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arXiv 2109.02155astro-ph.GAastro-ph.HE
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UV/光学连续谱混响映射中的频率分辨滞后

Frequency-resolved lags in UV/optical continuum reverberation mapping

Edward M. Cackett, Abderahmen Zoghbi, Otho Ulrich

摘要:

近年来,涉及附近活动星系核高节奏紫外/光学监测活动的连续混响映射已被用来推断其吸积盘的大小。这些活动的主要结果之一是,与标准模型相比,在许多情况下,吸积盘显得太大,大了2 - 3倍。这部分可能是由于来自宽线区域(BLR)的扩散连续发射,这由巴耳末跳跃周围的过量滞后指示。标准的互相关滞后分析技术通常用于恢复峰值或质心滞后,并且不能容易地区分来自磁盘的再处理和BLR。然而,频率分辨的滞后分析,其中确定在每个傅立叶频率的滞后,有可能分离出不同尺寸尺度上的再处理。在这里,我们提出了模拟,以证明这种方法的潜力,然后应用极大似然的方法来确定在NGC 5548的频率分辨滞后。我们发现,NGC 5548的滞后一般随频率的增加而平滑地减小,并且不容易单独用吸积盘后处理来描述。标准的互相关滞后是一致的滞后频率低于0.1每天,这表明他们占主导地位的规模大于约10光天的再加工。与BLR一致的更远的再处理器与标准尺寸的吸积盘的组合比单独的更大的吸积盘与观察到的滞后更一致。

英文摘要:

In recent years, continuum reverberation mapping involving high cadence UV/optical monitoring campaigns of nearby Active Galactic Nuclei has been used to infer the size of their accretion disks. One of the main results from these campaigns has been that in many cases the accretion disks appear too large, by a factor of 2 - 3, compared to standard models. Part of this may be due to diffuse continuum emission from the broad line region (BLR), which is indicated by excess lags around the Balmer jump. Standard cross correlation lag analysis techniques are usually used to just recover the peak or centroid lag and can not easily distinguish between reprocessing from the disk and BLR. However, frequency-resolved lag analysis, where the lag is determined at each Fourier frequency, has the potential to separate out reprocessing on different size scales. Here we present simulations to demonstrate the potential of this method and then apply a maximum likelihood approach to determine frequency-resolved lags in NGC 5548. We find that the lags in NGC 5548 generally decrease smoothly with increasing frequency, and are not easily described by accretion disk reprocessing alone. The standard cross correlation lags are consistent with lags at frequencies lower than 0.1 per day, indicating they are dominated from reprocessing at size scales greater than about 10 light days. A combination of a more distant reprocessor, consistent with the BLR, along with a standard-sized accretion disk is more consistent with the observed lags than a larger disk alone.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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