Advanced Camera for Surveys Photometry of the Cluster RDCS 1252.9–2927: The Color-Magnitude Relation at z = 1.24
Advanced Camera for Surveys Photometry of the Cluster RDCS 1252.9–2927: The Color-Magnitude Relation at z = 1.24
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DOI：
10.1086/379234
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发表时间：
2003-09
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通讯作者：
J. Blakeslee;M. Franx;M. Postman;M. Postman;P. Rosati;B. Holden;G. Illingworth;H. Ford;N. Cross;C. Gronwall;Narciso Benitez;R. Bouwens;T. Broadhurst;M. Clampin;R. Demarco;D. Golimowski;G. Hartig;L. Infante;A. R. Martel;G. Miley;F. Menanteau;G. Meurer;M. Sirianni;R. White;R. White
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文献类型：
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作者：
J. Blakeslee;M. Franx;M. Postman;M. Postman;P. Rosati;B. Holden;G. Illingworth;H. Ford;N. Cross;C. Gronwall;Narciso Benitez;R. Bouwens;T. Broadhurst;M. Clampin;R. Demarco;D. Golimowski;G. Hartig;L. Infante;A. R. Martel;G. Miley;F. Menanteau;G. Meurer;M. Sirianni;R. White;R. White
我们利用哈勃太空望远镜上的先进巡天相机在F775W和F850LP波段获得的图像，研究了遥远的x射线选择星团RDCS 1252.9-2927在z = 1.24处的星系色等（CM）关系。我们根据形态学分类选择星系，从星系光度函数向下延伸约3.5等，并通过光谱隶属度信息增强。在星团的核心是一个广泛的早期星系群，围绕着一对显示出动态相互作用迹象的星系。在CM图中，早期种群定义了一个紧密的序列，在52个星系中观测到（i775-z850）的本征散点为0.029±0.007等，在~30个椭圆星系中为0.024±0.008等。使用最新恒星群模型的模拟表明，椭圆星系的年龄分散约为34%，平均年龄τL≥2.6 Gyr（对应于zL≥2.7），最后恒星形成发生在zend≥1.5。转换到静止框架（U-B），我们得出结论，在形态选择的早期星系中，CM关系中的斜率和散射在z≈1.2范围内几乎没有演化的证据。因此，当宇宙只有现在年龄的三分之一时，椭圆星系已经在x射线发光的星团中很好地建立起来了。
We investigate the color-magnitude (CM) relation of galaxies in the distant X-ray-selected cluster RDCS 1252.9-2927 at z = 1.24 using images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope in the F775W and F850LP bandpasses. We select galaxies based on morphological classifications extending about 3.5 mag down the galaxy luminosity function, augmented by spectroscopic membership information. At the core of the cluster is an extensive early-type galaxy population surrounding a central pair of galaxies that show signs of dynamical interaction. The early-type population defines a tight sequence in the CM diagram, with an intrinsic scatter in observed (i775-z850) of 0.029 ± 0.007 mag based on 52 galaxies or 0.024 ± 0.008 mag for ~30 elliptical galaxies. Simulations using the latest stellar population models indicate an age scatter for the elliptical galaxies of about 34%, with a mean age τL ≳ 2.6 Gyr (corresponding to zL ≳ 2.7), and the last star formation occurring at zend ≳ 1.5. Transforming to rest-frame (U-B), we conclude that the slope and scatter in the CM relation for morphologically selected early-type galaxies show little or no evidence of evolution out to z ≈ 1.2. Thus, elliptical galaxies were already well established in X-ray-luminous clusters when the universe was a third of its present age.