Universität zu Köln

Fahrion, K., Cormier, D., Bigiel, F., Hony, S., Abel, N. P., Cigan, P., Csengeri, T., Graf, U. U., Lebouteiller, V., Madden, S. C., Wu, R. and Young, L. (2017). Disentangling the ISM phases of the dwarf galaxy NGC 4214 using [C II] SOFIA/GREAT observations. Astron. Astrophys., 599. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. The [C II]158 mu m 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 [C II] line can constrain the properties of the ISM phases in star-forming regions. The [C II]ne 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. Aims. 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 [C II] line profiles in three distinct regions at different evolutionary stages of NGC 4214 with respect to ancillary H (I) nd CO data in order to study the origin of the [C II] line. Methods. We used SOFIA/GREAT [C II] 158 mu m observations, H Idata from THINGS, and CO( 2 -> 1) data from HERACLES to decompose the spectrally resolved [C II] line profiles into components associated with neutral atomic and molecular gas. We use this decomposition to infer gas masses traced by [C II] under different ISM conditions. Results. Averaged over all regions, we associate about 46% of the [C II] emission with the H i emission. However, we can assign only similar to 9% of the total [C II] emission to the cold neutral medium (CNM). We found that about 79% of the total molecular hydrogen mass is not traced by CO emission. Conclusions. 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.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Fahrion, K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cormier, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bigiel, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hony, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Abel, N. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cigan, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Csengeri, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Graf, U. U. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lebouteiller, V. UNSPECIFIED UNSPECIFIED UNSPECIFIED Madden, S. C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wu, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Young, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-237912
DOI:	10.1051/0004-6361/201629341
Journal or Publication Title:	Astron. Astrophys.
Volume:	599
Date:	2017
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HUBBLE-SPACE-TELESCOPE; YOUNG STELLAR POPULATION; LOW-METALLICITY GALAXY; STAR-FORMATION; IRREGULAR GALAXIES; INTERSTELLAR-MEDIUM; IONIZED-GAS; CONVERSION FACTOR; MOLECULAR GAS; NGC-4214 Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23791