A Study of Active Galactic Nuclei in Low Surface Brightness Galaxies with Sloan Digital Sky Survey Spectroscopy

TL;DR

This study analyzes the spectral properties of low surface brightness galaxies using SDSS data, revealing that AGNs are less common in these galaxies than in normal high surface brightness galaxies, with some correlations to galaxy size and velocity dispersion.

Contribution

It provides the first reliable spectral classification of nuclear activity in LSBGs based on emission line diagnostics, and compares AGN prevalence with that in normal galaxies.

Findings

52% of LSBGs are star-forming

Lower AGN fraction in LSBGs compared to high surface brightness galaxies

Broad-line AGNs follow the M-$\sigma_\ast$ relation

Abstract

Active galactic nuclei (AGN) in low surface brightness galaxies (LSBGs) have received little attention in previous studies. In this paper, we present detailed spectral analysis of 194 LSBGs from the Impey et al. (1996) APM LSBG sample which have been observed spectroscopically by the Sloan Digital Sky Survey Data Release 5 (SDSS DR5). Our elaborate spectral analysis enables us to carry out, for the first time, reliable spectral classification of nuclear activities in LSBGs based on the standard emission line diagnostic diagrams in a rigorous way. Star-forming galaxies are common, as found in about 52% LSBGs. We find, contrary to some of the previous claims, that the fraction of galaxies containing an AGN is significantly lower than that found in nearby normal galaxies of high surface brightness. This is qualitatively in line with the finding of Impey et al. (2001). This result holds true even within each morphological type from Sa to Sc. LSBGs having larger central stellar velocity dispersions, or larger physical sizes, tend to have a higher chance to harbor an AGN. For three AGNs with broad emission lines, the black hole masses estimated from the emission lines are broadly consistent with the well known M-$\sigma_\ast$ relation established for normal galaxies and AGNs.