EVOLUTION OF THE SIZES OF GALAXIES OVER 7 < z < 12 REVEALED BY THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN
EVOLUTION OF THE SIZES OF GALAXIES OVER 7 < z < 12 REVEALED BY THE 2012 HUBBLE ULTRA DEEP FIELD CAMPAIGN
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DOI：
10.1088/0004-637x/777/2/155
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发表时间：
2012-12
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影响因子：
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通讯作者：
Y. Ono;M. Ouchi;E. Curtis-Lake;M. Schenker;R. Ellis;R. McLure;J. Dunlop;B. Robertson;A. Koekemoer;R. Bowler;A. B. Rogers;E. Schneider;S. Charlot;D. Stark;K. Shimasaku;S. Furlanetto;M. Cirasuolo
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作者：
Y. Ono;M. Ouchi;E. Curtis-Lake;M. Schenker;R. Ellis;R. McLure;J. Dunlop;B. Robertson;A. Koekemoer;R. Bowler;A. B. Rogers;E. Schneider;S. Charlot;D. Stark;K. Shimasaku;S. Furlanetto;M. Cirasuolo
我们使用2012年哈勃超深场活动的深层图像分析了红移范围为z∼7-12的失落候选星系的红移和光度相关的大小，这比以前的工作提供了两个优点。首先，我们利用UDF12成像提供的更高的信噪比，为HUDF6.5-8处的已知星系提供更好的测量结果。其次，由于UDF12数据允许在z>；8的HUDF中建立第一个健壮的星系样本，我们已经能够将对平均星系大小的测量扩展到更高的红移。将我们的测量局限于在>；15σ探测到的源，我们证实了早先的迹象，即z∼7-12星系的平均半光半径非常小，仅为0.3kpc-0.4kpc，与本地恒星形成星系中的巨型分子缔合的大小相当。我们还证实了半光半径随红移的增加而减小的明显趋势，并首次提供了这种趋势持续到z≃8以后的证据。将平均半光半径的演化模拟为幂函数∝(1+z)S，我们得到了一个超过z∼4-12的最佳拟合指数。这个关系可以用恒星在光度范围内形成的恒定表面密度来解释。消失星系的平均恒星形成面密度比极端星暴星系低2-3个数量级，但与今天在正常盘星系中心看到的相当。
We analyze the redshift- and luminosity-dependent sizes of dropout galaxy candidates in the redshift range z ∼ 7–12 using deep images from the 2012 Hubble Ultra Deep Field (UDF12) campaign, which offers two advantages over that used in earlier work. First, we utilize the increased signal-to-noise ratio offered by the UDF12 imaging to provide improved measurements for known galaxies at z ≃ 6.5–8 in the HUDF. Second, because the UDF12 data have allowed the construction of the first robust galaxy sample in the HUDF at z > 8, we have been able to extend the measurement of average galaxy size out to higher redshifts. Restricting our measurements to sources detected at >15σ, we confirm earlier indications that the average half-light radii of z ∼ 7–12 galaxies are extremely small, 0.3–0.4 kpc, comparable to the sizes of giant molecular associations in local star-forming galaxies. We also confirm that there is a clear trend of decreasing half-light radius with increasing redshift, and provide the first evidence that this trend continues beyond z ≃ 8. Modeling the evolution of the average half-light radius as a power law, ∝(1 + z)s, we obtain a best-fit index of over z ∼ 4–12. A clear size–luminosity relation is evident in our dropout samples. This relation can be interpreted in terms of a constant surface density of star formation over a range in luminosity of . The average star formation surface density in dropout galaxies is 2–3 orders of magnitude lower than that found in extreme starburst galaxies, but is comparable to that seen today in the centers of normal disk galaxies.