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首页> 外文期刊>The Astrophysical journal >Chandra Observations of the Narrow-Line Seyfert 1 Galaxy RX J2217.9?5941
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Chandra Observations of the Narrow-Line Seyfert 1 Galaxy RX J2217.9?5941

机译:窄线赛弗1星系RX J2217.9?5941的Chandra观测

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We report the results of two Chandra ACIS-S observations from 2003 February and August of the highly X-ray variable narrow-line Seyfert 1 galaxy RX J2217.9-5941. Observations spanning the time from the ROSAT All-Sky Survey (RASS) through an ASCA observation in 1998 indicate apparently monotonically decreasing flux by a factor of 30. The Chandra observations reveal increased emission over that seen with ASCA, supporting a persistent variability rather than an X-ray outburst event. However, the cause of the strong X-ray variability remains unclear. Our Chandra observations confirm the steep soft X-ray spectrum in the 0.2–2.0 keV band found during the RASS observation (αX = 2.7). The spectral shape of the source appears to be variable, with the spectrum becoming softer when the source becomes fainter. Best-fitting models to the data include an absorbed broken power law, a blackbody plus a power law, and a power law with partial covering absorption. The latter model suggests a variable partial covering absorber in the line of sight, which can explain in part the variability seen in RX J2217.9-5941. We suggest that there might be a population of narrow-line Seyfert 1 galaxies that are, at least at times, highly absorbed.
机译:我们报告了从2003年2月和8月开始的两个Chandra ACIS-S观测结果,这些观测结果是高度X射线可变窄线塞弗1星系RX J2217.9-5941。从ROSAT全天空调查(RASS)到1998年进行ASCA观测的时间跨度的观测表明,通量明显单调减少了30倍。钱德拉观测表明,与ASCA相比,排放量增加了,这支持了持续的可变性而不是持续的变化。 X射线爆发事件。但是,尚不清楚X射线变异性强的原因。我们的Chandra观测结果证实了在RASS观测中发现的0.2–2.0 keV频带内陡峭的软X射线光谱(αX= 2.7)。光源的光谱形状似乎是可变的,当光源变暗时,光谱会变得更柔和。数据的最佳拟合模型包括吸收的破碎幂定律,黑体加幂定律以及部分覆盖吸收的幂定律。后一种模型建议在视线范围内使用可变的部分覆盖吸收体,这可以部分解释RX J2217.9-5941中的变化。我们建议可能存在至少有时被高度吸收的窄线塞弗特1星系。

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