High-Resolution Mid-Infrared Imaging of Infrared-luminous Galaxies

Miles, John W.; Houck, J. R.; Hayward, T. L.; Ashby, M. L. N.

doi:10.1086/177412

Cited by 41 publications

(49 citation statements)

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“…11, Table 5) dominated by a single core. Previous mid IR maps by Miles et al (1996) have insufficient resolution to resolve the galaxy but their absolute photometry is consistent with ours. The 5 resolution UCL spectrum (Roche et al 1991) is rather featureless, whereas the ISOPHT spectrum contains several PAH bands (Schulz, priv.…”

Section: Ngc 7674supporting

confidence: 85%

Mid–infrared emission of galactic nuclei

Siebenmorgen

Krügel

Spoon³

2004

A&A

139

242

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Abstract.We investigate the mid-infrared radiation of galaxies that are powered by a starburst or by an AGN. For this end, we compare the spectra obtained at different spatial scales in a sample of infrared bright galaxies. ISO observations which include emission of the nucleus as well as most of the host galaxy are compared with TIMMI2 spectra of the nuclear region. We find that ISO spectra are generally dominated by strong PAH bands. However, this is no longer true when inspecting the mid-infrared emission of the pure nucleus. Here PAH emission is detected in starbursts whereas it is significantly reduced or completely absent in AGNs. A physical explanation of these new observational results is presented by examining the temperature fluctuation of a PAH after interaction with a photon. It turns out that the hardness of the radiation field is a key parameter for quantifying the photo-destruction of small grains. Our theoretical study predicts PAH evaporation in soft X-ray environments. Radiative transfer calculations of clumpy starbursts and AGN corroborate the observational fact that PAH emission is connected to starburst activity whereas PAHs are destroyed near an AGN. The radiative transfer models predict for starbursts a much larger mid-infrared size than for AGN. This is confirmed by our TIMMI2 acquisition images: We find that the mid-infrared emission of Seyferts is dominated by a compact core while most of the starbursts are spatially resolved.

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Section: Ngc 7674supporting

confidence: 85%

Mid–infrared emission of galactic nuclei

Siebenmorgen

Krügel

Spoon³

2004

A&A

139

242

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“…VLBI studies did not detect a compact radio core (Hill et al 2001). The 11.7 μm image acquired by Miles et al (1996) provided a similar measurement of the size as the VISIR image (Fig. 2) in the outer parts, but this correlation no longer exists in the central sub-arcsec region.…”

Section: Mkn 617mentioning

confidence: 74%

Nuclear activity in nearby galaxies

Siebenmorgen¹,

Haas

Pantin

et al. 2008

A&A

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Aims. Dust enshrouded activity can be studied ideally by mid-infrared (MIR) observations. To explore the active galactic nuclei (AGN) versus star forming origin of the nuclear MIR emission of galaxies, observations of high spatial resolution are required. We report on 11.3 μm observations with VISIR at the VLT, which reach 0.35 spatial resolution (FWHM). Methods. During the scientific verification of VISIR, we observed a sample of 36 nearby galaxies with a range of optically classified nuclear activity: 17 black hole driven AGN, 10 starbursts (SB), and 9 quiescent spirals. Results. 16 objects out of 17 AGN are detected and unresolved, 5 out of 10 SB are detected and resolved with structured emission up to a few arcsec, while for 5 targets out of 10 SB and all 9 quiet nuclei low upper limits are provided. The morphology of the resolved SB nuclei is similar to that observed at radio frequencies. The compactness of AGN and the extent of SB nuclei is consistent with the predictions of radiative transfer models and Spitzer spectra observed at much lower spatial resolution than with VISIR. We introduce the nuclear MIR surface brightness, S , as a quantitative measurement for AGN and SB activity. Although one is unable to distinguish between AGN and SB activity using the nuclear MIR surface brightness derived from 4 m class telescopes, our data indicate that, out to a distance of 100 Mpc, the MIR surface brightness acquired by 8 m class telescopes can differentiate AGN from SB behavior.

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“…The disks of two galaxies are already coalesced. An early MIR observation of Miles et al (1996) found evidence for a second nucleus about 1. 2 south of the primary nucleus, which might coincide with a weak radio source in the high resolution Very Large Array (VLA) radio continuum map (Condon et al 1991).…”

Section: Comparisons With Previous Resultsmentioning

confidence: 99%

Alma Observations of Warm Molecular Gas and Cold Dust in NGC 34

Cao

et al. 2014

ApJ

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We present Atacama Large Millimeter Array (ALMA) Cycle-0 observations of the CO (6-5) line emission (restframe frequency = 691.473 GHz) and of the 435 μm dust continuum emission in the nuclear region of NGC 34, a local luminous infrared galaxy at a distance of 84 Mpc (1 = 407 pc) which contains a Seyfert 2 active galactic nucleus (AGN) and a nuclear starburst. The CO emission is well resolved by the ALMA beam (0. 26 × 0. 23), with an integrated flux of f CO(6-5) = 1004 (±151) Jy km s −1 . Both the morphology and kinematics of the CO (6-5) emission are rather regular, consistent with a compact rotating disk with a size of 200 pc. A significant emission feature is detected on the redshifted wing of the line profile at the frequency of the H 13 CN (8-7) line, with an integrated flux of 17.7 ± 2.1(random) ± 2.7(systematic) Jy km s −1 . However, it cannot be ruled out that the feature is due to an outflow of warm dense gas with a mean velocity of 400 km s −1 . The continuum is resolved into an elongated configuration, and the observed flux corresponds to a dust mass of M dust = 10 6.97±0.13 M . An unresolved central core (radius 50 pc) contributes 28% of the continuum flux and 19% of the CO (6-5) flux, consistent with insignificant contributions of the AGN to both emissions. Both the CO (6-5) and continuum spatial distributions suggest a very high gas column density ( 10 4 M pc −2 ) in the nuclear region at radius 100 pc.

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High-Resolution Mid-Infrared Imaging of Infrared-luminous Galaxies

Cited by 41 publications

References 0 publications

Mid–infrared emission of galactic nuclei

Mid–infrared emission of galactic nuclei

Nuclear activity in nearby galaxies

Alma Observations of Warm Molecular Gas and Cold Dust in NGC 34

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