X-ray Variability of the Seyfert 1 Markarian 335: Power Spectrum and Time Lags
X-ray Variability of the Seyfert 1 Markarian 335: Power Spectrum and Time Lags
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DOI：
10.1111/j.1365-2966.2008.13367.x
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发表时间：
2008-04
影响因子：
4.8
通讯作者：
P. Arévalo;I. McHardy;D. Southampton;UK.
中科院分区：
文献类型：
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作者：
P. Arévalo;I. McHardy;D. Southampton;UK.
为了进一步研究活动星系核与黑洞X射线双星的比较，我们研究了Seyfert 1星系Mrk 335的主要X射线光变特性。我们特别强调X射线的时间滞后，这是一个潜在的重要诊断的物理模型。从100 KS观测XMM-牛顿，我们表明，这个源的功率谱是很好地拟合弯曲幂律模型，和弯曲时间尺度Tb是精确的预测值由Tb与H？McHardy等人的线宽关系。不同能带的变化表现出与时间尺度相关的时间滞后，其中较高能带滞后于较低能带。滞后，？变化的傅立叶频率的函数，f，在光变曲线的可变性组件？f？1，但是在接近功率谱中的弯曲频率的频率处滞后中存在急剧截止。在黑洞X射线双星系统中也可以看到类似的行为。时滞的长度随着能量分离而连续增加，几乎呈对数线性关系。我们表明，只要X射线发射区的能谱向中心硬化，通过吸积流传播的波动可以产生滞后谱。
To investigate further the comparison between active galactic nuclei (AGN) and black hole X-ray binaries, we have studied the main X-ray variability properties of the Seyfert 1 galaxy Mrk 335. We put particular emphasis on the X-ray time lags, which is a potentially important diagnostic of physical models. From a 100 ks observation by XMM–Newton, we show that the power spectrum of this source is well fitted by a bending power-law model, and the bend time-scale Tb is precisely at the value predicted by the Tb versus H? linewidth relation of McHardy et al. Variations in different energy bands show time-scale-dependent time lags, where higher energy bands lag lower ones. The lag, ?, varies as a function of the Fourier frequency, f, of the variability component in the light curves as ??f?1 at low frequencies, but there is a sharp cut-off in the lags at a frequency close to the bend frequency in the power spectrum. Similar behaviour is seen in black hole X-ray binary systems. The length of the time lags increases continuously with energy separation, in an almost loglinear relation. We show that the lag spectra can be produced by fluctuations propagating through the accretion flow as long as the energy spectrum of the X-ray emitting region hardens towards the centre.