用可变双部分覆盖模型解释1H 0707 -495的X射线光谱变化
Interpretation of the X-ray Spectral Variation of 1H0707-495 with a Variable Double Partial Covering Model
摘要：
窄线塞弗特1星系1H 0707 -495被认为具有显著的X射线光谱变化。它的X射线能谱的特征在于强的软过量发射，在~7 keV处的极深的铁K边缘结构，以及在~1 keV处的推定的铁L线/边缘特征。发现1H 0707 -495在0.5-10 keV的能谱可用“可变双部分覆盖模型”成功地解释，即由软多色盘黑体分量和硬幂律分量组成的连续谱被两个电离态不同、部分覆盖率相同的电离吸收层部分覆盖。较低电离和较厚的吸收层主要解释了铁的K边特征，较高电离和较薄的吸收层解释了L边特征。我们已经发现，观测到的显着的强度/光谱变化在~天内主要是由部分覆盖分数的变化来解释。在我们的模型中，内禀光度和光谱形状在~天内几乎不变，而在3 keV以上的一些内禀变化是公认的。这与多色盘黑体光谱在该时间尺度上几乎不变，而硬幂律分量变化较大的情况相一致。我们认为1H 0707 -495的光谱变化是由三种不同时间尺度的物理独立变化引起的：（1）内在光度随时间的变化，（2）部分覆盖分数在小时的时间尺度上的变化，以及（3）在小时或更短的时间尺度上超过3 keV的小内在硬成分变化。
英文摘要：
The Narrow-line Seyfert 1 galaxy 1H0707-495 is known to exhibit significant X-ray spectral variations. Its X-ray energy spectrum is characterized by a strong soft excess emission, an extremely deep iron K-edge structure at ~7 keV, and a putative iron L-line/edge feature at ~1 keV. We have found that the energy spectrum of 1H0707-495 in 0.5-10 keV is successfully explained by a "variable double partial covering model" where the original continuum spectrum, which is composed of the soft multi-color disk blackbody component and the hard power-law component, is partially covered by two ionized absorption layers with different ionization states and the same partial covering fraction. The lower-ionized and thicker absorption layer primarily explains the iron K-edge feature, and the higher-ionized and thinner absorption layer explains the L-edge feature. We have discovered that the observed significant intensity/spectral variation within a ~ day is mostly explained by only variation of the partial covering fraction. In our model, the intrinsic luminosity and spectral shape are hardly variable within a ~ day, while some intrinsic variability above 3 keV is recognized. This is consistent with the picture that the multi-color disk blackbody spectrum is almost invariable in this timescale, and the hard power-law component is more variable. We propose that the observed spectral variation of 1H0707-495 is caused by three physically independent variations with different timescales; (1) intrinsic luminosity variation over days, (2) variation of partial covering fraction at a timescale of hours, and (3) small intrinsic hard component variation above 3 keV in a timescale of hours or less.
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