Narrow vs. Broad line Seyfert 1 galaxies: X-ray, optical and mid-infrared AGN characteristics

TL;DR

This study compares narrow and broad line Seyfert 1 galaxies across multiple wavelengths, revealing differences in black hole mass, luminosities, and spectral trends that suggest NLS1s are younger, developing AGNs, while BLAGNs are more mature.

Contribution

It provides a multi-wavelength comparison of NLS1s and BLAGNs, highlighting spectral and evolutionary differences and proposing a developmental sequence.

Findings

BLAGNs have higher black hole masses and luminosities.

NLS1s show higher accretion rates and PAH contributions.

Spectral trends suggest NLS1s are younger, growing AGNs.

Abstract

We investigated narrow line Seyfert 1 galaxies (NLS1s) at optical, mid-infrared (MIR) and X-ray wavelengths, comparing them to the broad line active galactic nuclei (BLAGNs). We found that black hole mass, coronal line luminosities, X-ray hardness ratio and X-ray, optical and MIR luminosities are higher for the BLAGNs than for NLS1s, while policyclic aromatic hydrocarbon (PAH) contribution and the accretion rates are higher for the NLS1s. Furthermore, we found some trends among spectral parameters that NLS1s have and BLAGNs do not have. The evolution of FWHM(H$\beta$) with the luminosities of MIR and coronal lines, continuum luminosities, PAH contribution, H$\beta$ broad line luminosity, FWHM[O\,III] and EW(H$\beta$NLR), are important trends found for NLS1s. That may contribute to the insight that NLS1s are developing AGNs, growing their black holes, while their luminosities and FWHM(H$\beta$) consequently grow, and that BLAGNs are mature, larger objects of slower and/or different evolution. Black hole mass is related to PAH contribution only for NLS1s, which may suggest that PAHs are more efficiently destroyed in NLS1s.