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Register a new userPhysical properties and evolution of (Sub-)millimeter selected galaxies in the galaxy formation simulation Shark
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Claudia del P. Lagos
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We thoroughly explore the properties of (sub)-millimeter (mm) selected galaxies (SMGs) in the Shark semi-analytic model of galaxy formation. Compared to observations, the predicted number counts at wavelengths (lambda) 0.6-2mm and redshift distributions at 0.1-2mm, agree well. At the bright end (>1mJy), Shark galaxies are a mix of mergers and disk instabilities. These galaxies display a stacked FUV-to-FIR spectrum that agrees well with observations. We predict that current optical/NIR surveys are deep enough to detect bright (>1mJy) lambda=0.85-2mm-selected galaxies at z<5, but too shallow to detect counterparts at higher redshift. A James Webb Space Telescope 10,000s survey should detect all counterparts for galaxies with $S_{rm 0.85mm}>0.01$mJy. We predict SMGs disks contribute significantly (negligibly) to the rest-frame UV (IR). We investigate the 0<z<6 evolution of the intrinsic properties of >1mJy lambda=0.85-2mm-selected galaxies finding their: (i) stellar masses are $>10^{10.2}M_{odot}$, with the 2mm ones tracing the most massive galaxies ($>10^{11}M_{odot}$); (ii) specific star formation rates (SFR) are mildly (~3-10x) above the main sequence (MS); (iii) host halo masses are $gtrsim 10^{12.3}M_{odot}$, with 2mm galaxies tracing the most massive halos (proto-clusters); (iv) SMGs have lower dust masses ($approx 10^{8}M_{odot}$), higher dust temperatures ($approx 40-45$K) and higher rest-frame V-band attenuation (>1.5) than MS galaxies; (v) sizes decrease with redshift, from 4kpc at z=1 to <1kpc at z=4; (vi) the Carbon Monoxide line spectra of $S_{rm 0.85mm}>1$mJy sources peak at 4->3. Finally, we study the contribution of SMGs to the molecular gas and cosmic SFR density at 0<z<10, finding that >1mJy sources make a negligible contribution at z>3 and z>5, respectively, suggesting current observations have unveiled the majority of the star formation at 0<z<10.
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Formation and evolution of galaxies have been a central driving force in the studies of galaxies and cosmology. Recent studies provided a global picture of cosmic star formation history. However, what drives the evolution of star formation activities in galaxies has long been a matter of debate. The key factor of the star formation is the transition of hydrogen from atomic to molecular state, since the star formation is associated with the molecular phase. This transition is also strongly coupled with chemical evolution, because dust grains, i.e., tiny solid particles of heavy elements, play a critical role in molecular formation. Therefore, a comprehensive understanding of neutral-molecular gas transition, star formation and chemical enrichment is necessary to clarify the galaxy formation and evolution. Here we present the activity of SKA-JP galaxy evolution sub-science working group (subSWG) Our activity is focused on three epochs: z sim 0, 1, and z > 3. At z sim 0, we try to construct a unified picture of atomic and molecular hydrogen through nearby galaxies in terms of metallicity and other various ISM properties. Up to intermediate redshifts z sim 1, we explore scaling relations including gas and star formation properties, like the main sequence and the Kennicutt-Schmidt law of star forming galaxies. To connect the global studies with spatially-resolved investigations, such relations will be plausibly a viable way. For high redshift objects, the absorption lines of HI 21-cm line will be a very promising observable to explore the properties of gas in galaxies. By these studies, we will surely witness a real revolution in the studies of galaxies by SKA.
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