Large-scale Hi structure of the Circinus galaxy

Jones, K. L.; Koribalski, B. S.; Elmouttie, Marc; Haynes, R. F.

doi:10.1046/j.1365-8711.1999.02057.x

Cited by 47 publications

(68 citation statements)

References 41 publications

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“…It should be noted that Circinus and NGC 4945 (e.g. Forbes & Norris 1998) are by far the two closest Seyferts, and due to its large extent (Freeman et al 1977;Jones et al 1999) a correction should also be required for Circinus, but this galaxy has not been included in the sample of Rice et al (1988). This may have the effect of maintaining a similar radio/FIR relation between the two galaxies.…”

Section: Elevated (Cf the Ring) Hcn To Co Intensity Ratiomentioning

confidence: 99%

Molecular gas conditions in NGC 4945 and the Circinus galaxy

Curran

Johansson

Bergman

et al. 2001

A&A

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Abstract. We present results of a multi-transition study of the dense molecular gas in the central part of the hybrid star-burst/Seyfert galaxies NGC 4945 and the Circinus galaxy. From the results of radiative transfer calculations, we estimate in NGC 4945 nH 2 = 3 10 3 −10 4 cm −3 and T kin ≈ 100 K and in Circinus nH 2 = 2 10 3 −10 5 cm −3 and T kin ≈ 50−80 K for the molecular hydrogen density and kinetic temperature, respectively. As well as density/temperature tracing molecules, we have observed C17 O and C 18 O in each galaxy and the value of C18 O/C 17 O ≈ 6 for the isotopic column density ratio suggests that both have relatively high populations of massive stars. Finally, although star formation is present, the radiative transfer results combined with the high HCN/CO and (possibly) HCN/FIR, radio/FIR ratios may suggest that, in comparison with Circinus, a higher proportion of the dense gas emission in NGC 4945 may be located in the hypothesised central nuclear disk as opposed to dense star forming cloud cores. Contrary to the literature, which assumes that all of the far-infrared emission arises from star formation, our results suggest that in NGC 4945 some of this emission could arise from an additional source, and so we believe that a revision of the star formation rate estimates may be required for these two galaxies.

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Section: Elevated (Cf the Ring) Hcn To Co Intensity Ratiomentioning

confidence: 99%

Molecular gas conditions in NGC 4945 and the Circinus galaxy

Curran

Johansson

Bergman

et al. 2001

A&A

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“…Carbon monoxide (CO), the second most abundant molecule, has a dipole moment A&A 568, A122 (2014) Maiolino et al 1998;Tully et al 2009). Although it has a large angular size (≥80 ) at optical wavelengths and in atomic gas (Hi), Circinus was not discovered until the 1970s (Freeman et al 1977;Jones et al 1999), because it is located only ∼4 • above the Galactic plane with a Galactic visual extinction of 4.8 mag (e.g., Schlegel et al 1998). H 2 O mega-masers at both mm and submm wavelengths were found in the center of Circinus (e.g., Greenhill et al 2003;Hagiwara et al 2013), indicating a molecular torus around the central SMBH.…”

Section: Introductionmentioning

confidence: 99%

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Zhang

Henkel

Gao

et al. 2014

A&A

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We report mapping observations of the 12 CO J = 3 → 2, 4 → 3, 6 → 5, and 7 → 6 transitions and the C i 3 P 1 → 3 P 0 (C i) 492 GHz transition toward the central 40 ×40 region of the Circinus galaxy, using the Atacama Pathfinder EXperiment (APEX) telescope. We also detected 13 CO J = 3 → 2 at the central position of Circinus. These observations are to date the highest CO transitions reported in Circinus. With large velocity gradient (LVG) modeling and likelihood analysis we try to obtain density, temperature, and column density of the molecular gas in three regions: the nuclear region (D < 18 ∼ 360 pc), the entire central 45 (D < 45 ∼ 900 pc) region, and the star-forming (S-F) ring (18 < D < 45 ). In the nuclear region, we can fit the CO excitation with a single excitation component, yielding an average condition of n H 2 ∼ 10 3.2 cm −3 , T kin ∼ 200 K, and d /dr ∼ 3 km s −1 pc −1 . In the entire 45 region, which covers both the nucleus and the S-F ring, two excitation components are needed with n H 2 ∼ 10 4.2 cm −3 and 10 3.0 cm −3 , T kin ∼ 60 K and 30 K, and M H 2 ∼ 2.3 × 10 7 M and 6.6 × 10 7 M , respectively. The gas excitation in the S-F ring can also be fitted with two LVG components, after subtracting the CO fluxes in the 18 nuclear region. The S-F ring region contributes 80% of the molecular mass in the 45 region. For the entire 45 region, we find a standard conversion factor of N(H 2 )/I CO 1→0 = 0.37 × 10 20 cm −2 (K km s −1 ) −1 , about 1/5 of the Galactic disk value. The luminosity ratios of C i and 12 CO J = 3 → 2 (R CI/CO 3→2 ) in Circinus basically follow a linear trend, similar to that obtained in high-redshift galaxies. The average R CI/CO J = 3 → 2 in Circinus is found to be ∼0.2, lying at an intermediate value between non-AGN nuclear regions and high-redshift galaxies.

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“…1, it does not seem unfeasible that the findings of Charmandaris et al (2000) may be due to a similar situation in Centaurus A 12 : Note that Bryant & Hunstead (1999) obtain the same position angle as for the radio jet axis. In this galaxy, the CO detections also appear to associated with HI clumps (Schiminovich et al 1994) and although in Circinus HI has been detected out to nearly 100 kpc (Jones et al 1999) in a complex spiral/bar structure, it is unclear how this is related to the < ∼ kpc-scale molecular outflow. 10 Pedlar et al (1998) propose a model where the torus is a consequence of the weak radiation emitting from the equator of the continuum source, whereas the cone arises from gas ionised by the strong polar radiation.…”

Section: Discussionmentioning

confidence: 82%

Centaurus A: Molecular gas shells or large-scale outflow?

Curran

2001

A&A

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Abstract. In order to test if the molecular "shells" observed by Charmandaris et al. (2000) could be due to a molecular outflow, we have mapped CO in J = 1 → 0 and 2 → 1 along the jet axis of Centaurus A. Where our map coincides with their observed positions, like them, we obtain 4σ detections with a similar antenna temperature for CO 1 → 0, although both transitions appear to be somewhat wider in velocity dispersion than theirs. As well as these, we have several tentative detections at distances of > ∼ 5 kpc from the nucleus, and although these results are of too poor quality in order to verify or refute the shell model in favour of a molecular outflow, our observations of the inner kpc do suggest that at least a small-scale outflow is a possibility. Whether this would be a component of a larger-scale outflow or exists in conjunction with the molecular gas shells will have to wait for a much more extensive mapping of the large-scale gas distribution in Centaurus A, for which these and the results of Charmandaris et al. (2000) will hopefully provide sufficient motivation.

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Large-scale Hi structure of the Circinus galaxy

Cited by 47 publications

References 41 publications

Molecular gas conditions in NGC 4945 and the Circinus galaxy

Molecular gas conditions in NGC 4945 and the Circinus galaxy

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Centaurus A: Molecular gas shells or large-scale outflow?

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Large-scale Hi structure of the Circinus galaxy

Cited by 47 publications

References 41 publications

Molecular gas conditions in NGC 4945 and the Circinus galaxy

Molecular gas conditions in NGC 4945 and the Circinus galaxy

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci3PP0observations

Centaurus A: Molecular gas shells or large-scale outflow?

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Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations