http://arxiv.org/abs/1402.5145
[Abridged] We predict nebular emission from star-forming galaxies within a cosmological galaxy formation model. Emission lines are computed by combining the semi-analytical model SAG with the photo-ionization code MAPPINGS-III. We characterise the interstellar medium (ISM) of galaxies by relating the ionization parameter of gas in galaxies to their cold gas metallicity. Our model is in reasonable agreement with the observed H-alpha, [OII] and [OIII] luminosity functions. Also, the model reproduces the star-forming sequence of the BPT diagram for local galaxies and the observed H-alpha to [OII] line ratios at high redshift. The average ionization parameter predicted for galaxies is found to increase in galaxies with low star-formation rates and also towards higher redshifts, in agreement with recent observational results. We study the relation between the star-formation rate of galaxies and their emission line luminosities as a function of redshift, finding strong correlations between different emission lines and their star-formation rates. We present scaling relations that can be used to infer the star-formation rate using only single line luminosities. Our model predicts that high redshift emission line galaxies have modest clustering bias, and thus reside in by dark matter haloes of masses below M< 10^(12) [h^(-1)M_sun], consistent with observational estimates of the clustering of emission lines. We present predictions for the number of star-forming galaxies that can be detected at redshifts up to z~10 by targeting different far-infrared (FIR) emission lines with submillimetre facilities such as the Atacama Large Millimeter Array (ALMA). Finally, we discuss the limitations of our modelling technique and the possible ways to extend it.
A. Orsi, N. Padilla, B. Groves, et. al.
Mon, 24 Feb 14
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