The radio continuum structure of the edge-on spiral galaxy NGC 4945

Elmouttie, Marc; Haynes, R. F.; Jones, K. L.; Ehle, M.; Beck, Rainer; Harnett, Joanna; Wielebinski, R.

doi:10.1093/mnras/284.4.830

Cited by 30 publications

(26 citation statements)

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“…Both galaxies are edge-on spirals, and the elongation axes of the submillimeter continua are aligned with the large-scale optical major axes (Gardner et al 1992;Elmouttie et al 1997). The continuum in NGC 4945 is also resolved along the minor axis, spanning  » 1.…”

Section: Continuum Emissionmentioning

confidence: 99%

SUBMILLIMETER H₂O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

Pesce

Braatz

Impellizzeri

2016

ApJ

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We present 321 GHz observations of five active galactic nuclei (AGNs) from ALMA Cycle 0 archival data: NGC 5793, NGC 1068, NGC 1386, NGC 4945, and the Circinus galaxy. Submillimeter maser emission is detected for the first time toward NGC 4945, and we present a new analysis of the submillimeter maser system in Circinus. None of the other three galaxies show maser emission, although we have detected and imaged the continuum from every galaxy. Both NGC 4945 and Circinus are known to host strong (10 Jy) 22 GHz megamaser emission, and VLBI observations have shown that the masers reside in the innermost ∼1 pc of the galaxies. The peak flux densities of the 321 GHz masers in both systems are substantially weaker (by a factor of ∼100) than what is observed at 22 GHz, although the corresponding isotropic luminosities are more closely matched (within a factor of ∼10) between the two transitions. We compare the submillimeter spectra presented here to the known 22 GHz spectra in both galaxies, and we argue that while both transitions originate from the gaseous environment near the AGNs, not all sites are in common. In Circinus, the spectral structure of the 321 GHz masers indicates that they may trace the accretion disk at radii interior to the 22 GHz masers. The continuum emission in NGC 4945 and NGC 5793 shows a spatial distribution indicative of an origin in the galactic disks (likely thermal dust emission), while for the other three galaxies the emission is centrally concentrated and likely originates from the nucleus.

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Section: Continuum Emissionmentioning

confidence: 99%

SUBMILLIMETER H₂O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

Pesce

Braatz

Impellizzeri

2016

ApJ

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“…Harnett et al (1989) found that the radio emission has a strong central contribution with emission extended 10 arcmin perpendicular to the major axis. Multi-frequency observations have been carried out by Elmouttie et al (1997). They focused on the large scale structure using a beam size of ∼ 25 ′′ , and found that the spectral index steepens from the central region to the main disk of the galaxy.…”

Section: Individual Galaxiesmentioning

confidence: 99%

Star formation in southern Seyfert galaxies

Forbes¹,

Norris²

1998

Monthly Notices RAS

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We have produced radio maps, using the ATCA, of the central regions of six southern Seyfert 2 galaxies (NGC 1365, 4945, 6221, 6810, 7582, and Circinus) with circumnuclear star formation, to estimate the relative contribution of star formation activity compared to activity from the active galactic nucleus (AGN). The radio morphologies range from extended diffuse structures to compact nuclear emission, with no evidence, even in the relatively compact sources, for synchrotron self-absorption. In each case the radio to far-infrared (FIR) ratio has a value consistent with star formation, and in all but one case the radio to [FeII] ratio is also consistent with star formation. We derive supernova rates and conclude that, despite the presence of a Seyfert nucleus in these galaxies, the radio, FIR, and [FeII] line emission are dominated by processes associated with the circumnuclear star formation (i.e. supernova remnants and H II regions) rather than with the AGN.

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“…The nucleus is well-defined at radio frequencies (S 1.4GHz = 4.9 Jy; Elmouttie et al 1997) and shows little ultra compact structure on a milliarcsec scale (Preston et al 1985;Sadler et al 1995). Microwave transitions of molecules have been detected in dense clouds that envelope the nucleus; this includes the first discovered "megamaser" (Dos Santos & Lépine 1979;Batchelor et al 1982;Whiteoak & Gardner 1986), a possible circumnuclear disk of radius 0.3 pc with a binding mass of ∼10 6 M (Greenhill et al 1997), and numerous transitions at cm and mm wavelengths (see e.g.…”

Section: Introductionmentioning

confidence: 99%

“…References: 1) Whiteoak & Bunton (1985) 5) 2) Elmouttie et al (1997) 6) Ables et al (1987) 3) Whiteoak & Gardner (1977) 7) Dahlem et al (1993) 4) de Vaucouleurs et al (1991) Bergman et al 1992;Dahlem et al 1993). Properties of NGC 4945 relevant to this paper are summarized in Table 1.…”

Section: Introductionmentioning

confidence: 99%

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Atomic and molecular gas in the starburst galaxy NGC 4945

Ott

Whiteoak

Henkel

et al. 2001

A&A

Self Cite

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Abstract. Spatial and kinematical correlations between the H i and12 CO(2−1) emission of the southern spiral galaxy NGC 4945 are studied with a common angular resolution of ∼23 (corresponding to 750 pc at D = 6.7 Mpc) and a velocity resolution of ∼7 km s −1 . The 1.4 GHz continuum emission is also observed. The H i kinematics yield a galaxy mass of ∼1.4×1011 M within radius R = 380 , with molecular and neutral atomic gas each contributing ∼2%, respectively. A central continuum source of size 7 . 6 × 3 . 4 (250 × 110 pc) is enveloped by a molecular cloud of mass 1.5 × 10 9 M for R ≤ 7 . 5, and is rapidly rotating with Vrot ∼ 160 km s −1 . H i emission from the central region at velocities |V −Vsys| > 200 km s −1 may be related to optically detected gas that is believed to trace an outflow directed towards the halo. Nuclear H i absorption at V -Vsys ∼ +80 km s −1 suggests inflow towards the centre, that was so far only seen in molecular lines. H i features at each end of the major axis (|R| ∼ 600 ) are interpreted as spiral arms that are viewed tangentially and that also cause prominent emission features in the radio continuum, H i, and CO further inside the galaxy. A central elongated region showing non-circular motions is interpreted as a bar which fuels the nuclear starburst. The H i and CO position-velocity data have been analysed using linear resonance theory, and possible locations of resonances are identified.

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The radio continuum structure of the edge-on spiral galaxy NGC 4945

Cited by 30 publications

References 0 publications

SUBMILLIMETER H₂O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

SUBMILLIMETER H₂O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

Star formation in southern Seyfert galaxies

Atomic and molecular gas in the starburst galaxy NGC 4945

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The radio continuum structure of the edge-on spiral galaxy NGC 4945

Cited by 30 publications

References 0 publications

SUBMILLIMETER H2O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

SUBMILLIMETER H2O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

Star formation in southern Seyfert galaxies

Atomic and molecular gas in the starburst galaxy NGC 4945

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Product

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SUBMILLIMETER H₂O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY

SUBMILLIMETER H₂O MEGAMASERS IN NGC 4945 AND THE CIRCINUS GALAXY