The true nucleus of NGC 253 revealed by high-resolution near-infrared imaging

Sams, B.; Genzel, R.; Eckart, A.; Tacconi-Garman, L. E.; Hofmann, R.

doi:10.1086/187431

Cited by 34 publications

(49 citation statements)

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“…In both of these figures the left panel is the 3.21 µm continuum emission while the right panel shows the continuum-subtracted 3.28 µm PAH feature emission. The continuum in both cases agrees very well with the continuum observed in the K-band (NGC 253: Sams et al 1994;NGC 1808: TGSE96) suggesting that a large fraction of the continuum emission is due to starlight.…”

Section: General Remarkssupporting

confidence: 71%

“…In that work it is demonstrated that a number of discrete sources observed at wavelengths from the optical to the millimetre lie in an elliptical ring of radius ∼50 pc. The dominant feature in images at wavelengths from 1.6 µm to 20 µm (Sams et al 1994;Kalas & Wynn-Williams 1994;Keto et al 1999;Forbes et al 2000;A. Gilbert, private communication) lies in that ring.…”

Section: The Targetsmentioning

confidence: 98%

“…In the bottom panel we show the feature-to-continuum ratio over the same area of NGC 253; the wedge to the right indicates feature-to-continuum values. Contours of the K-band flux (Sams et al 1994, with the peak position shifted to agree with that of Forbes et al 2000) are shown at 6, 9, 14, 21, 33, and 50% of the peak K-band flux. The thin square represents the field-of-view of those K-band observations.…”

Section: Pah Emission On Scales Of the Super Star Clustersmentioning

confidence: 99%

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PAH emission variations within the resolved starbursts of NGC 253 and NGC 1808

Tacconi-Garman¹,

Sturm

Lehnert

et al. 2005

A&A

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Abstract. In order to better characterise the usefulness of PAH emission as a tracer of star formation, we have undertaken a programme of 3 µm narrowband imaging of a sample of nearby template galaxies covering a wide range of metallicity, star formation activity, and nuclear activity. In the present paper we present first results of this programme: high spatial resolution images of PAH feature emission and the adjacent continuum emission from the central regions of the nearby starburst galaxies NGC 253 and NGC 1808, taken with ISAAC at the VLT-UT1. Globally, the feature emission is seen to peak on the central starburst regions of both sources. On smaller scales, however, we see no general spatial correlation or anti-correlation between the PAH feature emission and the location of sites of recent star formation, suggesting that the degree to which PAH feature emission traces starburst activity is more complicated than previously hypothesized based on results from data with lower spatial resolution. We do find spatial correlations, though, when we consider the feature-to-continuum ratio, which is low at the positions of known super star clusters in NGC 1808 as well as at the position of the IR peak in NGC 253. We take this to imply a decrease in the efficiency of PAH emission induced by the star formation, caused either by mechanical energy input into the ISM, photoionisation of the PAH molecules, or photodissociation of the PAH molecules. All three hypotheses are discussed. In addition, for the first time we present observations of PAH feature emission in the superwind of a starbursting system (NGC 253), providing strong support that winds are heavily mass-loaded and entrain substantial amounts of ambient ISM. We have also found a plausible connection between observed NaD absorption, H 2 , and PAHs above the plane of NGC 253. This observation has important implications for enriching galaxy halos and possibly the intergalactic medium with small dust grains.

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Section: General Remarkssupporting

confidence: 71%

Section: The Targetsmentioning

confidence: 98%

Section: Pah Emission On Scales Of the Super Star Clustersmentioning

confidence: 99%

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PAH emission variations within the resolved starbursts of NGC 253 and NGC 1808

Tacconi-Garman¹,

Sturm

Lehnert

et al. 2005

A&A

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“…The most powerful of these radio sources (TH-2) is considered to be the true nucleus of NGC 253, and is thought to be an AGN (Forbes et al 2000). Imaging of NGC 253 has been carried out in the NIR (Forbes et al 1991(Forbes et al , 1993Sams et al 1994;Kalas & Wynn-Williams 1994) and MIR (Pina et al 1992;Keto et al 1993;Böker et al 1998;Keto et al 1999). These observations show that the NIR/MIR emission consists of a bright, barely elongated source plus a secondary, fainter source to the NE of the brightest one.…”

Section: Ngc 253: Mir Detection Of the Radio Nucleus?mentioning

confidence: 99%

Mid-infrared imaging of active galaxies

Galliano¹,

Alloin

Pantin

et al. 2005

A&A

163

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Abstract. High resolution, mid-infrared (MIR) images of nine nearby active galaxies are presented. The data were obtained with the TIMMI 2 instrument mounted at the ESO 3.6 m telescope using a set of N-band narrow filters. The resulting images have an angular resolution of 0.6 −1 . The MIR emission has been resolved in four galaxies: NGC 253, NGC 1365, NGC 1808 and NGC 7469. The images show a circumnuclear population of unknown MIR sources in NGC 1365 and NGC 1808, coincident with radio sources. These MIR/radio sources are interpreted in terms of embedded young star clusters. A high-resolution MIR map of NGC 253 is also presented, and enables the identification of a previously unknown MIR counterpart to the radio nucleus. Extended MIR emission is detected in NGC 7469, and concurs with previous observations in the NIR and radio. For this source, an interesting morphological difference between the 10.4 µm and the 11.9 µm emission is observed, suggesting the presence of a dust-rich micro-bar. Our MIR images of Circinus do not show resolved emission from the nucleus down to an angular scale of 0.5 . In the case of NGC 2992, an upper limit to the extended MIR emission can be set. We provide new MIR flux measurements for the unresolved AGN in NGC 5995, IZw1 and IIZw136.

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“…The latter were able to classify the brighter compact sources as synchrotron or free-free dominated, based on the derived spectral indices. Kalas & Wynn-Williams (1994) and Sams et al (1994) showed that most of the infrared sources are regions of low dust extinction and are not coincident with the radio sources. Hence, the radio sources and the infrared-optical sources seem to trace very different types of objects.…”

Section: Introductionmentioning

confidence: 99%

Multi-density model of the ionised gas in NGC 253 using radio recombination lines

Mohan

Goss²,

Anantharamaiah

2005

A&A

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Abstract.We have imaged the H92α (8.3 GHz), H75α (15 GHz), and H166α (1.4 GHz) Radio Recombination Lines (RRLs) from NGC 253 at resolutions of 4.5 pc (0.4 ) , 2.5 pc (0.2 ) and 53 pc (4.5 ) respectively. The H92α line arises from individual compact sources, most of which possess radio continuum counterparts. The line widths range from ∼200 km s −1 for the sources near the radio nucleus to 70-100 km s −1 for the extranuclear ones. These lines are emitted by gas at a density ∼10 4 cm −3 . The remainder of the cm-wave RRLs arise in lower density gas (∼500 cm −3 ) with a higher area filling factor and with ten times higher mass. A third component of higher density gas (>10 4 cm −3 ) is required to explain the mm-wave RRLs.

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The true nucleus of NGC 253 revealed by high-resolution near-infrared imaging

Cited by 34 publications

References 0 publications

PAH emission variations within the resolved starbursts of NGC 253 and NGC 1808

PAH emission variations within the resolved starbursts of NGC 253 and NGC 1808

Mid-infrared imaging of active galaxies

Multi-density model of the ionised gas in NGC 253 using radio recombination lines

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