[CII] Emission from Low Redshift Analogs of Epoch of Reionization Galaxies

Abstract

We present Herschel/PACS far-infrared spectroscopy of a population of ∼20 local (z<0.2) star-forming galaxies identified in the Sloan Digital Sky Survey and whose specific star-formation rates and extreme emission line properties make them very similar to z>5 Lyman-break galaxies. We detect [CII] emission in about half the sample, with [CII]/L_(IR) ratios which lie between 1.6×10^(–4) and 1.6×10^(–3). We find that [CII]/L_(IR) ratios in mergers are lower by a factor of ∼2–3; however we do not find evidence for a metallicity dependence. We predict based on these measurements that ALMA spectroscopy of z>5 Lyman-break galaxies should reveal median [CII]/L_(IR) ratios of 6×10^(–4) and maybe even as high as 10^(–3), depending on whether mergers or cold gas accretion powers star-formation.

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