Groth Strip巡天中极红星系的形态和质量
The morphologies and masses of extremely red galaxies in the Groth Strip survey
摘要：
我们提出了一个新的目录EROs从Groth带，并研究它们的形态和质量之间的关系。我们在155弧分的测量区域内发现了102个ERO（F814 W-K =>4，K<=21.0）^[2]。测光数据包括U、B、F606 W、F814 W、J、K波段。形态是基于眼睛分类，我们区分3个基本类别：紧凑的对象，目标与光盘和/或凸起组件和不规则或合并的候选人。我们的大多数目标具有非常紧凑的形态（33 ± 6%），或显示或多或少不同的椎间盘成分（41 ± 6%）。14+-4%是合并或不规则的，7个对象无法分类。我们还研究了结构参数对形态外观的依赖性。无论是致密的还是显示出明显的凸起成分的ERO，其有效半径中值（1.22+-0.14 kpc和3.31+-0.53 kpc）都比盘主导的（5.50+-0.51 kpc）或可能的不规则星系或合并候选者（4.92+-0.14 kpc）小。Sersic指数分别从2.30 ± 0.34和3.24 ± 0.55变为1.03 ± 0.24和1.54 ± 0.40。我们样本中的大多数ERO的红移在z=1和z=2之间;然而，我们样本中的紧凑ERO在红移低至z=0.4和高至z=2.8时被发现;后者与DRG一样合格。在z=2.8时也发现了盘状ERO;然而，具有凸起盘结构的ERO仅在z<1.5时可见。对于这些ERO中的每一个，我们通过将合成的Bruzual（2007）光谱拟合到SED来确定恒星质量和平均人口年龄。质量估计是通过假设恒星形成率呈指数下降来获得的。恒星的总质量范围是9.1<log（M/M_sun）<11.6。我们不能检测到形态类的恒星质量分布之间的显着差异。质量log（M/M_sun）>11.0的ERO主要表现为致密形态，但也包括大量具有圆盘形态的源。
英文摘要：
We present a new cataloge of EROs from the Groth strip and study the relation between their morphology and mass. We find 102 EROs (F814W-K=>4, K<=21.0), over a survey area of 155 arcmin^2. The photometric data include U,B,F606W,F814W,J,K bands. Morphologies are based on a by eye classification and we distinguish between 3 basic classes: compact objects, targets with a disc and/or a bulge component and irregular or merger candidates. The majority of our targets has either a very compact morphology (33+-6%), or show more or less distinct disc components (41+-6%). 14+-4% are merger or irregulars and 7 objects could not be classified. We also study the dependence of structural parameters on morphological appearance. EROs that are either compact or show a distinct bulge component have smaller median effective radii (1.22+-0.14 kpc and 3.31+-0.53 kpc) than disc dominated (5.50+-0.51 kpc) or possible irregular galaxies or merger candidates (4.92+-0.14 kpc). The Sersic index changes from 2.30+-0.34 and 3.24+-0.55, to 1.03+-0.24 and 1.54+-0.40 respectively. Most the EROs in our sample have redshifts between z=1 and z=2; however, compact EROs in our sample are found at redshifts as low as z=0.4 and as high as z=2.8; the latter qualify as well as DRGs. Disc-like EROs are also found up to z=2.8; however those with a bulge-disc structure are only seen at z<1.5. For each of these EROs we determined the stellar mass and mean population age by fitting synthetic Bruzual (2007) spectra to the SED. Mass estimates were obtained by assuming an exponentially declining star formation rate. Total stellar masses are in the range 9.1<log(M/M_sun)<11.6. We cannot detect significant differences between the stellar mass distribution of the morphological classes. EROs with masses of log(M/M_sun)>11.0 dominantly show compact morphologies, but also include a significant number of sources with a disc morphology.
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