Skip to main content

Research Repository

Advanced Search

Strong Far-ultraviolet Fields Drive the [C ii]/Far-infrared Deficit in z ∼ 3 Dusty, Star-forming Galaxies

Rybak, Matus; Rivera, G. Calistro; Hodge, J.A.; Smail, Ian; Walter, F.; van der Werf, P.; da Cunha, E.; Chen, Chian-Chou; Dannerbauer, H.; Ivison, R.J.; Karim, A.; Simpson, J.M.; Swinbank, A.M.; Wardlow, J.L.

Strong Far-ultraviolet Fields Drive the [C ii]/Far-infrared Deficit in z ∼ 3 Dusty, Star-forming Galaxies Thumbnail


Authors

Matus Rybak

G. Calistro Rivera

J.A. Hodge

F. Walter

P. van der Werf

E. da Cunha

Chian-Chou Chen

H. Dannerbauer

R.J. Ivison

A. Karim

J.M. Simpson

J.L. Wardlow



Abstract

We present 0farcs15 (1 kpc) resolution ALMA observations of the [C ii] 157.74 μm line and rest-frame 160 μm continuum emission in two z ~ 3 dusty, star-forming galaxies—ALESS 49.1 and ALESS 57.1, combined with resolved CO (3–2) observations. In both sources, the [C ii] surface brightness distribution is dominated by a compact core ≤1 kpc in radius, a factor of 2–3 smaller than the extent of the CO (3–2) emission. In ALESS 49.1, we find an additional extended (8 kpc radius), low surface brightness [C ii] component. Based on an analysis of mock ALMA observations, the [C ii] and 160 μm continuum surface brightness distributions are inconsistent with a single-Gaussian surface brightness distribution with the same size as the CO (3–2) emission. The [C ii] rotation curves flatten at sime2 kpc radius, suggesting that the kinematics of the central regions are dominated by a baryonic disk. Both galaxies exhibit a strong [C ii]/far-IR (FIR) deficit on 1 kpc scales, with FIR surface brightness to [C ii]/FIR slope steeper than in local star-forming galaxies. A comparison of the [C ii]/CO (3–2) observations with photodissociation region models suggests a strong far-UV (FUV) radiation field (G 0 ~ 104) and high gas density (n(H) ~ 104–105 cm−3) in the central regions of ALESS 49.1 and ALESS 57.1. The most direct interpretation of the pronounced [C ii]/FIR deficit is a thermal saturation of the C+ fine-structure levels at temperatures ≥500 K, driven by the strong FUV field.

Citation

Rybak, M., Rivera, G. C., Hodge, J., Smail, I., Walter, F., van der Werf, P., …Wardlow, J. (2019). Strong Far-ultraviolet Fields Drive the [C ii]/Far-infrared Deficit in z ∼ 3 Dusty, Star-forming Galaxies. Astrophysical Journal, 876(2), Article 112. https://doi.org/10.3847/1538-4357/ab0e0f

Journal Article Type Article
Acceptance Date Mar 5, 2019
Online Publication Date May 8, 2019
Publication Date May 10, 2019
Deposit Date May 29, 2019
Publicly Available Date May 30, 2019
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 876
Issue 2
Article Number 112
DOI https://doi.org/10.3847/1538-4357/ab0e0f

Files

Published Journal Article (2.8 Mb)
PDF

Copyright Statement
© 2019. The American Astronomical Society. All rights reserved.






You might also like



Downloadable Citations