Elemental abundances in the broad emission line region of quasars at redshifts larger than 4

Abstract

Abstract. We present observations of 11 high redshift quasars (3.9 < ∼ z < ∼ 5.0) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination ultraviolet emission lines are measured to estimate the chemical composition of the line emitting gas. Comparisons to photoionization calculations indicate gas metallicities in the broad emission line region in the range of solar to several times solar. The average of the mean metallicity of each high-z quasar in this sample is Z/Z = 4.3 ± 0.3. Assuming a chemical evolution time scale of τ evol 0.5 − 0.8 Gyrs, we derive a redshift of z f 6 to 8 for the onset of the first major star formation episode (H 0 = 65 km s −1 Mpc −1 , Ω M = 0.3, Ω Λ = 0.7), corresponding to an age of the universe of several 10 8 yrs at this epoch. We note that this epoch is also supposed to be the era of re-ionization of the universe.

A Relation between Supermassive Black Hole Mass and Quasar Metallicity?

“…Quasars at high redshifts are signposts of the last stages in the formation of these massive SMBHs in the cores of young galactic spheroids. The high metallicities near these objects reported here and elsewhere Dietrich et al 1999Dietrich et al , 2003aDietrich et al , 2003bHamann 1997;Hamann et al 2002;Osmer et al 1994;Petitjean et al 1994;Warner et al 2002) imply that the gas has already (at the quasar epoch) been substantially processed/enriched by multiple generations of massive stars. This rapid evolution at high redshifts, however, is well within the parameters derived in some recent simulations, which show that the densest protogalactic condensations can form stars and reach solar or higher metallicities at ze6 (Gnedin & Ostriker 1997;Haiman & Loeb 2001).…”

“…They find a lack of a Baldwin effect for N v, which in the present study leads to emission-line ratios involving N v increasing with increasing luminosity. However, Dietrich et al (2003aDietrich et al ( , 2003b find that metallicities derived from ratios involving both N iii] and N v are solar or greater, for samples of 70 high-redshift (3:9dzd5:0) quasars.…”

“…Moreover, the most homogeneous and therefore most reliable H ii region data (Pilyugin et al 2002;Pettini et al 2002) indicate that the scatter in N/O decreases and the validity of N=O / O=H improves in the regime of roughly solar or higher metallicities. This is the regime of the gas near quasars, based on studies of both their broad emission and intrinsic narrow absorption lines Dietrich et al 1999Dietrich et al , 2003aHamann 1997;Hamann et al 2002;Osmer, Porter, & Green 1994;Petitjean, Rauch, & Carswell 1994;Warner et al 2002). In this paper, we simply assume that N=O / O=H applies.…”

Photoionized $\ion{O}{vi}$ absorbers toward the bright QSO HE 0515–4414

“…4.1, such high over solar abundances are usually observed in quasar broad emission line regions. For example, the metallicity of Z ∼ 2 Z was measured in the z em = 4.16 QSO BR 2248-1248 (Warner et al 2002) and the metallicities of Z ∼ 4 Z were detected in the spectra of 11 high redshift QSOs (3.9 < ∼ z < ∼ 5.0) by Dietrich et al (2003).…”

Bal Phosphorus Abundance and Evidence for Immense Ionic Column Densities in Quasar Outflows: VLT/X-Shooter Observations of Quasar SDSS J1512+1119

“…Early abundance studies in BAL outflows implied particularly high abundances of heavy elements relative to hydrogen. In several cases, enhancement of carbon, nitrogen, oxygen, and silicon by factors of tens to hundreds of times the solar values were reported in several objects (e.g., Turnshek 1986;Turnshek et al 1996;Hamann 1998), in contrast to the order of magnitude or less, generally derived from the analysis of the quasar emission lines (e.g., Hamann & Ferland 1993;Hamann et al 2002;Dietrich et al 2003;Juarez et al 2009). …”