Properties of the Narrow Line Seyfert 1 Galaxies Revisited

Xiang Liu,Zhen Zhang,Renzhi Supriyanto,Pingping Yang

doi:10.4236/ijaa.2016.62014

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.

Highlights

Since the detection of GeV gamma-ray emission in some of narrow line Seyfert 1 (NLS1) galaxies with theHow to cite this paper: Liu, X., Yang, P.P., Su, R.Z. and Zhang, Z. (2016) Properties of the Narrow Line Seyfert 1 Galaxies Revisited
The black hole mass at the center of NLS1s is usually estimated using the velocity of H β which is assumed to be the virial velocity of the Broad Line Region (BLR) clouds, e.g. in [11] [18], but as noted in the previous section the black hole mass measured with the H β for NLS1s is most likely underestimated, because the observed FWHM of the H β is dependent on the orientation of the line of sight to the gas of BLR
The orientation angle could be correlated with the spectral index or radio core dominance for radio-loud NLS1s, it is found that the FWHM of H β correlates significantly with radio core dominance and biases black hole mass determinations that use it, but that this is not the case for velocity dispersion σ based on [O III] λ5007, by comparing the black hole mass estimated using H β and [OIII] λ5007 which tracks mass via the Mbh − σ relation [39]

Summary

Introduction

Since the detection of GeV gamma-ray emission in some of narrow line Seyfert 1 (NLS1) galaxies with the. (2016) Properties of the Narrow Line Seyfert 1 Galaxies Revisited. The “narrow line Seyfert 1” was first denoted by Osterbrock and Pogge [1], who found that the NLS1s had properties that different to normal Seyfert 1 galaxies, as quantified by Goodrich [2]: 1) unusually narrower HI lines, i.e. the Balmer lines are only slightly broader than forbidden lines such as [O III], [N II] and [S II], with a quantified criterion of FWHM ( H β ) < 2000 km/s; 2) the line ratio [OIII ]λ5007 H β < 3 , a level found discriminated well between. We intend to revisit the properties of NLS1s with the flat BLR model and new findings of black hole mass in this paper

The “Flat” BLR of AGN and Its Implications

BH Mass and Eddington Ratio of NLS1s

Density of Narrow-Line Region and γ-Rays

Findings

Discussion and Summary