标题： 早期场椭圆星系的形成约束 显示英文标题

标题： Constraints on the Early Formation of Field Elliptical Galaxies

摘要： 我们呈现了涵盖哈勃深场及其侧翼区域的HK'大视场调查结果。 我们的大视场调查提供了61.8平方角分区域的均匀覆盖，深度相当于5倍标准差下的K=20.1。 我们还对哈勃深场进行了HK'成像，提供了7.8平方角分区域的均匀覆盖，深度相当于5倍标准差下的K=21.2。 结合这些数据以及在CFHT上获得的新深度UH 8K V和I成像，我们发现只有少量天体的颜色比I-K=4更红，这是红移大于1的演化椭圆星系预期的颜色。 我们推断，只有局部场椭圆星系群体中M_K<-23.4的一部分可能在高红移时以单次爆发形成。 显示英文摘要

摘要： We present the results of an HK' wide-field survey encompassing the Hubble Deep Field and its Flanking Fields. Our wide-field survey provides uniform coverage of an area 61.8 square arcmin to a depth equivalent to K=20.1 at 5-sigma. We have also imaged the Hubble Deep Field in HK', providing uniform coverage of an area 7.8 square arcmin to a depth equivalent to K=21.2 at 5-sigma. Using these data in combination with new deep UH 8K V and I imaging obtained on the CFHT, we find only a small population of objects with colors redder than an equivalent I-K=4, the color expected for an evolved elliptical at z>1. We infer that only a fraction of the local field elliptical population with M_K<-23.4 could have formed in single bursts at high redshift.