DIRECT MEASUREMENT OF THE X-RAY TIME-DELAY TRANSFER FUNCTION IN ACTIVE GALACTIC NUCLEI
DIRECT MEASUREMENT OF THE X-RAY TIME-DELAY TRANSFER FUNCTION IN ACTIVE GALACTIC NUCLEI
复制标题
活动星系核中X射线时滞传递函数的直接测量
DOI：
10.1088/0004-637x/760/1/73
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S. Kraemer
中科院分区：
文献类型：
--
作者：
E. Legg;L. Miller;T. Turner;M. Giustini;J. Reeves;S. Kraemer
利用窄线Seyfert I星系Ark564的新的XMM-牛顿数据以及1H0707-495和NGC4051的现有数据，研究了在附近的活动星系核(AGN)中，观测到的硬X射线光子和软X射线光子之间的时间滞后的来源。这些活动星系核具有高度可变的X射线光曲线，其中包含频繁的高发射峰值。从时间序列直接测量了峰的平均光曲线，结果表明：(1)在测量不确定度内，在所有X射线能量下，峰同时出现；(2)硬X射线能量处存在大量的超额发射尾巴，相对于主峰的时间延迟，在方舟564中尤为突出。观测(1)排除了观测到的滞后是由康普顿化时滞引起的，并不支持一个简单的在吸积盘上传播涨落的模型。观测结果(2)与来自初级X射线源几千光秒的物质的康普顿散射混响造成的时间滞后是一致的。峰值光曲线的功率谱密度和随频率变化的相位滞后与全时间序列的一致。在傅立叶分析和峰值分析中，都有证据表明方舟564时间序列具有非平稳性。在方舟564中观测到的尖锐的“负”滞后(硬光子能量的变化导致软光子能量)似乎是由硬带传递函数的形状产生的，而不是由X射线的软带反射引起的。这些结果加强了在I型活动星系核中存在X射线混响的证据，这要求这些活动星系核受到几十或数百个引力半径范围内的核周物质散射的显著影响。
The origin of the observed time lags, in nearby active galactic nuclei (AGNs), between hard and soft X-ray photons is investigated using new XMM-Newton data for the narrow-line Seyfert I galaxy Ark 564 and existing data for 1H 0707–495 and NGC 4051. These AGNs have highly variable X-ray light curves that contain frequent, high peaks of emission. The averaged light curve of the peaks is directly measured from the time series, and it is shown that (1) peaks occur at the same time, within the measurement uncertainties, at all X-ray energies, and (2) there exists a substantial tail of excess emission at hard X-ray energies, which is delayed with respect to the time of the main peak, and is particularly prominent in Ark 564. Observation (1) rules out that the observed lags are caused by Comptonization time delays and disfavors a simple model of propagating fluctuations on the accretion disk. Observation (2) is consistent with time lags caused by Compton-scattering reverberation from material a few thousand light-seconds from the primary X-ray source. The power spectral density and the frequency-dependent phase lags of the peak light curves are consistent with those of the full time series. There is evidence for non-stationarity in the Ark 564 time series in both the Fourier and peaks analyses. A sharp “negative” lag (variations at hard photon energies lead soft photon energies) observed in Ark 564 appears to be generated by the shape of the hard-band transfer function and does not arise from soft-band reflection of X-rays. These results reinforce the evidence for the existence of X-ray reverberation in type I AGN, which requires that these AGNs are significantly affected by scattering from circumnuclear material a few tens or hundreds of gravitational radii in extent.
DOI：
10.1111/j.1365-2966.2006.10871.x
发表时间：
2006-07
影响因子：
4.8
作者：
P. Arévalo;I. Papadakis;P. Uttley;I. McHardy;W. Brinkmann
通讯作者：
P. Arévalo;I. Papadakis;P. Uttley;I. McHardy;W. Brinkmann