A multiwavelength exploration of the [C II]/IR ratio in H-ATLAS/GAMA galaxies out to z = 0.2

Autor(en): E. Ibar, M. A. Lara-Lopez, R. Herrera-Camus, Rosalind Hopwood, A. Bauer, Helmut Dannerbauer
Abstrakt: We explore the behaviour of [C II] λ157.74 μm forbidden fine-structure line observed in a sample of 28 galaxies selected from ~ 50 deg2 of the Herschel-Astrophysical Terahertz Large Area Survey survey. The sample is restricted to galaxies with flux densities higher than S₁₆₀ _μm > 150 mJy and optical spectra from the Galaxy and Mass Assembly survey at 0.02 < z < 0.2. Far-IR spectra centred on this redshifted line were taken with the Photodetector Array Camera and Spectrometer instrument on-board the Herschel Space Observatory. The galaxies span 10 < log(L_IR/L_⊙) < 12 (where L_IR ≡ L_IR[8-1000 μm]) and 7.32.5 × 10^-3 with respect to those showing lower ratios. In particular, those with high ratios tend to have: (1) LIR < 10¹¹ L_⊙; (2) cold dust temperatures, Td < 30 K; (3) disc-like morphologies in r-band images; (4) a Wide-field Infrared Survey Explorer colour 0.5 ≲ S_{12 μm}/S_{22 μm} ≲ 1.0; (5) low surface brightness Σ_IR ≈ 10^8-9 L_⊙ kpc^-2, (6) and specific star formation rates of sSFR ≈ 0.05-3 Gyr^-1. We suggest that the strength of the far-UV radiation fields (<G_O>) is main parameter responsible for controlling the [C II]/IR ratio. It is possible that relatively high (<G_O>) creates a positively charged dust grain distribution, impeding an efficient photoelectric extraction of electrons from these grains to then collisionally excite carbon atoms. Within the brighter IR population, 11 < log(L_IR/L_⊙) < 12, the low [C II]/IR ratio is unlikely to be modified by [C II] self-absorption or controlled by the presence of a moderately luminous AGN (identified via the BPT diagram).
Organisation(en): Institut für Astrophysik
Externe Organisation(en): Universidad de Valparaíso, Universidad Nacional Autonoma de Mexico, Australian Astronomical Observatory, University of Maryland, College Park, Imperial College London
Journal: Monthly Notices of the Royal Astronomical Society
Band: 449
Seiten: 2498 - 2513
Anzahl der Seiten: 16
ISSN: 0035-8711
Publikationsdatum: 05-2015
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/95fb99e1-45ed-44f9-9ff0-d88a28423a23

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