Emission line profiles and X-ray observations of Broad and Narrow Line Seyfert 1 Galaxies

TL;DR

This study investigates the emission line profiles and X-ray characteristics of Narrow and Broad Line Seyfert 1 galaxies to understand their central engine fueling mechanisms and Broad Line Region structure.

Contribution

It combines optical and X-ray spectroscopic data from SDSS and XMM-Newton to analyze the components of Seyfert 1 galaxies and their relation to emission line profiles.

Findings

Identified correlations between X-ray components and optical emission lines.

Compared properties of Narrow and Broad Line Seyfert 1 galaxies.

Provided insights into the structure of the Broad Emission Line Region.

Abstract

Narrow Line Seyfert 1 galaxies represent a distinct category in the larger family of Type 1 Active Galactic Nuclei. The occurrence of emission line profiles not broader than 2000 km/s, combined with luminosity estimates comparable to those of their broad line emitting analogues, suggests that some extreme property is characterizing the fueling of their central engines. Two hypotheses are more commonly considered: on the one hand, it was suggested that the peculiar features of NLS1s might be interpreted as the consequence of a nearly pole-on view over a geometrically flattened source; on the other, there are arguments favoring the interpretation of a relatively low mass black hole, accreting at very high rates. Both explanations provide advantages and drawbacks, but, in spite of the different assumed physics, they agree in identifying NLS1s as the crucial test ground for our understanding of the Broad Line Region structure and dynamics in AGN. Here we report the results obtained investigating asynchronous optical and X-ray spectroscopic observations, respectively extracted from the Sloan Digital Sky Survey and the XMM-Newton science archives, of a sample of both broad and narrow line emitting Seyfert 1 galaxies. Exploiting data collected by the different instruments carried on board XMM, we try to identify the various components which sum up in the observed broad band spectra of the two classes. We discuss the relation that thermal, non-thermal, line emission and broad band absorption components of the X-ray source show with the optical emission line profiles, as interpreted in the framework of a composite Broad Emission Line Region structural model.