Far-infrared Properties of Green Pea Galaxies, the Best Local Analogues of Galaxies in the Epoch of Reionization

Speaker

Takuya Hashimoto (University of Tsukuba)

Abstract

I will present a science case proposed by our team using PRIMA/FIRESS: a systematic investigation of the far-infrared properties of Green Pea galaxies, which are among the best local analogues of galaxies in the Epoch of Reionization. ALMA observations have revealed luminous far-infrared fine-structure lines in galaxies out to redshifts of approximately 14. In particular, these galaxies often exhibit [O III] 88 μm emission that is 2-10 times more luminous than [C II] 158 μm. Simulations suggest that such elevated line ratios may reflect highly ionized gas or a low neutral-gas covering fraction, both of which could facilitate the escape of Lyman-continuum photons. However, far-infrared spectroscopy is currently available for only a small number of local Lyman-continuum emitters.

We therefore propose PRIMA/FIRESS observations of Green Pea galaxies. FIRESS can detect multiple diagnostic lines, including [N III] 57 μm, [O I] 63 μm, [O III] 52 and 88 μm, [C II] 158 μm, and OH 119 μm absorption, within a reasonable integration time. These observations will enable us to investigate the connection between Lyman-continuum escape and far-infrared line properties, constrain the electron density, ionization state, and chemical abundance of the interstellar medium, and examine multiphase gas and outflows through the combination of optical and far-infrared diagnostics. The resulting dataset will provide an important local benchmark for interpreting future observations of distant galaxies with PRIMA and next-generation radio facilities.

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