Correcting the Contamination of Second-order Spectra:Improving HαMeasurements in Reverberation Mapping Campaigns  

作　　者：Wen-Zhe Xi Kai-Xing Lu Hai-Cheng Feng Sha-Sha Li Jin-Ming Bai Rui-Lei Zhou Hong-Tao Liu Jian-Guo Wang 

机构地区：[1]Yunnan Observatories,Chinese Academy of Sciences,Kunming 650011,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Key Laboratory for the Structure and Evolution of Celestial Objects,Chinese Academy of Sciences,Kunming 650011,China [4]CAS Key Laboratory of FAST,National FAST,National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Research in Astronomy and Astrophysics》2023年第12期242-251,共10页天文和天体物理学研究（英文版）

基　　金：funded by the National Key R&D Program of China with No.2021YFA1600404;the National Natural Science Foundation of China(NSFC;grant Nos.11991051,12303022,12373018,12203096,12103041,12073068);Yunnan Fundamental Research Projects(grant Nos.202301AT070339,202301AT070358);Yunnan Postdoctoral Foundation Funding Project,the Yunnan Province Foundation(202001AT070069);the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2022058);the Topnotch Young Talents Program of Yunnan Province,Special Research Assistant Funding Project of Chinese Academy of Sciences;the science research grants from the China Manned Space Project with No.CMS-CSST-2021-A06;Funding for the telescope has been provided by the Chinese Academy of Sciences and the People’s Government of Yunnan Province。

摘　　要：Long-term spectroscopic monitoring campaigns on active galactic nuclei(AGNs)provide a wealth of information about its interior structure and kinematics.However,a number of the observations suffer from the contamination of second-order spectra(SOS)which will introduce some undesirable uncertainties at the red side of the spectra.In this paper,we test the effect of SOS and propose a method to correct it in the time domain spectroscopic data using the simultaneously observed comparison stars.Based on the reverberation mapping(RM)data of NGC 5548 in2019,one of the most intensively monitored AGNs by the Lijiang 2.4 m telescope,we find that the scientific object,comparison star,and spectrophotometric standard star can jointly introduce up to~30%SOS for Grism 14.This irregular but smooth SOS significantly affects the flux density and profile of the emission line,while having little effect on the light curve.After applying our method to each spectrum,we find that the SOS can be corrected effectively.The deviation between corrected and intrinsic spectra is~2%,and the impact of SOS on time lag is very minor.This method makes it possible to obtain the HαRM measurements from archival data provided that the spectral shape of the AGN under investigation does not have a large change.

关 键 词：techniques spectroscopic-methods data analysis-galaxies individual(NGC 5548)-(galaxies:)quasars emission lines 

分 类 号：P157.6[天文地球—天文学]