Correlation Analysis of a Large Sample of Narrow-Line Seyfert 1 Galaxies: Linking Central Engine and Host Properties

TL;DR

This study statistically analyzes a large sample of NLS1 galaxies to identify key factors linking the central engine properties with host galaxy characteristics, highlighting the role of ISM density and accretion processes.

Contribution

It establishes the importance of narrow-line region density in Eigenvector 1 space, linking central engine properties with host galaxy ISM, a novel insight in AGN studies.

Findings

Narrow-line region density is as important as Eddington ratio in Eigenvector 1.

Confirmed correlations between Hbeta line width, FeII, and [OIII] emission lines.

Large-scale environments of NLS1 and BLS1 galaxies are similar.

Abstract

We present a statistical study of a large, homogeneously analyzed sample of narrow-line Seyfert 1 (NLS1) galaxies, accompanied by a comparison sample of broad-line Seyfert 1 (BLS1) galaxies. Optical emission-line and continuum properties are subjected to correlation analyses, in order to identify the main drivers of active galactic nuclei (AGN) correlation space, and of NLS1 galaxies in particular. For the first time, we have established the density of the narrow-line region as a key parameter in Eigenvector 1 space, as important as the Eddington ratio L/Ledd. This is important because it links the properties of the central engine with the properties of the host galaxy; i.e., the interstellar medium (ISM). We also confirm previously found correlations involving the line width of Hbeta, and the strength of the FeII and [OIII]5007 emission lines, and we confirm the important role played by L/Ledd in driving the properties of NLS1 galaxies. A spatial correlation analysis shows that large-scale environments of the BLS1 and NLS1 galaxies of our sample are similar. If mergers are rare in our sample, accretion-driven winds on the one hand, or bar-driven inflows on the other hand, may account for the strong dependence of Eigenvector 1 on ISM density.