An Optical Near-Infrared Study of Radio-loud Quasar Environments. I. Methods and z = 1-2 Observations
An Optical Near-Infrared Study of Radio-loud Quasar Environments. I. Methods and z = 1-2 Observations
复制标题
射电强类星体环境的光学近红外研究。
DOI：
10.1086/313149
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
M. Cohen
中科院分区：
文献类型：
--
作者：
P. Hall;R. Green;M. Cohen
我们对红移z = 0.6-2.0的射电响亮类星体（RLQs）的环境进行了光学/近红外研究。在本文中，我们讨论了z = 1.0-2.0子样本的样本选择和观测，以及所使用的缩减和编目技术。由于目前在单一文献参考中很少有关于近红外数据还原和多色对象编目的详细描述，因此我们对技术问题进行了一定的讨论。我们的33个rlq样本包含相当数量的平坦和陡峭的无线电频谱源以及各种无线电形态的源，并且跨越了类似的mab和Prad范围，这使我们能够从红移演化中分离出环境对光学或无线电亮度的依赖。我们使用标准的“移动和注视”方法来创建深度拼接图像，其中每个像素的曝光时间（因此rms噪声）在马赛克中不是恒定的。我们的简化过程的一个不寻常的特点是，从这样的马赛克中产生具有恒定rms噪声的图像。我们采用了这一程序，以便在几乎整个马赛克上使用FOCAS检测包，而不仅仅是在rms噪声恒定的最深观测区域，从而大致使我们的面积覆盖范围翻倍。我们使用科恩的SKY模型修正了我们视场中恒星污染的天体数量，并将星系数量与随机视场中的星系数量进行了比较。即使在考虑了可能的系统星等偏移之后，我们也发现了K > 19星系的大量过剩。霍尔和格林对这一过剩人口进行了分析和讨论。
We have conducted an optical/near-infrared study of the environments of radio-loud quasars (RLQs) at redshifts z = 0.6-2.0. In this paper we discuss the sample selection and observations for the z = 1.0-2.0 subsample and the reduction and cataloging techniques used. We discuss technical issues at some length, since few detailed descriptions of near-IR data reduction and multicolor object cataloging are currently available in single literature references. Our sample of 33 RLQs contains comparable numbers of flat and steep radio spectrum sources and sources of various radio morphologies and spans a similar range of Mabs and Prad, which allows us to disentangle dependence of environment on optical or radio luminosity from redshift evolution. We use the standard "shift-and-stare" method of creating deep mosaicked images in which the exposure time (and thus the rms noise) at each pixel is not constant across the mosaic. An unusual feature of our reduction procedure is the creation of images with constant rms noise from such mosaics. We adopted this procedure to enable use of the FOCAS detection package over almost the entire mosaic instead of only in the area of deepest observation where the rms noise is constant, thereby roughly doubling our areal coverage. We correct the object counts in our fields for stellar contamination using the SKY model of Cohen and compare the galaxy counts to those in random fields. Even after accounting for possible systematic magnitude offsets, we find a significant excess of K ≳ 19 galaxies. Analysis and discussion of this excess population is presented by Hall & Green.