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arXiv 1107.3137astro-ph.CO
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Z = 1.5-3.6的半乳糖醛酸的HST/WFC3-IR形态学研究:I.恒星形成星系的概况描述及其形态特征

An HST/WFC3-IR Morphological Survey of Galaxies at z = 1.5-3.6: I. Survey Description and Morphological Properties of Star Forming Galaxies

David R. Law, Charles C. Steidel, Alice E. Shapley, Sarah R. Nagy, Naveen A. Reddy, Dawn K. Erb

摘要:

我们提出了一个42轨道的HST/WFC 3调查的恒星形成星系的光谱红移范围z=1.5-3.6的静止框架光学形态的结果。该巡天由42个F160 W成像轨道组成,覆盖范围约为65弧分^[2],广泛分布在天空中,深度为27.9 AB,在0.2弧秒半径的孔径内进行5西格玛探测。通过对306个恒星质量在M* = 10^9 - 10^11 M太阳的恒星形成星系的光学选择样本进行研究,我们发现典型的圆形有效半光半径范围在0.7 - 3.0 kpc之间,并且早在z ~ 3时就描述了恒星质量-半径关系。虽然这些星系最好用指数表面亮度剖面来描述,但它们的轴比分布与倾斜指数盘的分布非常不一致,并且可以用短轴/长轴比约为0.3和中轴/长轴比约为0.7的三轴恒星系统来更好地再现。虽然HST/ACS成像数据中的一部分星系的静止紫外和静止光学形态基本相似,但在质量M* > 3 x 10^10 Msun的情况下,差异更为明显。最后,我们讨论了星系形态的背景下,努力限制合并分数,发现形态识别的合并/非合并一般有显着差异的物理观测量,如恒星质量和恒星形成率,虽然合并类星系根据一些标准选择有统计学上较小的有效半径和相应的较大的SFR面密度。

英文摘要:

We present the results of a 42-orbit HST/WFC3 survey of the rest-frame optical morphologies of star forming galaxies with spectroscopic redshifts in the range z=1.5-3.6. The survey consists of 42 orbits of F160W imaging covering ~65 arcmin^2 distributed widely across the sky and reaching a depth of 27.9 AB for a 5 sigma detection within a 0.2 arcsec radius aperture. Focusing on an optically selected sample of 306 star forming galaxies with stellar masses in the range M* = 10^9 - 10^11 Msun, we find that typical circularized effective half-light radii range from ~ 0.7 - 3.0 kpc and describe a stellar mass - radius relation as early as z ~ 3. While these galaxies are best described by an exponential surface brightness profile, their distribution of axis ratios is strongly inconsistent with a population of inclined exponential disks and is better reproduced by triaxial stellar systems with minor/major and intermediate/major axis ratios ~ 0.3 and 0.7 respectively. While rest-UV and rest-optical morphologies are generally similar for a subset of galaxies with HST/ACS imaging data, differences are more pronounced at higher masses M* > 3 x 10^10 Msun. Finally, we discuss galaxy morphology in the context of efforts to constrain the merger fraction, finding that morphologically-identified mergers/non-mergers generally have insignificant differences in terms of physical observables such as stellar mass and star formation rate, although merger-like galaxies selected according to some criteria have statistically smaller effective radii and correspondingly larger SFR surface density.

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