Disentangling the ISM phases of the dwarf galaxy NGC 4214 using [C II] SOFIA/GREAT observations
The [CII] 158 um fine structure line is one of the dominant cooling lines in the interstellar medium (ISM) and is an important tracer of star formation. Recent velocity-resolved studies with Herschel/HIFI and SOFIA/GREAT showed that the [CII] line can constrain the properties of the ISM phases in st...
Gespeichert in:
| Hauptverfasser: | , , , |
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| Dokumenttyp: | Article (Journal) Kapitel/Artikel |
| Sprache: | Englisch |
| Veröffentlicht: |
November 8, 2016
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| In: |
Arxiv
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| Online-Zugang: | Verlag, kostenfrei, Volltext: http://arxiv.org/abs/1611.02039
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| Verfasserangaben: | K. Fahrion, D. Cormier, F. Bigiel, S. Hony, N.P. Abel, P. Cigan, T. Csengeri, U.U. Graf, V. Lebouteiller, S.C. Madden, R. Wu, and L. Young |
| Zusammenfassung: | The [CII] 158 um fine structure line is one of the dominant cooling lines in the interstellar medium (ISM) and is an important tracer of star formation. Recent velocity-resolved studies with Herschel/HIFI and SOFIA/GREAT showed that the [CII] line can constrain the properties of the ISM phases in star-forming regions. The [CII] line as a tracer of star formation is particularly important in low-metallicity environments where CO emission is weak because of the presence of large amounts of CO-dark gas. The nearby irregular dwarf galaxy NGC 4214 offers an excellent opportunity to study an actively star-forming ISM at low metallicity. We analyzed the spectrally resolved [CII] line profiles in three distinct regions at different evolutionary stages of NGC 4214 with respect to ancillary HI and CO data in order to study the origin of the [CII] line. We used SOFIA/GREAT [CII] 158 um observations, HI data from THINGS, and CO(2-1) data from HERACLES to decompose the spectrally resolved [CII] line profiles into components associated with neutral atomic and molecular gas. We use this decomposition to infer gas masses traced by [CII] under different ISM conditions. Averaged over all regions, we associate about 46% of the [CII] emission with the HI emission. However, we can assign only around 9% of the total [CII] emission to the cold neutral medium (CNM). We found that about 79% of the total molecular hydrogen mass is not traced by CO emission. On average, the fraction of CO-dark gas dominates the molecular gas mass budget. The fraction seems to depend on the evolutionary stage of the regions: it is highest in the region covering a super star cluster in NGC 4214, while it is lower in a more compact, more metal-rich region. |
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| Beschreibung: | Gesehen am 25.10.2017 |
| Beschreibung: | Online Resource |