The Kinematics Of AGN Broad Emission Line Region

It is important to explore the kinematics of broad emission line region of active galactic nuclei(AGNs).It can help us to understand the accretion processes and inner structure of AGNs and to get more accurate estimation of central black hole mass.In this thesis,we present a detailed study on the kinematics of C? broad emission line region,and its impact to the line formation and its connection to the accretion processes.Our AGN sample is composed of two subsamples,one is taken from SDSS(high-redshift sample),and the other is taken from the IUE and HST observation(low-redshift sample).We use a blueshift and asymmetry index(BAI)of C? line to indicate the outflow strength,we also measure the equivalent width(EW)and full width at half-maximum(FWHM).Our sample occupy a very large range in luminosity,BAI and EW parameter space.We confirm previous results:in high-reshift sample,C? and Mg? behave in an opposite way in the FWHM-BAI and FWHM-EW parameter spaces.It indicates that the two emission line regions have very different kinematics.We find that,in low redshift sample,the FWHMs of the two lines have a clear and positive correlation,and C? and Mg? exhibit the same trend in FWHM-EW parameter space.It means that the two lines are produced in the regions with very similar kinematics.Our further analysis shows that,as Lbol/LEdd<0.1,BAI is almost independent of Lbol/LEdd,while Lbol/LEdd>0.1,BAI increases strongly with Lbol/LEdd.Similar two-phase behavior is also found in the relation between Lbol/LEdd and FWHM(C?)/FWHM(Mg?).Interestingly,we found a weak anti-correlation between Lbol/LEdd and FWHM(C?)/FWHM(Mg?)at Lbol/LEdd<0.1,however more data are required to confirm this finding.Our study suggests that C?-based black hole mass may have large uncertainties and systematic bias.Finally,we study the well-known Baldwin effect and how the kinematics affect the line formation.Our analysis suggests that line formation may be affected by various processes.The C? EW is driven not only by Eddington ratio but also by outflow strength.