http://arxiv.org/abs/1703.02138

We present the large statistics of the galaxy effective radius in the rest-frame far-infrared (FIR) wavelength Re(FIR) obtained from 1258 deep Atacama Large Millimeter/submillimeter Array (ALMA) 1-mm band maps that are open for public by 2016 December. Our ALMA sample consists of 736 sources at z=0-6 that typically have the star-formation rate of ~50-1000 M$_{\odot}$/yr and the stellar mass of ~10$^{10}$-10$^{11.5}$ M$_{\odot}$. We homogeneously derive Re(FIR) and FIR luminosity L_FIR of our ALMA sources with the same uv-visibility method over the redshift range of z=0-6, carefully evaluating the selection incompleteness and the size measurement systematics by realistic Monte-Carlo simulations. We find that there is a positive correlation between Re(FIR) and L_FIR at the >99% significance level. Fitting the power-law function, Re(FIR) $\propto$ L_FIR$^{\alpha}$, we obtain the best-fit value of \alpha=0.26+/-0.06. Moreover, the average R_e(FIR) at a fixed L_FIR decreases toward high redshifts. The best-fit \alpha and the redshift evolution trend of Re(FIR) are similar to those of the galaxy effective radius in the rest-frame UV (optical) wavelength Re(UV) (Re(Opt.)) revealed by optical (near-infrared) Hubble Space Telescope (HST) studies. We compare Re(FIR) of our ALMA sources with Re(UV) and Re(Opt.) on the statistical and individual bases, and identify the significant trend that Re(FIR) is smaller than Re(UV) and Re(Opt.), which suggests that dusty starbursts take place in a compact region. We investigate details of the rest-frame UV and optical morphologies of our ALMA sources with deep HST imaging data, and find that 27% of our ALMA sources appear to be major mergers. Because the rest of the ALMA sources (73%) are compact isolated sources, dusty starbursts are triggered not only by major mergers but also the other mechanism(s).

Read this paper on arXiv…

S. Fujimoto, M. Ouchi, T. Shibuya, et. al.
Wed, 8 Mar 17
27/60

Comments: 19 pages, 13 figures. Submitted to ApJ