Continuum Reverberation Mapping of Mrk 876 over Three Years with Remote Robotic Observatories
Continuum Reverberation Mapping of Mrk 876 over Three Years with Remote Robotic Observatories
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DOI：
10.3847/1538-4357/ace342
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发表时间：
2023-07
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通讯作者：
Jake A. Miller;E. Cackett;M. Goad;K. Horne;A. Barth;E. Romero-Colmenero;M. Fausnaugh;J. Gelbord;K. Korista;H. Landt;T. Treu;H. Winkler
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作者：
Jake A. Miller;E. Cackett;M. Goad;K. Horne;A. Barth;E. Romero-Colmenero;M. Fausnaugh;J. Gelbord;K. Korista;H. Landt;T. Treu;H. Winkler
连续谱混响映射探测活动星系核 (AGN) 中光学连续谱发射区域的尺寸尺度。通过机器人天文台光学中长达 3 年的多波长光度监测，我们在 Mrk 876 上进行了连续混响映射。所有波段均显示出大振幅变化且相关性良好。光变曲线的缓慢变化显着拓宽了互相关函数 (CCF)，需要去除趋势才能稳健地恢复带间滞后。我们使用三种技术（CCF、JAVELIN 和 PyROA）测量一致的带间滞后，从 u 到 z 的滞后约为 13 天。这些滞后比圆盘自引力半径的预期半径 12 天长。正如薄盘理论所预期的那样，滞后随波长大致在 λ 4/3 之后增加，但滞后归一化大约比预期长 3 倍，正如在其他 AGN 中观察到的那样。 i 波段的滞后表明我们将其归因于变量 Hα 宽线发射。通量-通量分析显示，可变光谱遵循 f ν ∝ λ −1/3，正如圆盘所预期的那样，并且 i 波段中的过量也表明该波段中存在强可变 Hα 发射。
Continuum reverberation mapping probes the size scale of the optical continuum-emitting region in active galactic nuclei (AGN). Through 3 yr of multiwavelength photometric monitoring in the optical with robotic observatories, we perform continuum reverberation mapping on Mrk 876. All wave bands show large-amplitude variability and are well correlated. Slow variations in the light curves broaden the cross-correlation function (CCF) significantly, requiring detrending in order to robustly recover interband lags. We measure consistent interband lags using three techniques (CCF, JAVELIN, and PyROA), with a lag of around 13 days from u to z. These lags are longer than the expected radius of 12 days for the self-gravitating radius of the disk. The lags increase with wavelength roughly following λ 4/3, as would be expected from thin disk theory, but the lag normalization is approximately a factor of 3 longer than expected, as has also been observed in other AGN. The lag in the i band shows an excess that we attribute to variable Hα broad-line emission. A flux–flux analysis shows a variable spectrum that follows f ν ∝ λ −1/3, as expected for a disk, and an excess in the i band that also points to strong variable Hα emission in that band.