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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, 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)
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
Introduction: Is CO a Good Tracer of SF in galaxies?
LHCN ~ LIR tight linear correlation Star formation driven LIR
CO(1-0): poor tracer?
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
Gao & Solomon (2004 ApJL)
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
Ju 1 2 3 4 5 6 7Eu(K) 5.5 17 33 55 83 116 155nc(cm-
3)7.4•10
24.9•1
031.5•1
04… … … ~106
LVG model of R31
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
Bulk of CO emission is from diffused warm molecular gas Two components:
dense cloud cores + diffused interclouds
LVG model: T=60-130 K n=103.3-3.9 cm-3
PDR model: ‘low’ and ‘high’ Excitation components(Mao et al. 2000 A&A)
Introduction:M82 as an example
The HHT CO(7-6) map of M82
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International 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
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
Weiss et al. 2005 astro-ph
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; S60m 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
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
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?
HHT CO(3-2) Survey0. Motivations
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International 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 (S100m>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
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
HHT CO(3-2) spectra of
nearby galaxies.
HHT CO(3-2) SurveyII. The spectra
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
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) SurveyIII. Detection rates
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International 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?
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International 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)
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International 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)
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
0 2000 4000 6000 8000 10000 12000 140000
10
20
30
Nu
mb
er
of g
ala
xie
s
Velocity (km s-1)
7 8 9 10 11 120
10
20
30
Nu
mb
er
of g
ala
xie
slog(L/L
O)
HHT CO(3-2) SurveyIV. The statistics
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
0 50 100 150 2000
1
2
3
R3
1
D (Mpc)
8 9 10 11 12 13
0
1
2
3
N1068
Arp 193
N7679N1275
IIIZW35
N6240 Arp 220
Mrk 273
17208-0014N7469
N3077
Mrk 231
R3
1
log(L/LO)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50
5
10
15
20
Nu
mb
er
of g
ala
xie
s
R31
= I32
/ I10
HHT CO(3-2) SurveyIV. 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
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
0.0 0.5 1.0 1.5 2.00
2
4
6
8
10
Nu
mb
er
of
ga
laxi
es
R31
= I32
/ I10
MappingR31 distribution in M82
Weiss et al. 2005Mao et al. 2000
12CO(1-0)V-band
OVRO + IRAM30m
• lower R31 than in the central molecular disk• gas properties are similar to the nuclear ‘low’ excitation components
streamer/outflow regions
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
CO SED of M82
Shift to cosmological distance: M82(total) (U)LIRGs & @high z
Weiss et al. 2005 A&A
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
3x3 kpc
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)
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR
9 10 11 121.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
log10
LCO(3-2)
= -5.4+/-0.5 + 0.90+/-0.05 log10
LFIR
log 10
(LC
O(3
-2)/
[K k
m s
-1 M
pc2 ])
log10
(LFIR
/LO)
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
9 10 11 12 13
2
3
4
5
6
log10
LCO(3-2)
= -5.8+/-0.5 + 0.95+/-0.05log10L
FIR
lo
g 10(L
CO
(3-2
)/ [K
km
s-1 M
pc2 ])
log10
(LFIR
/LO)
HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
9 10 11 12 13
2
3
4
5
6
log10
LCO(3-2)
= -5.8+/-0.5 + 0.95+/-0.05log10L
FIR
lo
g 10(L
CO
(3-2
)/ [K
km
s-1 M
pc2 ])
log10
(LFIR
/LO)
HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR
LIRGsLIRGsULIRGsULIRGs
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
9 10 11 12 13
2
3
4
5
6
log10
LCO(3-2)
= -5.8+/-0.5 + 0.95+/-0.05log10L
FIR
lo
g 10(L
CO
(3-2
)/ [K
km
s-1 M
pc2 ])
log10
(LFIR
/LO)
HHT CO(3-2) Survey V. LCO(3-2) vs. LFIR
60 SLUGS: log10LCO(3-2) = -2.4+/-0.5 + 0.70+/- 0.04 log10LFIR (Yao et al.
2004 )
28 nearby gals: log10LCO(3-2) = -3.44 + 1.08 log10LFIR (Mauersberger et al. 1999)
0.58 for CO(1-0)
LIRGsLIRGsULIRGsULIRGs
Almost linear
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005
14(U)LIRGs+SLUGS: log10LCO(3-2) = -3.56 + 1.09 log10LFIR (Narayanan et al. astro-ph/0504412)
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
International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005International Workshop “Extreme Starburst: Near and Far” Lijiang, 14-21 August, 2005