Luminous Compact Blue Galaxies up to z ~ 1 in the Hubble Space Telescope Ultra Deep Field. I. Small Galaxies or Blue Centers of Massive Disks?
Luminous Compact Blue Galaxies up to z ~ 1 in the Hubble Space Telescope Ultra Deep Field. I. Small Galaxies or Blue Centers of Massive Disks?
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DOI：
10.1086/503556
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发表时间：
2006-02
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通讯作者：
K. Noeske;D. Koo;A. Phillips;C. Willmer;J. Melbourne;A. Paz;P. P. L. Observatory-P.;Santa Cruz;Usa Carnegie Observatories;Pasadena;Usa;Institute for Theoretical Astrophysics;Goettingen;H Germany
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作者：
K. Noeske;D. Koo;A. Phillips;C. Willmer;J. Melbourne;A. Paz;P. P. L. Observatory-P.;Santa Cruz;Usa Carnegie Observatories;Pasadena;Usa;Institute for Theoretical Astrophysics;Goettingen;H Germany
我们分析了哈勃太空望远镜ACS超深场（UDF）在z ~ 0.2-1.3波段的26个发光紧凑型蓝色星系（lcbg），以确定它们是否真的是小星系，或者更确切地说，是存在或正在形成的大型盘状星系中的明亮中央星暴。即使对于z ~ 1的致密物体，UDF图像的表面亮度曲线也比静止帧26.5 B等arcsec-2暗淡。大多数lcbg显示出一个更小、更亮的成分，可能是恒星形成的成分，以及一个扩展的、大致呈指数的成分，其颜色表明恒星的年龄从100迈到几十亿年不等。扩展组分的尺度长度大多为> 2 kpc，比邻近的大盘状星系（如银河系）的尺度长度小1.5-2倍以上。更大的、表面亮度非常低的星盘可以被排除在外，直到微弱的静帧表面亮度（≥26b等arcsec-2）。然而，有一两个LCBG是大型的圆盘状星系，因为有一个明亮的中心核，可能是一个正在形成的凸起，所以符合LCBG的选择标准。这些结果表明，假设被动演化和没有显著的盘状增长，高z lcbg的约90%是小星系，它们将演化成小的盘状星系，或者在局部宇宙中演化成低质量的球状星系或不规则星系。这些数据并没有揭示出在类似H星系的小型lcbg周围有圆盘形成的迹象，也没有提出一个简单的由内而外的圆盘状大型lcbg生长场景。在遥远的LCBG中，不规则的蓝色发射相对较长，这表明来自恒星形成区域的星云发射线是LCBG速度场的主要部分。
We analyze 26 luminous compact blue galaxies (LCBGs) in the Hubble Space Telescope ACS Ultra Deep Field (UDF) at z ~ 0.2-1.3, to determine whether these truly are small galaxies or, rather, bright central starbursts within existing or forming large disk galaxies. Surface brightness profiles from UDF images reach fainter than rest-frame 26.5 B mag arcsec-2 even for compact objects at z ~ 1. Most LCBGs show a smaller, brighter component that is likely star-forming, and an extended, roughly exponential component with colors suggesting stellar ages from ≳100 Myr to a few gigayears. Scale lengths of the extended components are mostly ≲2 kpc, more than 1.5-2 times smaller than those of nearby large disk galaxies like the Milky Way. Larger, very low surface brightness disks can be excluded down to faint rest-frame surface brightnesses (≳26 B mag arcsec-2). However, one or two of the LCBGs are large, disklike galaxies that meet LCBG selection criteria because of a bright central nucleus, possibly a forming bulge. These results indicate that ≳90% of high-z LCBGs are small galaxies that will evolve into small disk galaxies, or low-mass spheroidal or irregular galaxies in the local universe, assuming passive evolution and no significant disk growth. The data do not reveal signs of disk formation around small, H II galaxy-like LCBGs, nor do they suggest a simple inside-out growth scenario for larger LCBGs with a disklike morphology. Irregular blue emission in distant LCBGs is relatively extended, suggesting that nebular emission lines from star-forming regions sample a major fraction of an LCBG's velocity field.