Ultra violet variability studies in fairall 9 Seyfert 1 galaxy using intensive monitoring observations of IUE satellite.

Active galaxies are a class of bright external galaxies emitting nearly constant "strong continuum radiation" from the unresolved compact nuclear region (r ≤ 1017 cm) and across the entire EM spectrum. IUE satellite has made intensive observations of Fairall 9, one of the brightest (∼ 13.8 mag) and low redshift (z = 0.0461) active galaxies in the year 1994. In this paper, we present our investigations on the UV variability properties strong emission lines Lyα+NV + N V and C IV, which are emitted from the broad line region (BLR) surrounding central compact accretion disc. We have estimated the amplitudes of relative variability (∼ Rmax) and Fvar parameters by fitting power-law (Fυ ∝ υα) to the continuum and multiple Gaussian profiles to Lyα+NV + N V and C IV emission lines of UV spectra of Fairall 9 corresponding to its intensive monitoring observations by IUE satellite. These investigations concentrate on emission line variability characterization, emission line ratios, their relationship with the ionizing continuum. The characteristic feature of UV spectra of AGNs is the presence of numerous strong and broad permitted and forbidden emission lines produced in different spatial regions of the "Broad Line Region" (BLR) lying much closer to the central disc. The emission line spectra enable us to identify "active galaxies" and to probe the physical conditions in BLRs. We found Rmax parameter to be 2.21 for Lyα+NV broad component, 1.68 for Lyα+NV-Narrow component and 1.95 for the total profile of Lyα+NV. The Rmax values obtained for C IV-broad, C IV-Narrow and C IV-total profile are 2.39, 1.60 and 1.52 respectively. The UV continuum flux too has exhibited the variability trend of "decreasing flux with increasing wavelength", a phenomenon observed often in most low and intermediate redshift Seyfert 1 galaxies and quasars. These findings seem to correspond with the variance of Lyα+NV and C IV lines recorded by several publications using identical IUE data. [ABSTRACT FROM AUTHOR]