Mid‐Infrared Diagnostics of Starburst Galaxies: Clumpy, Dense Structures in Star‐Forming Regions in the Antennae (NGC 4038/4039)

Snijders, L.; Kewley, Lisa J.; Werf, P. P. van der

doi:10.1086/521522

Cited by 50 publications

(86 citation statements)

References 56 publications

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“…5. the metallicity, the higher the age of the stellar population, and the higher the gas density, the lower should be the II] 12.81 line ratios are also lower in the center than around it. This ratio ranges between 0.002 and 0.013 in the center, which indicate densities larger than 10 6 cm −3 in a >5 Myr old starburst system with solar metallicity and relatively high (q = 8 × 10 8 ) ionization parameter (Snijders et al 2007, their 2)) are about ten times higher than the observed ratios. These can be a consequence of the about ten times higher extinction found in NGC 4945 than in the sample of galaxies used by PereiraSantaella et al (2010).…”

Section: Discussionmentioning

confidence: 66%

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The deeply obscured AGN of NGC 4945

Pérez-Beaupuits

Spoon

Spaans

et al. 2011

A&A

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Context. The nearly edge-on galaxy NGC 4945 is one of the closest galaxies where an AGN and starburst coexist, and is one of the brightest sources at 100 keV. Near and mid-infrared spectroscopy have shown very strong obscuration of its central region, rivaled only in strength by some of the most deeply obscured ULIRGs. In addition, we mapped the S(1), S(2), and S(3) pure rotational lines of H 2 , which trace the distribution of warm molecular hydrogen. Finally, we obtained an extinction map (A V ) based on the apparent strength of the 9.7 μm silicate absorption feature. Results. At a spatial resolution of ∼5 , our extinction map traces the contours of the starburst ring. The highest extinction is, however, found at the nucleus, where we measure A V (9.85 μm) ≈ 60. Within the uncertainty of the astrometry, all emission lines are found to peak on the nucleus, except for the warm molecular hydrogen emission, which shows a maximum 60−100 pc NW of the nucleus. We favor a scenario in which the emission of the lower H 2 0−0 S(1) and S(2) rotational lines originate mainly in an unobscured extranuclear component associated with the super-wind cone observed in the HST NICMOS map of the H 2 1−0 S (1)

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Section: Discussionmentioning

confidence: 66%

“…5), with the exception of NGC 7130, the only galaxy classified as LINER/Seyfert 2 in their sample. According to (Snijders et al 2007), the higher Fig. 11.…”

Section: Discussionmentioning

confidence: 97%

The deeply obscured AGN of NGC 4945

Pérez-Beaupuits

Spoon

Spaans

et al. 2011

A&A

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“…Rigby et al 2011, and references therein). Snijders et al (2007) shows that a geometrical model in which several individual starforming clumps are embedded in a giant molecular cloud can reproduce these extreme ISM conditions. We speculate that global spectra of our high redshift galaxies may be dominated by H II regions similar to the clumpy, dense star-forming regions in the Antennae and M82.…”

Section: Testing the Cosmic Bpt Diagrammentioning

confidence: 97%

The Cosmic BPT Diagram: Confronting Theory With Observations

Kewley

Maier

Yabe

et al. 2013

ApJ

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240

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We compare a large sample of galaxies between 0.5 < z < 2.6 with theoretical predictions for how the optical diagnostic line ratios in galaxy ensembles change as a function of cosmic time. We show that star forming galaxies at high redshift (z > 1.5) are consistent with a model in which the ISM conditions are more extreme at high redshift than seen in the global spectra of local galaxies. We speculate that global spectra of our high redshift galaxies may be dominated by H II regions similar to the extreme clumpy, dense star-forming complexes in the Antennae and M82. The transition to local-type conditions occurs between 0.8 < z < 1.5. We conclude that classification schemes developed for local samples should not be applied at high redshift (z ≥ 1.5). We use our theoretical models to derive a new redshift-dependent classification line that utilizes the standard optical diagnostic line ratios [O III]/Hβ and [N II]/Hα. Our new line can be used to separate star-forming galaxies from AGN between z = 0 to z ∼ 3.5. We anticipate that our redshift-dependent optical classification line will be useful for future large surveys with near-infrared multi-object spectrographs. We apply our classification line to a sample of gravitationally lensed galaxies at z ∼ 2.5. Although limited by small numbers, we show that our classification line is consistent with the position of AGN that have been independently confirmed via other methods.

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“…More problematic is the fact that the models do not give a very good description of the observed spectrum of H ii regions. Snijders et al (2007) compared the MAPPINGS models with the observations of Giveon et al (2002) Giveon et al (2002) data. Here, the grids are shown only for κ = ∞-the grids for κ = 20 fully overlap these grids.…”

Section: The Ir Linesmentioning

confidence: 99%

NEW STRONG-LINE ABUNDANCE DIAGNOSTICS FOR H II REGIONS: EFFECTS OF Κ-Distributed ELECTRON ENERGIES AND NEW ATOMIC DATA

Dopita

Sutherland

Nicholls

et al. 2013

ApJS

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297

466

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Recently, Nicholls et al., inspired by in situ observations of solar system astrophysical plasmas, suggested that the electrons in H ii regions are characterized by a κ-distribution of energies rather than a simple Maxwell-Boltzmann distribution. Here, we have collected together new atomic data within a modified photoionization code to explore the effects of both the new atomic data and the κ-distribution on the strong-line techniques used to determine chemical abundances in H ii regions. By comparing the recombination temperatures (T rec ) with the forbidden line temperatures (T FL ), we conclude that κ ∼ 20. While representing only a mild deviation from equilibrium, this result is sufficient to strongly influence abundances determined using methods that depend on measurements of the electron temperature from forbidden lines. We present a number of new emission line ratio diagnostics that cleanly separate the two parameters determining the optical spectrum of H ii regions-the ionization parameter q or U and the chemical abundance, 12+log(O/H). An automated code to extract these parameters is presented. Using the homogeneous data set from van Zee et al., we find self-consistent results between all of these different diagnostics. The systematic errors between different line ratio diagnostics are much smaller than those found in the earlier strong-line work. Overall, the effect of the κ-distribution on the strong-line abundances derived solely on the basis of theoretical models is rather small.

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Mid‐Infrared Diagnostics of Starburst Galaxies: Clumpy, Dense Structures in Star‐Forming Regions in the Antennae (NGC 4038/4039)

Cited by 50 publications

References 56 publications

The deeply obscured AGN of NGC 4945

The deeply obscured AGN of NGC 4945

The Cosmic BPT Diagram: Confronting Theory With Observations

NEW STRONG-LINE ABUNDANCE DIAGNOSTICS FOR H II REGIONS: EFFECTS OF Κ-Distributed ELECTRON ENERGIES AND NEW ATOMIC DATA

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