Leah Simon

Metallicity and Far-Infrared Luminosity of High Redshift Quasars

We present the results of an exploratory study of broad-line region (BLR) metallicity in 34 2.2 ≤ z ≤ 4.6 quasars with far-infrared (FIR) luminosities (L FIR ) from 10 13.4 to ≤10 12.1 L⊙. Quasar samples sorted by L FIR might represent an evolutionary sequence if the star formation rates (SFRs) in quasar hosts generally diminish across quasar lifetimes. We use rest-frame ultraviolet spectra from the Sloan Digital Sky Survey to construct three composite spectra sorted by L FI R, corresponding to average SFRs of 4980, 2130 and ≤ 340 M⊙ yr -1 after correcting for a nominal quasar FIR contribution. The measured N V λ1240/C IV λ 1550and Si IV λ 1397 +O IV] λ 1402/C IV λ 1550 emission line ratios indicate supersolar BLR metallicities in all three composites, with no evidence for a trend with the star formation rate. The formal derived metallicities, Z ∼ 5-9Z⊙, are similar to those derived for the BLRs of other quasars at similar redshifts and luminosities. These results suggest that the ongoing star formation in the host is not responsible for the metal enrichment of the BLR gas. Instead, the BLR gas must have been enriched before the visible quasar phase. These results for high quasar metallicities, regardless of L FIR , are consistent with evolution scenarios wherein visibly bright quasars appear after the main episode(s) of star formation and metal enrichment in the host galaxies. Finally, young quasars, those more closely associated with a recent merger or a blowout of gas and dust, may exhibit tracers of these events, such as redder continuum slopes and higher incidence of narrow absorption lines. With the caveat of small sample sizes, we find no relation between L FIR and the reddening or the incidence of absorption lines.

The origins of a rich absorption line complex in a quasar at redshift 3.45

We discuss the nature and origin of a rich complex of narrow absorption lines in the quasar J 102325.31 +514251.0 at redshift 3.447. We measure nine C IV(λλ 1548, 1551 ) absorption line systems with velocities from -1400 to -6200 km s -1 , and full widths at half-minimum ranging from 16 to 350 kms -1 . We also detect other absorption lines in these systems, including H C III , N v, O VI and Si IV. Lower ionization lines are not present, indicating a generally high degree of ionization in all nine systems. The total hydrogen column densities range from ≲ 10 17.2 to 10 19.1 cm -2 . The tight grouping of these lines in the quasar spectrum suggests that most or all of the absorbing regions are physically related. We examine several diagnostics to estimate more directly the location and origin of each absorber. Four of the systems can be attributed to a quasar-driven outflow based on line profiles that are smooth and broad compared to thermal linewidths and to the typical absorption lines formed in intergalactic gas or galaxy haloes. Several systems also have other indicators of a quasar outflow origin, including partial covering of the quasar emission source (e.g. in systems with speeds too high for a starburst-driven flow), O vi column densities above 10 15 cm -2 and an apparent line-lock in C IV (in two of the narrow profile systems). A search for line variability yielded null results, although with very poor constraints because the comparison spectra have much lower resolution. Altogether (but not including the tentative line-lock) there is direct evidence for six of the nine systems forming in a quasar outflow. Consistent with a near-quasar origin, eight of the systems have metallicity values or lower limits in the range Z ≥ 1-8 Z ⊙ . The lowest velocity system, which has an ambiguous location based on the diagnostics mentioned above, also has the lowest metallicity, Z ≤ 0.3Z ⊙ , and might form in a non-outflow environment farther from the quasar. Overall, however, this complex of narrow absorption lines can be identified with a highly structured, multicomponent outflow from the quasar. The high metallicities are similar to those derived for other quasars at similar redshifts and luminosities, and are consistent with evolution scenarios wherein quasars appear after the main episodes of star formation and metal enrichment in the host galaxies.

Quasar Metal Abundances & Host Galaxy Evolution

Quasars signal a unique phase of galaxy evolution – when massive spheroids are rapidly being assembled, forming stars and growing their central super-massive black holes. Measurements of the metal abundances around quasars provide unique information about these complex evolutionary processes. Here we provide a brief review of the current status and implications of quasar abundance research. The central goal of quasar abundance studies is to understand the evolutionary relationship between quasars, super-massive black holes (SMBHs) and their host galaxies. We know that a close relationship exists because dormant SMBHs are not only common in galactic nuclei today, but their masses, M BH , scale directly with the mass of the surrounding galactic spheroids, M gal , (e.g., Tremaine et al. 2002). Whatever processes created the galactic spheroids must have also (somehow) created central SMBHs with commensurate mass. Luminous quasars represent the final major growth stage(s) of the most massive SMBHs inside the most massive galaxies. The quasar phase is very brief, of order 10 8 yr, but it coincides with a critical stage of SMBH–galaxy evolution when galactic spheroids are still rapidly being assembled and making stars. The energy output from accreting black holes might, in fact, regulate that star formation and thus lead naturally to the observed M BH – M gal correlation (Kauffmann & Haehnelt 2000, Granato et al. 2004). Quasar abundance studies can help us understand better the complex evolutionary relationship between SMBHs and their host galaxies. For example, how much star formation (how much conversion of the initial gas into stars) occurs in galactic spheroids before the visible quasar epoch? Did the major star-forming episodes occur before, during or after the final luminous stages of SMBH growth? Is the relative timing of these events consistent with quasars triggering star formation, shutting it down, or having no affect at all? How much do outflows during the quasar epoch contribute to the distribution of metals to the 1

The gaseous environments of quasars: associate absorption lines with density and distance constraints

Associated absorption lines (AALs) in quasar spectra are valuable probes of the gas kinematics and physical conditions in quasar environments. The host galaxies are by definition in an active evolution stage that might involve large-scale blowouts and/or cold-mode accretion (infall) from the intergalactic medium (IGM). We discuss rest-frame UV spectra of four redshift 2-3 quasars selected to have low-ionisation AALs of SiII or CII that place unique density and distance constraints on the absorbers. Our analysis of the AALs yields the following results. One of the quasars, Q0119

Tracing Outflows in High-Redshift Quasars

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Narrow UV Absorption Line Outflows from Quasars

046, has a rich complex of 11 AAL systems that appear to be infalling at measured speeds from

A Census of Narrow C IV Absorption Lines in 24 Quasars at Redshifts 1.9 < z < 4.6

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Metallicities and Outflows in High Redshift Quasars

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Tracing Metallicity in High Redshift Quasars

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The Influence of Black Hole Growth on Star Formation at High Redshift

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