Properties of the narrow line Seyfert 1 galaxies revisited

TL;DR

This study revisits the properties of narrow line Seyfert 1 galaxies, revealing they have similar black hole masses and Eddington ratios to broad line Seyfert 1 galaxies when accounting for projection effects and correction factors.

Contribution

It provides new estimates of black hole masses and Eddington ratios for NLS1s, challenging previous assumptions and highlighting the importance of viewing angle and correction factors in AGN studies.

Findings

NLS1s and BLS1s have similar black hole masses and Eddington ratios.

Corrected black hole masses peak at approximately 2.0×10^7 solar masses.

A linear correlation between jet power and disk luminosity suggests accretion dominance.

Abstract

There is growing evidence to suggest that the black hole mass has been previously underestimated with the H$\beta$ line width for certain active galactic nuclei (AGN). With the assumption of the flatter rather than isotropic velocity distribution of gases in the broad-line region of AGN, we investigated the properties of narrow line Seyfert 1 (NLS1) galaxies, like the black hole mass and the Eddington ratio, and compared with broad line Seyfert 1 (BLS1) galaxies. Since gamma-rays detected in a few NLS1s which favor a smaller viewing angle in NLS1s than BLS1s, with the projection effect we estimated the relative black hole mass and Eddington ratio for NLS1s and BLS1s. The result implies that the NLS1s and BLS1s have similar black hole masses and Eddington ratios, peaked at a larger black hole mass and lower Eddington ratio for the NLS1s than thought before. Furthermore, with applying the correction factor 6 of average black hole mass as derived from the modelling of both optical and UV data in radio-loud NLS1s by Calderone et al., to the Xu et al. sample, we find that the NLS1s and BLS1s also show similar black hole masses and Eddington ratios, peaked at $2.0\times10^{7}M_{\odot}$ and 0.12 (Eddington ratio) for the NLS1s. The $M_{BH}-\sigma$ relation due to the enhanced black hole masses of NLS1s is discussed. In addition, there seems to show a linear correlation between jet power and disk luminosity for the flat spectrum radio-loud NLS1 sample, which implies an accretion dominated rather than black hole spin dominated jet.