CI and CO in the spiral galaxies NGC 6946 and M 83

Israel, F. P.; Baas, F.

doi:10.1051/0004-6361:20010354

Cited by 85 publications

(114 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For those galaxies that were not mapped in [CI], we have used the J = 4-3 12 CO maps to estimate the convolved [CI] intensity and the total luminosity by assuming identical [CI] and J = 4-3 12 CO distributions. This was shown to be the case for M 83 and NGC 6946 (Petitpas & Wilson 1998;Israel & Baas 2001), but we have further verified the validity of this assumption for all galaxies that were mapped in both [CI] and J = 4-3 12 CO. Values obtained in this way are given in parentheses in Table 2.…”

Section: Resultssupporting

confidence: 76%

“…For half of the galaxy sample, the distribution of [CI] was mapped beyond the central position (cf. (Israel & Baas 2001); the remaining maps will be discussed in forthcoming papers. In the meantime, we have used the information contained in the maps to convolve the fullresolution central [CI] intensities (Col. 4 of Table 2) to [CI] intensities (Col. 5) appropriate to the twice larger beamsize of the J = 2-1 13 CO observations.…”

Section: Resultsmentioning

confidence: 99%

“…Beyond the Local Group, i.e. at distances larger than 1 Mpc, [CI] has been mapped in bright galaxies such as IC 342 (Büttgenbach et al 1992), M 82 (Schilke et al 1993;White et al 1994;Stutzki et al 1997) and NGC 253 (Israel et al 1995;Harrison et al 1995), as well as M 83 (Petitpas & Wilson 1998;Israel & Baas 2001) and NGC 6946 (Israel & Baas 2001). A survey of 13 galaxies, including limited Gerin & Phillips (2000).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Neutral atomic carbon in centers of galaxies

Israel

Baas

2002

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. We present measurements of the emission from the centers of fifteen spiral galaxies in the 3 P1-3 P0 [CI] fine-structure transition at 492 GHz. Observed galaxy centers range from quiescent to starburst to active. The intensities of neutral carbon, the J = 2-1 transition of 13 CO and the J = 4-3 transition of 12 CO are compared in matched beams. Most galaxy centers emit more strongly in [CI] than in 13 CO, completely unlike the situation pertaining to Galactic molecular cloud regions.[CI] intensities are lower than, but nevertheless comparable to J = 4-3 12 CO intensities, again rather different from Galactic sources. The ratio of [CI] to 13 CO increases with the central [CI] luminosity of a galaxy; it is lowest for quiescent and mild starburst centers, and highest for strong starburst centers and active nuclei. Comparison with radiative transfer model calculations shows that most observed galaxy centers have neutral carbon abundances close to, or exceeding, carbon monoxide abundances, rather independent from the assumed model gas parameters. The same models suggest that the emission from neutral carbon and carbon monoxide, if assumed to originate in the same volumes, arises from a warm and dense gas rather than a hot and tenuous, or a cold and very dense gas. The observed [CI] intensities together with literature [CII] line and far-infrared continuum data likewise suggest that a significant fraction of the emission originates in medium-density gas (n = 10 3 -10 4 cm −3 ), subjected to radiation fields of various strengths.

show abstract

Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Neutral atomic carbon in centers of galaxies

Israel

Baas

2002

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Limits to the validity of this method come from the fact that the weak metallicity dependence used here for X CO is based on CO interferometric measurements, which may underestimate cloud sizes and hence invalidate the used scaling law (Israel & Baas 2001). The metallicity in M 33 however has a scatter at each radius that is larger than the overall observed radial gradient: a stronger metallicity dependence can be considered only if the metallicity at each source location is known.…”

