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arXiv 1503.01128astro-ph.GAastro-ph.CO
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z=0.2以下H-ATLAS/GAMA星系[ CII ]/ IR比值的多波长探测

A multi-wavelength exploration of the [CII]/IR ratio in H-ATLAS/GAMA galaxies out to z=0.2

E. Ibar, M. A. Lara-López, R. Herrera-Camus, R. Hopwood, A. Bauer, R. J. Ivison, M. J. Michałowski, H. Dannerbauer, P. van der Werf, D. Riechers, N. Bourne, M. … 展开作者

E. Ibar, M. A. Lara-López, R. Herrera-Camus, R. Hopwood, A. Bauer, R. J. Ivison, M. J. Michałowski, H. Dannerbauer, P. van der Werf, D. Riechers, N. Bourne, M. Baes, I. Valtchanov, L. Dunne, A. Verma, S. Brough, A. Cooray, G. De Zotti, S. Dye, S. Eales, C. Furlanetto, S. Maddox, M. Smith, O. Steele, D. Thomas, E. Valiante

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16 pages, 10 figures, 3 tables
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摘要：

本文研究了在H-ATLAS巡天~ 50 ° ^2范围内选取的28个星系样本中观测到的[CII]-157.74 μ m禁戒精细结构线的行为。样本仅限于通量密度高于S_160um> 150 mJy的星系，并且GAMA调查的光谱为0.02<z<0.2。以这条红移线为中心的远红外光谱是用赫歇尔空间天文台上的PACS仪器拍摄的。星系跨度为10<log（L_IR/Lo）<12（其中L_IR=L_IR[8- 1000 μ m]）和7.3<log（L_[CII]/Lo）<9.3，涵盖了各种光学星系形态。在高红外光度下，样品表现出所谓的[CII]亏损，即L_[CII]/L_IR（以下简称[CII]/IR）在高L_IR下减小。特别是高比值的尘埃，其特征为：（1）L_IR<10^11Lo，（2）冷尘埃温度T_d<30 K，（3）r波段影像上的盘状形貌，（4）WISE色0.5<S_12um/S_22um<1.0，（5）S_（12）μ m/S_22um<1.0，（6）S_（12）μ m/S_22um<1.0，（7）S_（12）μ m/S_22um<1.0，（8）S_（12）μ m/S_22um<1.0。（5）低表面亮度Sigma_IR~10^8-9 Lo kpc^-2，（6）比恒星形成速率sSFR~0.05-3 Gyr^-1。我们认为远紫外辐射场的强度<G_O>是控制[CII]/IR比值的主要参数。相对高的温度可能<G_O>会产生带正电的尘埃颗粒分布，阻碍从这些颗粒中有效地光电提取电子，然后碰撞激发碳原子。在较亮的IR星族中，11&lt;log（L_IR/Lo）&lt;12，低的[CII]/IR比不太可能被[CII]自吸收所改变，也不可能被中等亮度的活动星系核（通过BPT图识别）所控制。

英文摘要：

We explore the behaviour of [CII]-157.74um forbidden fine-structure line observed in a sample of 28 galaxies selected from ~50deg^2 of the H-ATLAS survey. The sample is restricted to galaxies with flux densities higher than S_160um>150mJy and optical spectra from the GAMA survey at 0.02<z<0.2. Far-IR spectra centred on this redshifted line were taken with the PACS instrument on-board the Herschel Space Observatory. The galaxies span 10<log(L_IR/Lo)<12 (where L_IR=L_IR[8-1000um]) and 7.3<log(L_[CII]/Lo)<9.3, covering a variety of optical galaxy morphologies. The sample exhibits the so-called [CII] deficit at high IR luminosities, i.e. L_[CII]/L_IR (hereafter [CII]/IR) decreases at high L_IR. We find significant differences between those galaxies presenting [CII]/IR>2.5x10^-3 with respect to those showing lower ratios. In particular, those with high ratios tend to have: (1) L_IR<10^11Lo; (2) cold dust temperatures, T_d<30K; (3) disk-like morphologies in r-band images; (4) a WISE colour 0.5<S_12um/S_22um<1.0; (5) low surface brightness Sigma_IR~10^8-9 Lo 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 [CII]/IR ratio. It is possible that relatively high <G_O> creates a positively charged dust grain distribution, impeding an efficient photo-electric extraction of electrons from these grains to then collisionally excite carbon atoms. Within the brighter IR population, 11<log(L_IR/Lo)<12, the low [CII]/IR ratio is unlikely to be modified by [CII] self absorption or controlled by the presence of a moderately luminous AGN (identified via the BPT diagram).

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