Kumari, N, Smit, R, Leitherer, C, Witstok, J, Irwin, MJ, Sirianni, M and Aloisi, A (2024) A study of extreme C III]1908 & [O III]88/[C II]157 emission in Pox 186: implications for JWST+ALMA (FUV + FIR) studies of distant galaxies. Monthly Notices of the Royal Astronomical Society, 529 (2). pp. 781-801. ISSN 0035-8711

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Abstract

Carbon spectral features are ubiquitous in the ultraviolet (UV) and far-infrared (FIR) spectra of the reionization-era galaxies. We probe the ionized carbon content of a dwarf galaxy Pox 186 using the UV, optical, mid-infrared, and FIR data taken with Hubble, Gemini, Spitzer, and Herschel, respectively. This local (z ∼ 0.0040705) galaxy is likely an analogue of reionization-era galaxies, as revealed by its extreme FIR emission line ratio, [O III] 88 μm/[C II] 157 μm (>10). The UV spectra reveal extreme C III] λλ1907, 1909 emission with the strongest equivalent width (EW) = 35.85 ± 0.73 Å detected so far in the local (z ∼ 0) Universe, a relatively strong C IV λλ1548, 1550 emission with EW = 7.95 ± 0.45 Å, but no He II λ1640 detection. Several scenarios are explored to explain the high EW of carbon lines, including high effective temperature, high carbon-to-oxygen ratio, slope, and upper mass of top-heavy initial mass function, hard ionizing radiation, and in-homogeneous dust distribution. Both C III] and C IV line profiles are broadened with respect to the O III] λ1666 emission line. Each emission line of C IV λλ1548, 1550 shows the most distinct double-peak structure ever detected, which we model via two scenarios, firstly a double-peaked profile that might emerge from resonant scattering and secondly, a single nebular emission line along with a weaker interstellar absorption. The study demonstrates that galaxies with extreme FIR properties may also show extreme UV properties, hence paving a promising avenue of using FIR+UV in the local (via Hubble+Herschel/SOFIA) and distant (via JWST + ALMA) Universe for unveiling the mysteries of the reionization-era.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute Biological & Environmental Sciences (from Sep 19)
Publisher:	Oxford University Press (OUP)
SWORD Depositor:	A Symplectic
Date Deposited:	20 Aug 2024 11:53
Last Modified:	20 Aug 2024 12:00
DOI or ID number:	10.1093/mnras/stae252
URI:	https://researchonline.ljmu.ac.uk/id/eprint/23993

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