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arXiv 0807.2281astro-ph
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HST和VLA FIRST巡天观测到的Millijansky射电星系的光学形态

Optical Morphologies of Millijansky Radio Galaxies Observed by HST and in the VLA FIRST Survey

J. Russell, R. E. Ryan,, S. H. Cohen, R. A. Windhorst, I. Waddington

摘要:

本文报道了利用哈勃空间望远镜观测到的射电天空20厘米处的微弱图像中的51个射电星系在毫扬斯基通量水平上的统计研究,包括它们的光学形态和结构。我们的光学成像比以前的研究更深(~2等),具有空间成像的优越角分辨率。我们发现8/51(16%)的射电源没有光学可识别的对应物AB~24 mag.对于其余的43源,只有25是充分解决的HST图像可靠地分配一个视觉分类:15个(60%)是椭圆星系,2个(8%)是晚型螺旋星系,1个(4%)是S 0,3个(12%)是点状物体(类星体),4个(16%)是合并系统。我们发现一个类似的分布的光学类型与测量的Sersic指数。这些星系的光学星等分布峰值在I~20.7+-0.5AB等,比我们典型的HST场的深度亮约3等,因此不是由于WFPC 2的探测极限。这支持了光度依赖密度演化模型,其中大多数微弱射电星系通常具有L* 光学光度和z~0.8的中位红移,在z>~2时相对突然的红移截止。我们讨论我们的结果的背景下,椭圆星系和活动星系核的演化。

英文摘要:

We report on a statistical study of the 51 radio galaxies at the millijansky flux level from the Faint Images of the Radio Sky at Twenty centimeters, including their optical morphologies and structure obtained with the Hubble Space Telescope. Our optical imaging is significantly deeper (~2 mag) than previous studies with the superior angular resolution of space-based imaging. We that find 8/51 (16%) of the radio sources have no optically identifiable counterpart to AB~24 mag. For the remaining 43 sources, only 25 are sufficiently resolved in the HST images to reliably assign a visual classification: 15 (60%) are elliptical galaxies, 2 (8%) are late-type spiral galaxies, 1 (4%) is an S0, 3 (12%) are point-like objects (quasars), and 4 (16%) are merger systems. We find a similar distribution of optical types with measurements of the Sersic index. The optical magnitude distribution of these galaxies peaks at I~20.7+-0.5 AB mag, which is ~3 mag brighter than the depth of our typical HST field and is thus not due to the WFPC2 detection limit. This supports the luminosity-dependent density evolutionary model, where the majority of faint radio galaxies typically have L*-optical luminosities and a median redshift of z~0.8 with a relatively abrupt redshift cut-off at z>~2. We discuss our results in the context of the evolution of elliptical galaxies and active galactic nuclei.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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