Section: Radially Varying X Comentioning

confidence: 99%

On the nature of faint mid-infrared sources in M 33

Corbelli

Giovanardi

Palla

et al. 2011

A&A

View full text Add to dashboard Cite

Aims. We investigate the nature of 24 μm sources in M 33 that have weak or no associated Hα emission. Both bright evolved stars and embedded star-forming regions are visible as compact infrared sources in the 8 and 24 μm Spitzer maps of M 33 and contribute to the more diffuse and faint emission in these bands. Can we distinguish the two populations? Methods. We carry out deep CO J = 2-1 and J = 1-0 line searches at the location of 18 compact mid-IR sources and two optically selected ones to unveil an ongoing star formation process throughout the disk of M 33. In the absence of high-resolution CO maps we use different assumptions to estimate cloud masses from pointed observations. We also analyze if the spectral energy distribution and mid-IR colors can be used to discriminate between evolved stars and star-forming regions.Results. Molecular emission is detected at the location of 17 sources at the level of 0.3 K km s −1 or higher in at least one of the CO rotational lines. Even though the number of giant molecular clouds drops beyond 4 kpc in M 33, our deep observations reveal that clouds of smaller mass are common out to 6.8 kpc. Estimated cloud masses range between 10 4 and 10 5 M , assuming likely values of the CO-to-H 2 conversion factor and virial equilibrium. Sources that are known to be evolved variable stars show weaker or undetectable CO lines. Evolved stars occupy a well defined region of the IRAC color-color diagrams. Star-forming regions are scattered throughout a larger area, even though the bulk of the distribution has different IRAC colors than evolved variable stars. We estimate that about half of the 24 μm sources without an Hα counterpart are genuine embedded star-forming regions. Sources with faint but compact Hα emission have an incomplete Initial Mass Function (IMF) at the high-mass end and are compatible with a population of young clusters with a stochastically sampled, universal IMF.

show abstract

“…Such observations can be performed from high altitude dry mountain sites, such as the Mauna Kea summit in Hawaii. Previous studies using the James Clerk Maxwell Telescope (JCMT) and the CSO have shown that the 12 CO(4−3) line is generally bright in galaxy nuclei (Guesten et al 1993;Israel et al 1995;Israel & Baas 2001Kramer et al 2005, ...). Much less information is available on the other high frequency CO lines.…”

Section: Introductionmentioning

confidence: 99%

A survey of submillimeter C and CO lines in nearby galaxies

Bayet¹,

Gérin²,

Phillips

et al. 2006

A&A

130

View full text Add to dashboard Cite

Aims. While the search for molecular gas in distant galaxies is based on the detection of submillimeter CO rotational lines, the current CO surveys of nearby galaxies are restricted to the millimeter CO lines. The submillimeter CO lines are formed in warm and dense molecular gas and are therefore sensitive to the physical conditions whereas the CO (J = 1 → 0) line is a tracer of the total molecular gas mass. In order to be able to compare the properties of molecular gas in nearby and distant galaxies, we have observed C and CO submillimeter lines (including the 12 CO(6−5) and 12 CO(7−6) lines) in a sample of nearby galaxies using the Caltech Submillimeter Observatory (CSO). Methods. We have obtained a complete view of the CO cooling curve (also called CO spectral energy distribution) by combining the submillimeter CSO data with previous observations found in the literature. We made use of Large Velocity Gradient (LVG) models to analyse the observed CO cooling curve, predict CO line intensities from J = 1 → 0 to J = 15 → 14 in the studied galaxies, and derive the physical properties of the warm and dense molecular gas : the kinetic temperature (T K ); the gas density (n(H 2 )); the CO column density divided by the line width N( 12 CO)/∆v. The predictions for the line intensities and for the total CO cooling power, obtained from LVG modelling have been compared with predictions from Photo Dissociation Regions (PDR) models. Results. We show how the CO SED varies according to the galaxy star forming activity. For active nuclei, the peak is located near the 12 CO(6−5) or 12 CO(7−6) rotational lines, while, for normal nuclei, most of the energy is carried by the 12 CO(4−3) and 12 CO(5−4) lines. Whatever the spectral type of the nucleus, the observed C cooling rate is lower than the observed CO cooling rate (by a factor of 4). The CO cooling curve of nearby starburst galaxies (e.g. NGC 253) has a quite similar shape to the CO cooling curve of distant galaxies. Therefore, the CO cooling curves are useful diagnostics for the star forming activity in distant objects.

show abstract

CI and CO in the spiral galaxies NGC 6946 and M 83

Cited by 85 publications

References 44 publications

Neutral atomic carbon in centers of galaxies

Neutral atomic carbon in centers of galaxies

On the nature of faint mid-infrared sources in M 33

A survey of submillimeter C and CO lines in nearby galaxies

Contact Info

Product

Resources

About