A V-Band Survey for Variable Galactic Nuclei in the Hubble Deep Field
A V-Band Survey for Variable Galactic Nuclei in the Hubble Deep Field
复制标题
哈勃深场中变星系核的 V 波段巡天
DOI：
10.1086/379168
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
C. Kasm
中科院分区：
文献类型：
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作者：
V. Sarajedini;R. Gilliland;C. Kasm
我们展示了哈勃深场两纪元变异性调查的结果，目的是调查 z ≃ 1 范围内的活动星系核 (AGN) 数量。哈勃太空望远镜的高分辨率和稳定性允许在亚角秒孔径内获得精确的光度测量，从而能够探测比地面低得多的 AGN/宿主星系光度比。分析星系变率的主要数据集是 1995 年 12 月获得的原始哈勃深场观测数据和几乎恰好 5 年后的 2000 年获得的第二张 V 波段 (F606W) 图像。我们在 217 个星系中的 16 个中发现了核变率的证据，这些星系比 Vnuc = 27.5 亮。校正不完整性和虚假检测后，变核约占所调查星系的 8%。这些光源的红移范围为 0.09 < z < 1.8，涵盖了星系核 V-I 颜色的全部范围。我们的七个可变源与钱德拉女士的两次调查中检测到的 X 射线源一致，其中六个来自主目录，一个来自补充目录。我们发现 44% 的可变核与 15 μm 的中红外检测相关，31% 在 1.4 GHz 处检测到。光谱可用于 16 个变量中的 13 个。一种是宽线活动星系核，另外两种则显示出 2 型活动星系核的微弱证据。假设这些变量都是活动核，我们估计 AGN 光度函数 (LF) 在 0.4 < z < 1.1 处，延伸到 MB ≃ -15。与局部 Seyfert 光度函数相比，我们发现微弱活动星系核的数量密度增加的证据。光学变化原子核的 LF 数密度似乎有所增加，但没有证据表明在这些微弱的量级上发生了翻转。
We present the results of a two-epoch variability survey in the Hubble Deep Field with the goal of investigating the population of active galactic nuclei (AGNs) to z ≃ 1. The high resolution and stability of the Hubble Space Telescope allow accurate photometry to be obtained within subarcsecond apertures, resulting in the ability to probe much lower AGN/host galaxy luminosity ratios than can be done from the ground. The primary data sets analyzed for galactic variability are the original Hubble Deep Field observations obtained in 1995 December and a second V-band (F606W) image obtained almost exactly 5 yr later in 2000. We find evidence for nuclear variability in 16 of 217 galaxies brighter than Vnuc = 27.5. Correcting for incompleteness and spurious detections, variable nuclei make up ~8% of the surveyed galaxies. These sources have a redshift range of 0.09 < z < 1.8 and cover the full range of galaxy nuclear V-I colors. Seven of our variable sources are coincident with X-ray sources detected in the 2 Ms Chandra survey, six from the main catalog and one from the supplementary catalog. We find that 44% of the variable nuclei are associated with mid-IR detections at 15 μm, and 31% are detected at 1.4 GHz. Optical spectra are available for 13 of the 16 variables. One is a broad-line AGN, and two others show weak evidence of type 2 AGNs. With the assumption that these variables are all active nuclei, we estimate the AGN luminosity function (LF) at 0.4 < z < 1.1 extending to MB ≃ -15. We find evidence for an increase in the number density of faint AGNs when comparing to the local Seyfert luminosity function. The LF for optically varying nuclei appears to rise in number density, with no evidence of turning over at these faint magnitudes.