几个活动星系核的测光反响映射研究  

Photometric reverberation mapping of several active galactic nuclei

作　　者：马芹春 吴学兵[1,2] MA Qinchun;WU Xue-Bing(Department of Astronomy,School of Physics,Peking University,Beijing 100871,China;Kavli Institute for Astronomy and Astrophysics,Peking University,Beijing 100871,China)

机构地区：[1]北京大学物理学院天文学系,北京100871 [2]北京大学科维理天文与天体物理研究所,北京100871

出　　处：《中国科学：物理学、力学、天文学》2023年第10期158-167,共10页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:11721303,11927804,12133001);中国载人航天工程(编号:CMS-CSST-2021-A06)资助项目。

摘　　要：活动星系核(Active Galactic Nuclei,AGN)宽发射线区的大小是计算中心黑洞质量的重要参数,通常可基于光谱反响映射测量的宽发射线辐射相对于连续谱辐射的时间延迟来得到,但需要花费中大型光学望远镜的很多时间.本文采用测光反响映射的方法,使用国家天文台兴隆观测站的60-cm望远镜观测了红移在0.03左右的六个AGN.利用宽波段V来示踪AGN的连续谱,用窄波段OIII去示踪AGN红移后的Hβ宽发射线.利用改进的ICCF方法(ICCF-Cut)去除掉窄波段的连续谱成分,试图得到与光谱反响映射接近的时间延迟结果.同时,我们也应用了JAVELIN方法计算Hβ的时间延迟.从六个AGN中最终发现有两个源可得到较好的测光反响映射结果,Mrk 335和3C 120的Hβ的时间延迟为7.8^(+8.0)_(−11.4)天和13.5^(+13.0)_(−8.8)天.应用阻尼随机行走模型去模拟AGN的光变曲线,发现较小的观测间隔是测光反响映射能否成功的一个关键因素.结合观测和模拟的结果,发现对于测光反响映射,虽然得到的结果误差很大,如果观测间隔较小(1–3 d)而且AGN有足够大的光变起伏,结合ICCF-Cut和JAVELIN方法仍然可以有效地得到AGN宽发射线的时间延迟.The broad emission line region size of active galactic nuclei(AGN)is an important parameter for calculating the mass of the central black hole.Usually,the size is measured by spectral reverberation mapping to obtain the time lag between the broad emission line and continuum radiations,but measurement using intermediate or large optical telescopes is timeconsuming.Here,we adopt another method to perform photometric reverberation mapping.We used a 60-cm telescope at the Xinglong station of the National Astronomical Observatories of China(NAOC)to observe six AGNs at redshift z≃0.3.We used the V broad band to trace the continuum and the narrow OIII band to trace the redshifted Hβemission line.To eliminate the influence of the continuum in the OIII band,we assumed that the continuum flux in the narrow band is equal to a fixed fractionαof the flux in the continuum band for each AGN.Under this assumption,we subtracted the continuum band flux with the ratioαfrom the narrow-band flux and obtained the light curve of the Hβline via the improved interpolated cross-correlation function(ICCF)method(ICCF-Cut).The extracted Hβlight curves were compared with the lagged continuum band light curves.We also used another method JAVELIN to calculate the Hβtime lags.The Hβtime lags obtained from the ICCF-Cut and JAVELIN were consistent with the results of spectroscopic reverberation mapping for two AGNs(Mrk 335 and 3C 120).The Hβtime lags obtained from ICCF-Cut were 7.8^(+8.0)_(−11.4) and 13.5^(+13.0)_(−8.8) d.To explain why only two of the six AGNs had good results,we used the damped random walk(DRW)model to simulate the light curves of AGNs and found that the photometric reverberation mapping required sufficient observations with high cadence.The observation and simulation results revealed that combining the ICCF-Cut and JAVELIN results may enable us to obtain reliable emission line lags for AGNs with large variability and high cadence,although the errors of lags are large.

关 键 词：活动星系核 超大质量黑洞 测光 反响映射 

分 类 号：P157.6[天文地球—天文学]