Implications Between The UV And Optical Fe ? Emission Line For SDSS J142052.43+525622.4

Quasars are the most luminous active galactic nuclei(AGNs),variability is a common phenomenon among AGN and QSOs,variability can appear on different timescales,from as short as hours and to several years,as usually occurs from radio to X-ray band.There are many methods to estimate the mass of the central black hole in active galactic nuclei,of which reverberation mapping is a reliable method.Based on the sample contained 849 SDSS-RM sources,we chose 0.5<z<0.7 to confirm the spectrum covers both ultraviolet Fe II and optical Fe II,the good SN-MED is also needed for better spectrum.Then we selected the objec-t SDSS J142052.43+525622.4(ra=215.218489514,dec=52.939560661,z=0.676)to research the ultraviolet Fe II and optical Fe II and look for the connections between them.The first section for our paper is the introductions of QSOs,st ructure fune-tion,color variability,properties and excitation mechanisms of Fe II emission line,reverberation mapping,SDSS-RM sample,Baldwin effect;the second sec-tion is the object selection and data analysis,spectral fitting,emission line fitting,and we also determine the system uncertainty for flux;the third section is the main result and discussion,such as variability analysis,structure function,color variability,and also compared the parameters of FWHM,Shift,EW,spectral inedx,Fe II flux,intensity ratio between ultraviolet Fe II and optical Fe II,we give correlation analysis;the last section is the conclusions and outlook.The main results can be summarized as follows:(1)For the selected source,we derived the flux system uncertainty to be approximately 10%by[O III]intensity distribution;(2)For the ultraviolet continuous spectrum,found brighter when the spec-trum become steeper(bluer),which shows the trend of "BWB";And the variability amplitude of ultraviolet continuous spectrum is larger than that of optical was found;(3)The correlation coefficient of Spearman test r=0.549 for optical/ultraviolet Fe II EW,which indica.ted that the origin of optical/ultraviolet Fe II might come from the same region;However,our comparative analysis found that the FWHM of ultraviolet and optical Fe II were inconsistent by comparing them,the corre-lation coefficient of Spearman test is-0.165;The ultraviolet FWHM is generally larger than the optical,according to virial theorem,tells that emission region of ultraviolet Fe II was inner than optical;We also compared the shift of ultraviolet and optical Fe II,showing a weak positive correlation,Spearman test correlation coefficient r=0.256,and the ultraviolet Fe II shift is generally larger than that of optical,which indicates that both ultraviolet and optical Fe II inflow,and the ultraviolet Fe II inflow is larger;(4)We use intensity ratio to estimate the column density of quasars;(5)Finally we also studied the Baldwin effect of Fe II,that,is,the relation-ship between Fe II EW and continuous spectral intensity,found that the Baldwin effect of ultraviolet was very obvious.