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X-Ray-to-radio Offset Inference from Low-count X-Ray Jets
The Astrophysical Journal Supplement Series ( IF 8.7 ) Pub Date : 2021-03-17 , DOI: 10.3847/1538-4365/abd8d7
Karthik Reddy 1 , Markos Georganopoulos 1, 2 , Eileen T. Meyer 1
Affiliation  

Observations of positional offsets between the location of X-ray and radio features in many resolved, extragalactic jets indicates that the emitting regions are not cospatial, an important piece of evidence in the debate over the origin of the X-ray emission on kiloparsec scales. The existing literature is nearly exclusively focused on jets with sufficiently deep Chandra observations to yield accurate positions for X-ray features, but most of the known X-ray jets are detected with tens of counts or fewer, making detailed morphological comparisons difficult. Here we report the detection of X-ray-to-radio positional offsets in 15 extragalactic jets from an analysis of 22 sources with low-count Chandra observations, where we utilized the Low-count Image Reconstruction Algorithm. This algorithm has allowed us to account for effects such as Poisson background fluctuations and nearby point sources which have previously made the detection of offsets difficult in shallow observations. Using this method, we find that in 55% of knots with detectable offsets, the X-rays peak upstream of the radio, questioning the applicability of one-zone models, including the IC/CMB model for explaining the X-ray emission. We also report the nondetection of two previously claimed X-ray jets. Many, but not all, of our sources follow a loose trend of increasing offset between the X-ray and radio emission, as well as a decreasing X-ray-to-radio flux ratio along the jet.



中文翻译:

来自低计数 X 射线射流的 X 射线到无线电偏移推断

对许多已解析的河外喷流中 X 射线位置和无线电特征之间的位置偏移的观察表明,发射区域不是共空间的,这是在千秒差距尺度上 X 射线发射起源争论中的重要证据。现有文献几乎完全专注于具有足够深度的钱德拉观测的喷流,以产生 X 射线特征的准确位置,但大多数已知的 X 射线喷流被检测到数十个或更少的计数,这使得详细的形态比较变得困难。在这里,我们报告了对 22 个源的低计数 Chandra 观测分析,在 15 个河外喷流中检测到 X 射线到无线电的位置偏移,其中我们使用了低计数图像重建算法。该算法使我们能够考虑泊松背景波动和附近点源等影响,这些影响以前使浅层观测中的偏移检测变得困难。使用这种方法,我们发现在 55% 的具有可检测偏移的节点中,X 射线在无线电上游达到峰值,这对单区模型的适用性提出了质疑,包括用于解释 X 射线发射的 IC/CMB 模型。我们还报告了两个先前声称的 X 射线射流未检测到的情况。我们的许多来源(但不是全部)遵循一种松散的趋势,即 X 射线和无线电发射之间的偏移量增加,以及沿射流的 X 射线与无线电通量之比减小。我们发现,在 55% 的具有可检测偏移的节中,X 射线在无线电上游达到峰值,这对单区模型的适用性提出了质疑,包括用于解释 X 射线发射的 IC/CMB 模型。我们还报告了两个先前声称的 X 射线射流未检测到的情况。我们的许多来源(但不是全部)遵循一种松散的趋势,即 X 射线和无线电发射之间的偏移量增加,以及沿射流的 X 射线与无线电通量之比减小。我们发现,在具有可检测偏移的 55% 的节中,X 射线在无线电上游达到峰值,这对单区模型的适用性提出了质疑,包括用于解释 X 射线发射的 IC/CMB 模型。我们还报告了两个先前声称的 X 射线射流未检测到的情况。我们的许多来源(但不是全部)遵循一种松散的趋势,即 X 射线和无线电发射之间的偏移量增加,以及沿射流的 X 射线与无线电通量之比减小。

更新日期:2021-03-17
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