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arXiv · 2211.05744

Identification of Large Equivalent Width Dusty Galaxies at 4 $<$ z $<$ 6 from Sub-mm Colours

Denis Burgarella·Patrice Theulé·Véronique Buat·Lisa Gouiran·Lorie Turco·Médéric Boquien·Tom J. L. C. Bakx·Akio K. Inoue·Yoshinobu Fudamoto·Yuma Sugahara·Jorge Zavala
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Abstract

Infrared (IR), sub-millimetre (sub-mm) and millimetre (mm) databases contain a huge quantity of high quality data. However, a large part of these data are photometric, and are thought not to be useful to derive a quantitative information on the nebular emission of galaxies. The aim of this project is first to identify galaxies at z > 4-6, and in the epoch of reionization from their sub-mm colours. We also aim at showing that the colours can be used to try and derive physical constraints from photometric bands, when accounting for the contribution from the IR fine structure lines to these photometric bands. We model the flux of IR fine structure lines with CLOUDY, and add them to the dust continuum emission with CIGALE. Including or not emission lines in the simulated spectral energy distribution (SED) modifies the broad band emission and colours. The introduction of the lines allows to identify strong star forming galaxies at z > 4 - 6 from the log10 (PSW_250um/PMW_350um) versus log10 (LABOCA_870um/PLW_500um) colour-colour diagramme. By comparing the relevant models to each observed galaxy colour, we are able to roughly estimate the fluxes of the lines, and the associated nebular parameters. This method allows to identify a double sequence in a plot built from the ionization parameter and the gas metallicity. The HII and photodissociation region (PDR) fine structure lines are an essential part of the SEDs. It is important to add them when modelling the spectra, especially at z > 4 - 6 where their equivalent widths can be large. Conversely, we show that we can extract some information on strong IR fine structure lines and on the physical parameters related to the nebular emission from IR colour-colour diagrams.

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Denis Burgarella, Patrice Theulé, Véronique Buat, Lisa Gouiran, Lorie Turco, Médéric Boquien, Tom J. L. C. Bakx, Akio K. Inoue, Yoshinobu Fudamoto, Yuma Sugahara, Jorge Zavala. 2022-11-10. Identification of Large Equivalent Width Dusty Galaxies at 4 $<$ z $<$ 6 from Sub-mm Colours. https://doi.org/10.1051/0004-6361%2F202244491

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