Publication Date:
2016-12-16
Description:
We present zoom-in, adaptive mesh refinement, high-resolution (~=30 pc) simulations of high-redshift ( z ~= 6) galaxies with the aim of characterizing their internal properties and interstellar medium. Among other features, we adopt a star formation model based on a physically sound molecular hydrogen prescription, and introduce a novel scheme for supernova feedback, stellar winds and dust-mediated radiation pressure. In the zoom-in simulation, the target halo hosts ‘Dahlia’, a galaxy with a stellar mass M * = 1.6 x 10 10 M , representative of a typical z ~ 6 Lyman-break galaxy. Dahlia has a total H 2 mass of 10 8.5 M that is mainly concentrated in a disc-like structure of effective radius ~=0.6 kpc and scale height ~=200 pc. Frequent mergers drive fresh gas towards the centre of the disc, sustaining a star formation rate per unit area of ~=15 M yr –1 kpc –2 . The disc is composed of dense ( n 25 cm –3 ), metal-rich ( Z ~= 0.5 Z ) gas that is pressure supported by radiation. We compute the 158 μm [C ii ] emission arising from Dahlia, and find that ~=95 per cent of the total [C ii ] luminosity ( $L_{\rm [C\,\small {II}]}\simeq 10^{7.5}\,{\rm L}_{{\odot }}$ ) arises from the H 2 disc. Although 30 per cent of the C ii mass is transported out of the disc by outflows, such gas negligibly contributes to [C ii ] emission, due to its low density ( n 10 cm –3 ) and metallicity ( Z 10 –1 Z ). Dahlia is underluminous with respect to the local [C ii ]–SFR relation; however, its luminosity is consistent with upper limits derived for most z ~ 6 galaxies.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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