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We have investigated the strength of ultraviolet Fe II emission from quasars within the environments of Large Quasar Groups (LQGs) in comparison with quasars elsewhere, for 1.1 <= <z_LQG> <= 1.7, using the DR7QSO catalogue of the Sloan Digital Sky Survey. We use the Weymann et al. W2400 equivalent width, defined between the rest-frame continuum-windows 2240-2255 and 2665-2695 Ang., as the measure of the UV Fe II emission. We find a significant shift of the W2400 distribution to higher values for quasars within LQGs, predominantly for those LQGs with 1.1 <= <z_LQG> <= 1.5. There is a tentative indication that the shift to higher values increases with the quasar i magnitude. We find evidence that within LQGs the ultrastrong emitters with W2400 >= 45 Ang. (more precisely, ultrastrong-plus with W2400 >= 44 Ang.) have preferred nearest-neighbour separations of ~ 30-50 Mpc to the adjacent quasar of any W2400 strength. No such effect is seen for the ultrastrong emitters that are not in LQGs. The possibilities for increasing the strength of the Fe II emission appear to be iron abundance, Ly-alpha fluorescence, and microturbulence, and probably all of these operate. The dense environment of the LQGs may have led to an increased rate of star formation and an enhanced abundance of iron in the nuclei of galaxies. Similarly the dense environment may have led to more active blackholes and increased Ly-alpha fluorescence. The preferred nearest-neighbour separation for the stronger emitters would appear to suggest a dynamical component, such as microturbulence. In one particular LQG, the Huge-LQG (the largest structure known in the early universe), six of the seven strongest emitters very obviously form three pairings within the total of 73 members.
We present spectra of six luminous quasars at z ~ 2, covering rest wavelengths 1600-3200 A. The fluxes of the UV Fe II emission lines and Mg II 2798 doublet, the line widths of Mg II, and the 3000 A luminosity were obtained from the spectra. These qu
We investigate the strength of ultraviolet Fe II emission in fainter quasars compared with brighter quasars for 1.0 <= z <= 1.8, using the SDSS (Sloan Digital Sky Survey) DR7QSO catalogue and spectra of Schneider et al., and the SFQS (SDSS Faint Quas
The enrichment of Fe, relative to alpha-elements such as O and Mg, represents a potential means to determine the age of quasars and probe the galaxy formation epoch. To explore how ion{Fe}{2} emission in quasars is linked to physical conditions and
The observed line intensity ratios of the Si II 1263 and 1307 AA multiplets to that of Si II 1814,AA in the broad line region of quasars are both an order of magnitude larger than the theoretical values. This was first pointed out by Baldwin et al. (
The M82 galaxy has been the subject of several studies basically because it is relatively close to to the Milky Way and it displays a strong star formation activity. Using multi-band images of M82 we have determined the age and extinction of the stel