An Intensely Star-Forming Galaxy at z~7 with Low Dust and Metal Content Revealed by Deep ALMA and HST Observations
Masami Ouchi, Richard Ellis, Yoshiaki Ono, Kouichiro Nakanishi, Kotaro Kohno, Rieko Momose, Yasutaka Kurono, M. L. N. Ashby, Kazuhiro Shimasaku, S. P. Willner, … 展开作者
Masami Ouchi, Richard Ellis, Yoshiaki Ono, Kouichiro Nakanishi, Kotaro Kohno, Rieko Momose, Yasutaka Kurono, M. L. N. Ashby, Kazuhiro Shimasaku, S. P. Willner, G. G. Fazio, Yoichi Tamura, Daisuke Iono
备注：
13 pages, 10 figures. Accepted for publication in ApJ. Revised [CII] detection limit, added Figure 8, conclusions unchanged
We report deep ALMA observations complemented with associated HST imaging for a luminous (m_uv=25) galaxy, `Himiko', at a redshift z=6.595. The galaxy is remarkable for its high star formation rate, 100 Mo/yr, securely estimated from our deep HST and Spitzer photometry, and the absence of any evidence for strong AGN activity or gravitational lensing magnification. Our ALMA observations probe an order of magnitude deeper than previous IRAM observations, yet fail to detect a 1.2mm dust continuum, indicating a flux <52uJy comparable with or weaker than that of local dwarf irregulars with much lower star formation rates. We likewise provide a strong upper limit for the flux of [CII] 158um, L([CII]) < 5.4x10^7 Lo, a diagnostic of the hot interstellar gas often described as a valuable probe for early galaxies. In fact, our observations indicate Himiko lies off the local L([CII]) - star formation rate scaling relation by a factor of more than 30. Both aspects of our ALMA observations suggest Himiko is an unique object with a very low dust content and perhaps nearly primordial interstellar gas. Our HST images provide unique insight into the morphology of this remarkable source, highlighting an extremely blue core of activity and two less extreme associated clumps. Himiko is undergoing a triple major merger event whose extensive ionized nebula of Lyman alpha emitting gas, discovered in our earlier work with Subaru, is powered by star formation and the dense circum-galactic gas. We are likely witnessing an early massive galaxy during a key period of its mass assembly close to the end of the reionization era.
MUSE-ALMA Haloes XIII. Molecular gas in $z \sim 0.5$ HI-selected galaxies
European Southern Observatory（欧洲南方天文台）；Aix Marseille Univ., CNRS, LAM, (Laboratoire d’Astrophysique de Marseille)（艾克斯-马赛大学、法国国家科学研究中心、天体物理学实验室）；Max-Planck-Institut für Extraterrestrische Physik (MPE)（马克斯·普朗克地外物理研究所）；Department of Physics and Astronomy, University of South Carolina（南卡罗来纳大学物理与天文学系）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理研究所）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理学与超级计算中心）；CSIRO Space & Astronomy（CSIRO空间与天文部）
