标题： MCG-6-30-15中X射线铁线回波缺失：对黑洞质量和吸积盘结构的启示 显示英文标题

标题： On the lack of X-ray iron line reverberation in MCG-6-30-15: Implications for the black hole mass and accretion disk structure

摘要： 我们采用Press、Rybicki与Hewitt（1992）提出的方法，搜索MCG-6-30-15的RXTE数据中不同能段之间的时间延迟和时间提前。 我们的搜索目标是探测荧光铁Kα线的任何回声特征，据信该线源自黑洞吸积盘的内区。 本质上，我们对连续能段（2-4 keV）的光变曲线应用了一种最优重建算法，该算法可以平滑噪声并填补数据空隙。 然后，通过尝试传递函数重构的连续能段光变曲线，以寻找连续能段与铁线能段（5-7 keV）之间的延迟或提前。 我们在铁线能段发现了减少的分数变异性。 Lee等人（1999）的谱分析表明，这归因于一个显然恒定的铁线流量（至少在几个x10^4秒的时间尺度上），以及与光子指数相关的流量变化。 我们也未发现铁线回声，并排除了0.5至50 ksec范围内的回声延迟。 这扩展了Lee等人的结论，并表明铁线流量在短至0.5 ksec的时间尺度上保持恒定。 根据铁线流量的恒定性粗略推断出的大质量黑洞（>10^8太阳质量）被其他证据否定了。 我们建议MCG-6-30-15中的黑洞质量为M_BH~10^6-10^7太阳质量，并且盘面电离状态的变化可能引起令人困惑的光谱变化。 最后，发现8-15 keV能段比2-4 keV能段滞后50-100秒。 这一结果用于限制产生此AGN硬X射线幂律的康普顿化介质的大小和几何形状。 显示英文摘要

摘要： We use the method of Press, Rybicki & Hewitt (1992) to search for time lags and time leads between different energy bands of the RXTE data for MCG-6-30-15. We tailor our search in order to probe any reverberation signatures of the fluorescent iron Kalpha line that is thought to arise from the inner regions of the black hole accretion disk. In essence, an optimal reconstruction algorithm is applied to the continuum band (2-4keV) light curve which smoothes out noise and interpolates across the data gaps. The reconstructed continuum band light curve can then be folded through trial transfer functions in an attempt to find lags or leads between the continuum band and the iron line band (5-7keV). We find reduced fractional variability in the line band. The spectral analysis of Lee et al. (1999) reveals this to be due to a combination of an apparently constant iron line flux (at least on timescales of few x 10^4s), and flux correlated changes in the photon index. We also find no evidence for iron line reverberation and exclude reverberation delays in the range 0.5-50ksec. This extends the conclusions of Lee et al. and suggests that the iron line flux remains constant on timescales as short as 0.5ksec. The large black hole mass (>10^8Msun) naively suggested by the constancy of the iron line flux is rejected on other grounds. We suggest that the black hole in MCG-6-30-15 has a mass of M_BH~10^6-10^7Msun and that changes in the ionization state of the disk may produce the puzzling spectral variability. Finally, it is found that the 8-15keV band lags the 2-4keV band by 50-100s. This result is used to place constraints on the size and geometry of the Comptonizing medium responsible for the hard X-ray power-law in this AGN.