The Origin and Evolution of \civ Baldwin Effect in QSOs from the Sloan Digital Sky Survey

TL;DR

This study analyzes a large quasar sample from SDSS to understand the evolution of the Baldwin Effect, revealing that SMBH mass primarily drives this phenomenon and that its slope remains consistent up to redshift 5.

Contribution

It provides the first comprehensive analysis of the Baldwin Effect's evolution over cosmic time using SDSS data, highlighting SMBH mass as the main influencing factor.

Findings

Strong correlation between extciv EW and continuum luminosity.

No significant evolution of the Baldwin Effect slope up to redshift 5.

SMBH mass is likely the primary driver of the Baldwin Effect.

Abstract

Using a large sample of 26623 quasars with redshifts in the range $1.5 \le z\le 5.1$ with \civ $\lambda$1549 \AA emission line in Fifth Data Release of the Sloan Digital Sky Survey (SDSS), we investigate the cosmological evolution of the Baldwin Effect, i.e. the relation between the equivalent width (EW) of the \civ emission line and continuum luminosity. We confirm the earlier result that there exists a strong correlation between the \civ EW and the continuum luminosity, and we find that, up to $z\approx 5$, the slope of the Baldwin Effect seems to have no effect of cosmological evolution. A sub-sample of 13960 quasars with broad \civ $\lambda$1549 \AA emission line from SDSS is used to explore the origin of the Baldwin Effect. We find that \civ EW have a strong correlation with the mass of supermassive black hole (SMBH), and a weak correlation with the Eddington ratio, $\lb/\ledd$. This suggests that the SMBH mass is probably the primary drive for the Baldwin Effect.