Unification of Luminous Type 1 Quasars through CIV Emission

TL;DR

This study analyzes a large quasar sample to unify understanding of their emission line properties, revealing systematic differences linked to disk and wind components, and highlighting potential errors in black hole property estimates.

Contribution

It introduces a unified framework for quasar emission line diversity based on disk+wind models and explores the implications for black hole and accretion physics.

Findings

CIV blueshift is nearly ubiquitous, with mean shifts of 810 km/s (RQ) and 360 km/s (RL).

The Baldwin Effect is present in both radio-quiet and radio-loud quasars.

RL quasars are consistent with disk-dominated emission, while BALQSOs are wind-dominated.

Abstract

Using a sample of 30,000 quasars from SDSS-DR7, we explore the range of properties exhibited by high-ionization, broad emission lines, such as CIV 1549. Specifically we investigate the anti-correlation between L_UV and emission line EQW (the Baldwin Effect) and the "blueshifting" of high-ionization emission lines. The blueshift of the CIV emission line is nearly ubiquitous, with a mean shift of 810 km/s for radio-quiet (RQ) quasars and 360 km/s for radio-loud (RL) quasars, and the Baldwin Effect is present in both RQ and RL samples. Composite spectra are constructed as a function of CIV emission line properties in attempt to reveal empirical relationships between different line species and the SED. Within a two-component disk+wind model of the broad emission line region (BELR), where the wind filters the continuum seen by the disk component, we find that RL quasars are consistent with being dominated by the disk component, while BALQSOs are consistent with being dominated by the wind component. Some RQ objects have emission line features similar to RL quasars; they may simply have insufficient black hole (BH) spin to form radio jets. Our results suggest that there could be significant systematic errors in the determination of L_bol and BH mass that make it difficult to place these findings in a more physical context. However, it is possible to classify quasars in a paradigm where the diversity of BELR parameters are due to differences in an accretion disk wind between quasars (and over time); these differences are underlain primarily by the SED, which ultimately must be tied to BH mass and accretion rate.