Witstok, J, Smit, R, Maiolino, R, Kumari, N, Aravena, M, Boogaard, L, Bouwens, R, Carniani, S, Hodge, JA, Jones, GC, Stefanon, M, Van Der Werf, P and Schouws, S (2022) Dual constraints with ALMA: new [O iii] 88-μm and dust-continuum observations reveal the ISM conditions of luminous LBGs at z ∼7. Monthly Notices of the Royal Astronomical Society, 515 (2). pp. 1751-1773. ISSN 0035-8711

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Abstract

We present new [ O III] 88- μ m observations of five bright z ∼7 Lyman-break galaxies spectroscopically confirmed by ALMA through [ C II] 158 μ m, unlike recent [ O III] detections where Lyman α was used. This nearly doubles the sample of Epoch of Reionization galaxies with robust (5σ) [ C II] and [ O III] detections. We perform a multiwavelength comparison with new deep HST images of the rest-frame UV, whose compact morphology aligns well with [ O III] tracing ionized gas. In contrast, we find more spatially extended [ C II] emission likely produced in neutral gas, as indicated by an [ N II] 205- μm non-detection in one source. We find a correlation between the optical [O III]+ H β equivalent width and [ O III]/[ C II], as seen in local metal-poor dwarf galaxies. cloudy models of a nebula of typical density harbouring a young stellar population with a high-ionization parameter adequately reproduce the observed lines. Surprisingly, however, our models fail to reproduce the strength of [ O III] 88- μ m, unless we assume an α/Fe enhancement and near-solar nebular oxygen abundance. On spatially resolved scales, we find [ O III]/[ C II] shows a tentative anticorrelation with infrared excess, LIR/LUV, also seen on global scales in the local Universe. Finally, we introduce the far-infrared spectral energy distribution fitting code mercurius to show that dust-continuum measurements of one source appear to favour a low dust temperature and correspondingly high dust mass. This implies a high stellar metallicity yield and may point towards the need of dust production or grain-growth mechanisms beyond supernovae.

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
Publisher:	Oxford University Press (OUP)
SWORD Depositor:	A Symplectic
Date Deposited:	21 Sep 2022 11:43
Last Modified:	21 Sep 2022 11:45
DOI or ID number:	10.1093/mnras/stac1905
URI:	https://researchonline.ljmu.ac.uk/id/eprint/17649

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