Is there a connection between Broad Absorption Line Quasars and Narrow Line Seyfert 1 galaxies?

TL;DR

This study compares Broad Absorption Line Quasars and Narrow Line Seyfert 1 galaxies, revealing similarities in accretion rates and spectral properties, but differences in black hole mass and development stage.

Contribution

It provides the first detailed comparison of BAL QSOs and NLS1s using spectral analysis and principal component analysis, highlighting their similarities and differences.

Findings

BAL QSOs and NLS1s both operate at high Eddington ratios.

BAL QSOs have significantly larger black hole masses than NLS1s.

Extreme accretion rates in some BAL QSOs suggest relativistic black hole spin.

Abstract

We consider whether Broad Absorption Line Quasars (BAL QSOs) and Narrow Line Seyfert 1 galaxies (NLS1s) are similar, as suggested by Brandt & Gallagher (2000) and Boroson (2002). For this purpose we constructed a sample of 11 BAL QSOs from existing Chandra and Swift observations. We found that BAL QSOs and NLS1s both operate at high Eddington ratios L/Ledd, although BAL QSOs have slightly lower L/Ledd. BAL QSOs and NLS1s in general have high FeII/H$\beta$ and low [OIII]/H$\beta$ ratios following the classic 'Boroson \& Green' eigenvector 1 relation. We also found that the mass accretion rates $\dot{M}$ of BAL QSOs and NLS1s are more similar than previously thought, although some BAL QSOs exhibit extreme mass accretion rates of more than 10 \msun/year. These extreme mass accretion rates may suggest that the black holes in BAL QSOs are relativistically spinning. Black hole masses in BAL QSOs are a factor of 100 larger than NLS1s. From their location on a M-$\sigma$ plot, we find that BAL QSOs contain fully developed black holes. Applying a principal component analysis to our sample we find eigenvector 1 to correspond to the Eddington ratio L/Ledd, and eigenvector 2 to black hole mass.