A Weiss et al. 2005 A&A

  6. 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. 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. Motivations • What’s the general properties of warm molecular gas in various galaxies? • 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. 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 (v<7000 km/s; Seyfert: 41; LINER:44; Sy+LINER:17) @ (U)LIRGs: 10 (Solomon et al. 1997) (Sy+LINER: 8; Sbrst: 1; UN: 1) The Heinrich-Hertz-Telescope (HHT) @ Mt. Graham, Arizona @Early type: 23 @Virgo cluster galaxies: 10

  10. Results I. The spectra HHT CO(3-2) spectra of nearby galaxies.

  11. Results II. 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. Results III. The statistics

  13. Results 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

  14. Mapping needed-R31 distribution in M82 Weiss et al. 2005 V-band 12CO(1-0) OVRO + IRAM30m Mao, Henkel, Mauersberger et al. 2000 streamer/outflow regions • lower R31 than in the central molecular disk • gas properties are similar to the nuclear ‘low’ excitation components

  15. Discussion-CO SED of M82 Weiss et al. 2005 A&A 3x3 kpc Shift to cosmological distance: M82(total) (U)LIRGs & @high z

  16. 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 ApJL)

  17. Results V. LCO(3-2) vs. LFIR

  18. Results V. LCO(3-2) vs. LFIR

  19. 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?

  20. CO(3-2) in LIRGsII. 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)

  21. CO(3-2) in LIRGsIII. The spectra 12 LIRGs/18 positions observed, all detected in CO(3-2)

  22. Results V. LCO(3-2) vs. LFIR

  23. Results V. LCO(3-2) vs. LFIR

  24. Results V. LCO(3-2) vs. LFIR ULIRGs LIRGs

  25. Results 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)

  26. Summary • Almost linear correlation of LCO(3-2)-LFIR @ 22” • 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

  27. “Cosmos probed by radio” Sino-German workshop on radioastronomy, Kashi/Urumqi, Sept. 7-13, 2005 @ High resolutionNGC6946 seen with the SMA • CO(2-1) in color • 2.4" x3.0" • Multiple arms • Gas lane along bar • CO(3-2) in contours • 0.7"x1.0" ！ • Streaming motion • Possible molecular nuclear mini-bar • The key issue is to understand the dynamics: ‘feeding the nucleus’ D=5.5 Mpc Mao R.-Q et al., (2005 in preparation)

  28. “Universe Probed by Radio” Sino-German workshop on radioastronomy, Kashi/Urumqi, Sept. 7-13, 2005

More Related