Universität zu Köln

Tarantino, Elizabeth ORCID: 0000-0003-1356-1096, Bolatto, Alberto D., Herrera-Camus, Rodrigo, Harris, Andrew, I, Wolfire, Mark, Buchbender, Christof ORCID: 0000-0002-2064-7691, Croxall, Kevin, V, Dale, Daniel A., Groves, Brent, Levy, Rebecca C., Riquelme, Denise, Smith, J-D T. and Stutzki, Juergen (2021). Characterizing the Multiphase Origin of [CII] Emission in M101 and NGC 6946 with Velocity-resolved Spectroscopy. Astrophys. J., 915 (2). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

The [C II] fine-structure transition at 158 mu m is frequently the brightest far-infrared line in galaxies. Due to its low ionization potential, C+ can trace the ionized, atomic, and molecular phases of the ISM. We present velocity-resolved [C II] and [N II] pointed observations from SOFIA/GREAT on similar to 500 pc scales in the nearby galaxies M101 and NGC 6946 and investigate the multiphase origin of [C II] emission over a range of environments. We show that ionized gas makes a negligible contribution to the [C II] emission in these positions using [N II] observations. We spectrally decompose the [C II] emission into components associated with the molecular and atomic phases using existing CO (2-1) and H I data and show that a peak signal-to-noise ratio of 10-15 is necessary for a reliable decomposition. In general, we find that in our pointings greater than or similar to 50% of the [C II] emission arises from the atomic phase, with no strong dependence on star formation rate, metallicity, or galactocentric radius. We do find a difference between pointings in these two galaxies, where locations in NGC 6946 tend to have larger fractions of [C II] emission associated with the molecular phase than in M101. We also find a weak but consistent trend for fainter [C II] emission to exhibit a larger contribution from the atomic medium. We compute the thermal pressure of the cold neutral medium through the [C II] cooling function and find log (P-th/k) = 3.8-4.6 [K cm(-3)], a value slightly higher than similar determinations, likely because our observations are biased toward star-forming regions.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Tarantino, Elizabeth UNSPECIFIED orcid.org/0000-0003-1356-1096 UNSPECIFIED Bolatto, Alberto D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Herrera-Camus, Rodrigo UNSPECIFIED UNSPECIFIED UNSPECIFIED Harris, Andrew, I UNSPECIFIED UNSPECIFIED UNSPECIFIED Wolfire, Mark UNSPECIFIED UNSPECIFIED UNSPECIFIED Buchbender, Christof UNSPECIFIED orcid.org/0000-0002-2064-7691 UNSPECIFIED Croxall, Kevin, V UNSPECIFIED UNSPECIFIED UNSPECIFIED Dale, Daniel A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Groves, Brent UNSPECIFIED UNSPECIFIED UNSPECIFIED Levy, Rebecca C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Riquelme, Denise UNSPECIFIED UNSPECIFIED UNSPECIFIED Smith, J-D T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Stutzki, Juergen UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-597618
DOI:	10.3847/1538-4357/abfcc6
Journal or Publication Title:	Astrophys. J.
Volume:	915
Number:	2
Date:	2021
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language C-II EMISSION; 158 MU-M; NEARBY SPIRAL GALAXIES; NEUTRAL ATOMIC PHASES; STAR-FORMATION RATES; MOLECULAR GAS; H-ALPHA; PHOTODISSOCIATION REGIONS; INTERSTELLAR-MEDIUM; INFRARED-EMISSION Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59761