Multiwavelength observations of short-timescale variability in NGC 4151 .4. Analysis of multiwavelength continuum variability
Multiwavelength observations of short-timescale variability in NGC 4151 .4. Analysis of multiwavelength continuum variability
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DOI：
10.1086/177872
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发表时间：
1996-05
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影响因子：
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通讯作者：
R. Edelson;T. Alexander;D. Crenshaw;S. Kaspi;M. Malkan;B. Peterson;R. Warwick;J. Clavel;A. Filip
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文献类型：
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作者：
R. Edelson;T. Alexander;D. Crenshaw;S. Kaspi;M. Malkan;B. Peterson;R. Warwick;J. Clavel;A. Filip
第三页，见同上，第470卷，第1期，第349-63页(1996)。结合前面三篇论文的数据，分析了1993年12月监测期间Seyfert 1星系NGC4151的多波段变率和光谱能量分布。该光源接近其历史最高亮度，在X射线、紫外线和光学波长上显示出强烈的、相关的变化。中能(~1.5keV)X射线的变化最大，归一化变幅(NVA)为24%。在约100keV的软伽马射线能量下，出现了较弱的(NVA=6%)变化(与较低能量的变化不相关)。在较软的(0.1-1keV)X射线带中没有发现明显的变化。在紫外/光学波段，随着波长从1275增加到6900，NVA从9%下降到1%。这些数据没有探测到极端紫外线(1200埃到0.1千电子伏特)或硬X射线(250千电子伏特)的变化。不同波段变化之间的位相差符合零滞后，1275环与其他紫外波段的相位差上限为0.15天，1275环与1.5keV之间的相位差上限为0.3天，1275环与5125环之间的相位差上限为1sim1天。这些严格的限制比以前的多波段AGN监测活动中确定的改善了一个数量级以上。紫外线波动功率谱没有周期性的证据，而是很好地符合非常陡峭的红幂定律(ALES-2.5)
For pt.III see ibid., vol.470, no.1, p.349-63 (1996). Combines data from the three preceding papers in order to analyze the multi wave-band variability and spectral energy distribution of the Seyfert 1 galaxy NGC 4151 during the 1993 December monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium-energy (~1.5 keV) X-rays, with a normalized variability amplitude (NVA) of 24%. Weaker (NVA=6%) variations (uncorrelated with those at lower energies) were seen at soft gamma-ray energies of ~100 keV. No significant variability was seen in softer (0.1-1 keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9% to 1% as the wavelength increased from 1275 to 6900 Aring. These data do not probe extreme ultraviolet (1200 Aring to 0.1 keV) or hard X-ray (250 keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of lsim0.15 day between 1275 Aring and the other ultraviolet bands, lsim0.3 day between 1275 Aring and 1.5 keV, and lsim1 day between 1275 and 5125 Aring. These tight limits represent more than an order of magnitude improvement over those determined in previous multi-wave-band AGN monitoring campaigns. The ultraviolet fluctuation power spectra showed no evidence for periodicity, but were instead well fitted with a very steep, red power law (ales-2.5)