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arXiv · 1508.05950

SXDF-ALMA 1.5 arcmin^2 deep survey. A compact dusty star-forming galaxy at z=2.5

Ken-ichi Tadaki·Kotaro Kohno·Tadayuki Kodama·Soh Ikarashi·Itziar Aretxaga·Stefano Berta·Karina I. Caputi·James S. Dunlop·Bunyo Hatsukade·Masao Hayashi·David H. Hughes·Rob Ivison·Takuma Izumi·Yusei Koyama·Dieter Lutz·Ryu Makiya·Yuichi Matsuda·Kouichiro Nakanishi·Wiphu Rujopakarn·Yoichi Tamura·Hideki Umehata·Wei-Hao Wang·Grant W. Wilson·Stijn Wuyts·Yuki Yamaguchi·Min S. Yun
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Abstract

We present first results from the SXDF-ALMA 1.5 arcmin^2 deep survey at 1.1 mm using Atacama Large Millimeter Array (ALMA). The map reaches a 1sigma depth of 55 uJy/beam and covers 12 Halpha-selected star-forming galaxies at z = 2.19 or z=2.53. We have detected continuum emission from three of our Halpha-selected sample, including one compact star-forming galaxy with high stellar surface density, NB2315-07. They are all red in the rest-frame optical and have stellar masses of log (M*/Msun)>10.9 whereas the other blue, main-sequence galaxies with log(M*/Msun)=10.0-10.8 are exceedingly faint, <290 uJy (2sigma upper limit). We also find the 1.1 mm-brightest galaxy, NB2315-02, to be associated with a compact (R_e=0.7+-0.1 kpc), dusty star-forming component. Given high gas fraction (44^{+20}_{-8}% or 37^{+25}_{-3}%) and high star formation rate surface density (126^{+27}_{-30} Msun yr^{-1}kpc^{-2}), the concentrated starburst can within less than 50^{+12}_{-11} Myr build up a stellar surface density matching that of massive compact galaxies at z~2, provided at least 19+-3% of the total gas is converted into stars in the galaxy centre. On the other hand, NB2315-07, which already has such a high stellar surface density core, shows a gas fraction (23+-8%) and is located in the lower envelope of the star formation main-sequence. This compact less star-forming galaxy is likely to be in an intermediate phase between compact dusty star-forming and quiescent galaxies.

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Ken-ichi Tadaki, Kotaro Kohno, Tadayuki Kodama, Soh Ikarashi, Itziar Aretxaga, Stefano Berta, Karina I. Caputi, James S. Dunlop, Bunyo Hatsukade, Masao Hayashi, David H. Hughes, Rob Ivison, Takuma Izumi, Yusei Koyama, Dieter Lutz, Ryu Makiya, Yuichi Matsuda, Kouichiro Nakanishi, Wiphu Rujopakarn, Yoichi Tamura, Hideki Umehata, Wei-Hao Wang, Grant W. Wilson, Stijn Wuyts, Yuki Yamaguchi, Min S. Yun. 2015-08-24. SXDF-ALMA 1.5 arcmin^2 deep survey. A compact dusty star-forming galaxy at z=2.5. https://doi.org/10.1088/2041-8205%2F811%2F1%2Fl3

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