Johnson Traci L, Rigby Jane R, Sharon Keren, Gladders Michael D, Florian Michael, Bayliss Matthew B, Wuyts Eva, Whitaker Katherine E, Livermore Rachael, Murray Katherine T
University of Michigan, Department of Astronomy, 1085 South University Avenue, Ann Arbor, MI 48109, USA.
Observational Cosmology Lab, NASA Goddard Space Flight Center, Greenbelt MD 20771, USA.
Astrophys J Lett. 2017 Jul 10;843(No 2). doi: 10.3847/2041-8213/aa7516. Epub 2017 Jul 6.
We present measurements of the surface density of star formation, the star-forming clump luminosity function, and the clump size distribution function, for the lensed galaxy SGAS J111020.0+645950.8 at a redshift of =2.481. The physical size scales that we probe, radii = 30-50 pc, are considerably smaller scales than have yet been studied at these redshifts. The star formation surface density we find within these small clumps is consistent with surface densities measured previously for other lensed galaxies at similar redshift. Twenty-two percent of the rest-frame ultraviolet light in this lensed galaxy arises from small clumps, with <100 pc. Within the range of overlap, the clump luminosity function measured for this lensed galaxy is remarkably similar to those of ∼ 0 galaxies. In this galaxy, star-forming regions smaller than 100 pc-physical scales not usually resolved at these redshifts by current telescopes-are important locations of star formation in the distant universe. If this galaxy is representative, this may contradict the theoretical picture in which the critical size scale for star formation in the distant universe is of order 1 kiloparsec. Instead, our results suggest that current telescopes have not yet resolved the critical size scales of star-forming activity in galaxies over most of cosmic time.
我们给出了红移为 (z = 2.481) 的引力透镜星系 SGAS J111020.0+645950.8 的恒星形成表面密度、恒星形成团块光度函数和团块大小分布函数的测量结果。我们探测的物理尺寸尺度，即半径 (r = 30 - 50) 秒差距，比在这些红移下迄今所研究的尺度要小得多。我们在这些小团块中发现的恒星形成表面密度与之前在类似红移下对其他引力透镜星系测量的表面密度一致。这个引力透镜星系中 22% 的静止帧紫外光来自半径 (r < 100) 秒差距的小团块。在重叠范围内，这个引力透镜星系的团块光度函数与大约 (z \sim 0) 的星系的团块光度函数非常相似。在这个星系中，小于 100 秒差距的恒星形成区域（当前望远镜在这些红移下通常无法分辨的物理尺度）是遥远宇宙中恒星形成的重要场所。如果这个星系具有代表性，这可能与遥远宇宙中恒星形成的临界尺寸尺度约为 1 千秒差距的理论图景相矛盾。相反，我们的结果表明，在宇宙大部分时间里，当前望远镜尚未分辨出星系中恒星形成活动的临界尺寸尺度。
