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) International Workshop “Extreme Starburst: Near and Far” Lijiang, August, 2005

Introduction: CO as a tracer of H 2 in galaxies Lower lying CO rotational line transitions are often used as tracers of H 2. CO(1-0), (2-1) surveys in galaxies Young et al. (1995) 300 FCRAO Braine & Combes (1992) 81 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)

Introduction: Is CO a Good Tracer of SF in galaxies? L HCN ~ L IR tight linear correlation  Star formation driven L IR CO(1-0): poor tracer? Gao & Solomon (2004 ApJL)

Introduction: How about sub-mm CO lines? Better tracers for the warmer/denser molecular gas R 31 = I CO(3-2) /I CO(1-0) is more sensitive to the excitation of molecular gas than R 21 = I CO(2-1) /I CO(1-0) R 31 is expected to be peaked in regions of active SF High J CO lines will put more constraints to the excitation of molecular gas JuJu E u (K) n c (cm -3 ) ………~10 6 LVG model of R 31

Bulk of CO emission is from diffused warm molecular gas Two components: dense cloud cores + diffused interclouds LVG model: T= K n= cm -3 PDR model: ‘low’ and ‘high’ Excitation components (Mao et al A&A) Introduction: M82 as an example The HHT CO(7-6) map of M82

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, BR (z=4.7), Cloverleaf (z=2.6): >7-6 SMM J : 5-4 Weiss et al astro-ph

Introduction: Extragalactic CO(3-2) surveys Devereux et al. (1994) 7 starbursts; =0.64 +/-0.06 Mauersberger et al. (1999) 28 nearby galaxies + 1 ULIRG; =0.63 ( ) Dumke et al. (2001) Mapping Meier et al. (2001) 8 Dwarf starbursts; =0.60 +/-0.06 Yao et al. (2003) 60 SLUGS cz  1900 km s -1 ; S 60  m  5.24 Jy; L FIR  L O =0.66 Vila-vilaro B. et al. (2003) 10 eraly-type galaxies Hafok et al. (2003) 16 in Virgo Cluster; = Narayanan et al. (2005) 15 Starbursts + (U)LIRGs

What’s the general properties of warm molecular gas? Can CO(3-2) be a good tracer of SF? Can R 31 be a good tracer of the excitation of molecular gas? Any correlation between R 31 and L IR, Hubble type, IR colors, merging sequence? HHT CO(3-2) Survey 0. Motivations

HHT CO(3-2) Survey I. Observations The D=10.5  = 22" at m The Sample: Normal galaxies: 49 (S 100  m >50 Jy; Braine et al. Seyfert & LINER: 61 (Seyfert: 41; LINER:44; (U)LIRGs: 10 (Solomon et al. 1997) The Heinrich-Hertz-Telescope Mt. Graham, type: cluster galaxies: 10

HHT CO(3-2) spectra of nearby galaxies. HHT CO(3-2) Survey II. The spectra

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%) HHT CO(3-2) Survey III. Detection rates

CO(3-2) in LIRGs I. The Merging sequence total H 2 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?

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 LIRGs/22 pointings (5 overlaps with the SLUGS sample)

III. The spectra 12 LIRGs/19 positions observed, all detected in CO(3-2)

HHT CO(3-2) Survey IV. The statistics

HHT CO(3-2) Survey IV. The statistics – R 31 ; Matching beam line ratios R 31 22”, 51 galaxies) ; =0.71 +/-0.05, median=0.65 (Seyfert: =0.68 [0.4:1], ULIRG: =0.77 [0.4:1.2]) ; No obvious correlation to L FIR, Hubble type, IR colors ; Caution: (U)LIRGs: global, unresolved, R 31 / Nearby starbursts: centers- only

Mapping R31 distribution in M82 Weiss et al Mao et al CO(1-0) V-band OVRO + IRAM30m lower R 31 than in the central molecular disk gas properties are similar to the nuclear ‘low’ excitation components streamer/outflow regions

CO SED of M82 Shift to cosmological distance: M82(total)  (U)LIRGs z Weiss et al A&A 3x3 kpc

High Resolution SMA CO(3-2) in M51 Strong central concentration Weak north-west arm High line ratio: I 32 /I 10 ~ 2  hot and dense mol. Gas High R 31 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)

HHT CO(3-2) Survey V. L CO(3-2) vs. L FIR

HHT CO(3-2) Survey V. L CO(3-2) vs. L FIR

HHT CO(3-2) Survey V. L CO(3-2) vs. L FIR LIRGs ULIRGs

HHT CO(3-2) Survey V. L CO(3-2) vs. L FIR 60 SLUGS: log 10 L CO(3-2) = / / log 10 L FIR (Yao et al ) 28 nearby gals: log 10 L CO(3-2) = log 10 L FIR (Mauersberger et al. 1999) 0.58 for CO(1-0) LIRGs ULIRGs Almost linear 14(U)LIRGs+SLUGS: log 10 L CO(3-2) = log 10 L FIR (Narayanan et al. astro-ph/ )

Summary Almost linear correlation of L CO(3-2) -L FIR With a power of 0.95 CO(3-2) can trace warm-dense star forming gas =0.71, median=0.65 No obvious correlations are found between R 31 and Hubble type, L FIR, infrared colors at 22” resolution Mapping is needed for the nearby galaxies to make their R 31 compared to that of (U)LIRGs