CO <i>J</i> = 3-2 mapping of the molecular circumnuclear  disk in Centaurus A

Liszt, H. S.

doi:10.1051/0004-6361:20010443

Cited by 18 publications

(32 citation statements)

References 21 publications

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“…4), indicating the presence of background radio continuum extended in that direction. There is a close correspondence between this absorption and the CO emission as detected by Liszt (2001) (see Fig. 4).…”

Section: H I In Absorptionsupporting

confidence: 77%

Centaurus A: morphology and kinematics of the atomic hydrogen

Struve

Oosterloo

Morganti

et al. 2010

A&A

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We present new ATCA 21-cm line observations of the neutral hydrogen in the nearby radio galaxy Centaurus A. We image in detail (with a resolution down to 7 , ∼100 pc) the distribution of H i along the dust lane. Our data have better velocity resolution and better sensitivity than previous observations. The H i extends for a total of ∼15 kpc. The data, combined with a titled-ring model of the disk, allow to conclude that the kinematics of the H i is that of a regularly rotating, highly warped structure down to the nuclear scale.The parameters (in particular the inclination) of our model are somewhat different from some of the previously proposed models but consistent with what was recently derived from stellar light in a central ring. The model nicely describes also the morphology of the dust lane as observed with Spitzer. There are no indications that large-scale anomalies in the kinematics exist that could be related to supplying material for the AGN. Large-scale radial motions do exist, but these are only present at larger radii (r > 6 kpc). This unsettled gas is mainly part of a tail/arm like structure. The relatively regular kinematics of the gas in this structure suggests that it is in the process of settling down into the main disk. The presence of this structure further supports the merger/interaction origin of the H i in Cen A. From the structure and kinematics we estimate a timescale of 1.6−3.2 × 10 8 yr since the merging event. No bar structure is needed to describe the kinematics of the H i. The comparison of the timescale derived from the large-scale H i structure and those of the radio structure together with the relative regularity of the H i down to the sub-kpc regions does not suggest a oneto-one correspondence between the merger and the phase of radio activity. Interestingly, the radial motions of the outer regions are such that the projected velocities are redshifted compared to the regular orbits. This means that the blueshifted absorption discovered earlier and discussed in our previous paper cannot be caused by out-moving gas at large radius projected onto the centre. Therefore, the interpretation of the blueshifted absorption, together with at least a fraction of the redshifted nuclear absorption, as evidence for a regular inner disk, still holds. Finally, we also report the discovery of two unresolved clouds detected at 5.2 and 11 kpc away (in projection) from the H i disk. They are likely an other example of a left-over of the merger that brought the H i gas.

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Section: H I In Absorptionsupporting

confidence: 77%

Centaurus A: morphology and kinematics of the atomic hydrogen

Struve

Oosterloo

Morganti

et al. 2010

A&A

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“…With these new results, the kinematics of the H I in the inner regions of Cen A appears very similar to that observed in emission for the molecular circumnuclear disk. In particular, Figure 9 shows how the H I absorption compares with the CO disk observed by Liszt (2001). It is important to note that the modelling of the large-scale H I has ruled out that the absorption is due to gas at large distances projected against the centre (Struve et al 2010b).…”

Section: The Sub-kpc Regionmentioning

confidence: 98%

The Many Faces of the Gas in Centaurus A (NGC 5128)

Morganti¹

2010

Publ. – Astron. Soc. Aust

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Centaurus A (NGC 5128) is ideal for investigating the characteristics and role of gas in an earlytype galaxy in the presence of a radio-loud active nucleus. The different phases of the gas -hot (X-ray), warm (ionized), and cold (H I and molecular) -are all detected in this object and can be studied at very high spatial resolution, due to its proximity. This richness makes Centaurus A truly unique. Spatially, these gas structures span from the pc to the tens of kpc scale. Thus, they allow us to trace very different phenomena, from the formation and evolution of the host galaxy, to the interplay between nuclear activity and interstellar medium and the feeding mechanism of the central black hole. A lot of work has been done to study and understand the characteristics of the gas in this complex object, and the present paper summarizes what has been achieved so far.

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“…The differences between CO and Hα in the nucleus of Cen A stand in sharp contrast to what is seen over the larger dust lane, where they behave essentially identically within the various limitations of the observational data. However, the circumnuclear disk in Cen A is well-described as purely rotating (Liszt 2001), which cannot account for the redshifted absorption features. Fig.…”

Section: Kinematicsmentioning

confidence: 99%

“…Until recently it appeared that H I absorption was considerably less extended in velocity, but the broad, faint wing above 600 km s −1 discovered by Sarma et al (2002) corrects this misimpression. Despite its substantial width, all of the absorption toward Cen A is much narrower than even the redshifted portion of the CO emission profile, which represents contributions from both the dust lane and inner circumnuclear disk (Liszt 2001). 3.3. OH and HCO + in NGC 1052, Cen A and the Milky Way Figure 3 shows the HCO + and OH optical depths which have been observed in NGC 1052 and Cen A, along with the sample of local diffuse clouds of and Lucas & Liszt (2000b).…”

Section: Kinematicsmentioning

confidence: 99%

Mm-wave HCO⁺, HCN and CO absorption toward NGC 1052

Liszt¹,

Lucas

2004

A&A

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Abstract. We used the Plateau de Bure Interferometer to observe λ3 mm J = 1−0 absorption lines of HCO + , HCN and CO toward the core of the nearby elliptical, megamaser-host galaxy NGC 1052. The lines are relatively weak, with peak optical depths 0.03 for HCO + and HCN and 0.1 for CO. Nonetheless the inferred column density of molecular gas 2N(H 2 ) 5 × 10 21 cm −2 is consistent with the degree of reddening inferred toward the nucleus from observations of the Balmer series of hydrogen. Mm-wave absorption line profiles are somewhat broader than those of H I and OH, perhaps because lower free-free opacity at mm-wavelengths exposes higher-velocity material nearer the nucleus. Overall, the OH/HCO + ratio in NGC 1052 is as expected from the strong relationship established in local diffuse clouds but the optical depth ratio varies strongly over the line profiles. Similar variations are also seen toward Cen A, which has very different line ratios among H I, OH and HCO + for very nearly the same amount of OH absorption.

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CO J = 3-2 mapping of the molecular circumnuclear disk in Centaurus A

Cited by 18 publications

References 21 publications

Centaurus A: morphology and kinematics of the atomic hydrogen

Centaurus A: morphology and kinematics of the atomic hydrogen

The Many Faces of the Gas in Centaurus A (NGC 5128)

Mm-wave HCO⁺, HCN and CO absorption toward NGC 1052

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CO J = 3-2 mapping of the molecular circumnuclear disk in Centaurus A

Cited by 18 publications

References 21 publications

Centaurus A: morphology and kinematics of the atomic hydrogen

Centaurus A: morphology and kinematics of the atomic hydrogen

The Many Faces of the Gas in Centaurus A (NGC 5128)

Mm-wave HCO+, HCN and CO absorption toward NGC 1052

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Mm-wave HCO⁺, HCN and CO absorption toward NGC 1052