1 research outputs found
Identification of Large Equivalent Width Dusty Galaxies at 4 z 6 from Sub-mm Colours
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.Comment: Paper accepted in Astronomy and Astrophysics on 10 November 202