Optical and X-Ray Observations of MAXI J1820+070 During the Early Outburst Phase in 2018:Zooming in the Low Frequency QPOs  

作　　者：Dong-Ming Mao Wen-Fei Yu Ju-Jia Zhang Zhen Yan Stefano Rapisarda Xiao-Feng Wang Jin-Ming Bai 

机构地区：[1]Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Yunnan Observatories,Chinese Academy of Sciences,Kunming 650011,China [4]Key Laboratory for the Structure and Evolution of Celestial Objects,CAS,Kunming 650216,China [5]Physics Department,Tsinghua University,Beijing 100084,China [6]Beijing Planetarium,Beijing Academy of Sciences and Technology,Beijing 100044,China

出　　处：《Research in Astronomy and Astrophysics》2022年第4期106-113,共8页天文和天体物理学研究（英文版）

基　　金：Supported by the National Natural Science Foundation of China。

摘　　要：We report a further investigation of the optical low frequency quasi periodic oscillations(LF QPOs)detected in the black hole transient MAXI J1820+070 in the 2018 observations with the YFOSC mounted on Lijiang 2.4 m telescope(LJT).In addition,we make use of the Insight-HXMT/HE observations to measure the properties of the quasi-simultaneous X-ray LF QPOs of MAXI J1820+070 on the same day.We compared the centroid frequency,the full width at half maximum(FWHM)and the fractional rms of the LF QPOs in both wavelength ranges.We found that the centroid frequency of the optical QPO is at a frequency of 51.58 m Hz,which is consistent with that of the X-ray LF QPO detected on the same day within 1 m Hz.We also found that the FWHM of the optical LF QPO is significantly smaller than that of the X-ray LF QPO,indicating that the optical QPO has a higher coherence.The quasi-simultaneous optical and the X-ray LF QPO at a centroid frequency of about 52 m Hz suggests that the actual mechanisms of these LF QPOs as the Lense-Thirring precession should work in the vicinity of a radius of about 80-117 gravitational radii(R_(g)=GM/c^(2),M is the mass of the black hole)from the black hole if the QPO frequency is related to a proxy of the orbital frequency in the accretion fiow as the Lense-Thirring precession model suggests.Furthermore,the apparent higher coherence of the optical QPO favors that it is a more original signal as compared with the X-ray QPO.

关 键 词：X-ray stars Low mass binary stars X-ray transient sources 

分 类 号：P15[天文地球—天文学]