Active galaxies are most luminous objects in the universe whose spectra are characterized by both permitted and forbidden emission line features. The spectra of Seyfert 1 galaxies and quasars contain strong and broad emission lines of wide ranging ionization potentials. The velocity widths of the lines range from a minimum of ≈ 500 km/s for narrow lines to a maximum of 20,000 km/sec for broad lines. The UV spectra of the active galaxies contain strong and broad emission lines such as Lyα, NV, SiIV, OIV], CIV, CIII] and MgII lines. The widths of the broad lines are attributed to the differential doppler shifts of the emission lines due to the bulk motions of individual clumpy gas clouds in the BLR region. We have anlysed UV spectra of Seyfert 1 galaxies and quasars from IUE satellite archival database to understand the nature of dependence of the emission line properties with the underlying UV continuum. We have undertaken line luminosity correlation studies for Lyα and CIV lines with their underlying UV continuum luminosity at 1125Å, 1425Å & 1625Å. The IUE archival spectra have been reduced for galactic reddening using the E(B-V) and NHI values published continuum luminosity has been observed at 1125Å, 1425Å & 1625Å. The Lyα line line has exhibited strongest linear correlation wavelengths while CIV line has shown at 1425Å and 2625Å wavelengths. These results are empirically consistent with the predictions of the general multi-component photo-ionization models suggesting that the central strong UV continuum has been reprocessed by the clumpy gas clouds of the broad emission region (BLR). A detailed account of the data reduction, UV flux measurement and the significance of line-luminosity correlations are discussed in this paper.

Active galaxies are the most luminous objects observed in the Universe and are believed to be powered by mass accretion processes taking place in the vicinity of the central Super massive black hole (MBH ≥ 108Msun). However, the details of the power generation mechanisms are not understood well yet. In this paper, we are presenting a comparative study of luminosity-distance estimations for the complete sample of active galaxies observed by IUE satellite by different methods. IUE has made UV spectroscopic observations of nearly 400 active galaxies comprising mostly Seyfert 1 galaxies and quasars. We have chosen all the active galaxies observed by IUE satellite for the study of luminosity-distance with redshift. The luminosity-distances (DL) have been calculated using the Hubbles law under non-relativistic and relativistic limits with H0 = 73 Km/sec/Mpc and Terrell (1979) also. We have found that all DL estimations are consistent with each other for z ≤ 1 and diverge for z ≥ 1. The results of cosmological calulator I and II are found to consistent with each other and higher by several factors over cosmological calculator IV and the predictions of the Hubble's law under relativistic case. We observe a kind bimodal distributions in DL for z ≤ 3.5.

The Lyα and the C IV line profiles in the spectra of quasars and Seyfert 1 galaxies can be described by a combination of a narrow and a broad component. Over four orders of magnitude in luminosity the profiles of Lyα and C IV lines in the quasar spectra are very similar but a change is observed in the C IV profile in the spectra of Seyfert 1 galaxies which cover a smaller luminosity range. The correlation of the FWHM of Lyα, C IV and Hβ lines suggests that the Lyα and C IV lines are emitted from clouds in a similar kinematic enviornment but part of C IV line may also be emitted from clouds which emit the Hβ line.