M.Sc Thesis

M.Sc StudentBaskin Alexei
SubjectSome Constraints on the Physical Properties of the Narrow
Line and the Broad Line Regions in Active Galactic
DepartmentDepartment of Physics
Supervisor PROF. Ari Laor


We explore the origin of the luminosity dependence of the equivalent width (EW) of the broad C IV ?line in active galactic nuclei (AGN) using the Boroson & Green sample of the 87 ?Bright Quasar Survey (BQS) quasars. We confirm earlier results on the strong correlations of the CIV EW with some of the emission parameters which define the Boroson & Green Eigenvector 1, and with the optical to X-ray slope . In addition, we find a strong correlation of the C IV EW with the relative accretion rate, .

We explore the relation between the H?and C IV profiles using the same sample as above. We find the following: (1) Narrow C IV lines (FWHM < 2000 km s) are rare (~ 2% occurrence rate) compared to narrow H?lines (~ 20%). (2) In objects where H?FWHM < 4000 km s?the C IV line is broader than H, but the reverse is true when the H?FWHM > 4000 km s. (3) C IV appears to provide a significantly less accurate, and possibly biased estimate of the black hole mass in AGN, compared with H. (4) The C IV versus H?profile differences are correlated with some of the Eigenvector 1 parameters, which may be related with . (5) There are indications for dust reddening and scattering in "normal" AGN .

We also measured the [O III] /[O III] ?line ratio , and use it to determine whether density or covering factor control the large range in [O III] ?strength in AGN. We find that both the density and the covering factor appear to contribute significantly to the large range.