An X-Ray and Optical Investigation of the Environments around Nearby Radio Galaxies
An X-Ray and Optical Investigation of the Environments around Nearby Radio Galaxies
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对附近射电星系周围环境的 X 射线和光学研究
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
W. Voges
中科院分区：
文献类型：
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作者：
N. Miller;F. Owen;J. Burns;M. Ledlow;W. Voges
对射电源群集环境的研究没有显示出无线电功率与群集程度之间的相关性。然而，已经证明扩展的x射线光度和星系群集确实表现出正相关。这项研究调查了25个附近（z≤0.06）射电星系的完整样本，这些星系不是Abell星系团的成员。通过ROSAT全天巡天（RASS）、ROSAT定点观测和Palomar光学数字化巡天（DSS），研究了这些射电星系的x射线和光学环境。x射线的亮度和程度由RASS确定，DSS通过空间两点相关系数Bgg来量化聚类程度。在25个源中，20个在x射线中有≥3 σ的探测，11个源具有明显超过孤立星系预期的Bgg。加上x射线发射被分解的标准，10个射电星系似乎确实存在于糟糕的星团中，它们的x射线发射延长了，这表明星团内介质的存在。其中8个星系还具有很高的空间相关系数。综上所述，这些数据表明，射电星系位于阿贝尔星系团的低丰度延伸区。来自其他星系的未解析的x射线发射很可能与活动星系核现象有关。此外，尽管样本量很小，但似乎FR I和FR II源的环境不同。FR I往往更频繁地与扩展x射线发射有关（18个中的10个），而FR II通常是点源或在x射线中未被检测到（7个源均未显示扩展x射线发射）。
Investigations of the cluster environment of radio sources have not shown a correlation between radio power and degree of clustering. However, it has been demonstrated that extended X-ray luminosity and galaxy clustering do exhibit a positive correlation. This study investigates a complete sample of 25 nearby (z ≤ 0.06) radio galaxies that are not cataloged members of Abell clusters. The environment of these radio galaxies is studied in both the X-ray and the optical by means of the ROSAT All-Sky Survey (RASS), ROSAT pointed observations, and the Palomar optical Digitized Sky Survey (DSS). X-ray luminosities and extents are determined from the RASS, and the DSS is used to quantify the degree of clustering via the spatial two-point correlation coefficient, Bgg. Of the 25 sources, 20 are ≥3 σ detections in the X-ray and 11 possessed Bgg's significantly in excess of that expected for an isolated galaxy. Adding the criterion that the X-ray emission be resolved, 10 of the radio galaxies do appear to reside in poor clusters with extended X-ray emission suggestive of the presence of an intracluster medium. Eight of these galaxies also possess high spatial correlation coefficients. Taken together, these data suggest that the radio galaxies reside in a low-richness extension of the Abell clusters. The unresolved X-ray emission from the other galaxies is most likely associated with active galactic nucleus phenomena. Furthermore, although the sample size is small, it appears that the environments of FR I and FR II sources differ. FR I's tend to be more frequently associated with extended X-ray emission (10 of 18), whereas FR II's are typically point sources or nondetections in the X-ray (none of the seven sources exhibit extended X-ray emission).