Active Dwarf Galaxy Database II: Connections between Host Galaxy Properties and Black Hole Accretion Signatures

TL;DR

We address biases in multi-wavelength selection of active dwarf galaxies and connect AGN signatures to host properties using a uniform reanalysis of the ADGD. The study employs SED modeling with X-CIGALE and t-SNE clustering to derive host-galaxy parameters and to group galaxies by their AGN sub-populations. Key findings include infrared-color-selected AGN having the highest star formation rates and lowest stellar masses, broad-line AGN showing significantly higher AGN luminosities, and X-ray/variability-selected AGN showing elevated star formation rates compared to optical narrow-line selections. The results suggest distinct accretion epochs or evolutionary stages, and provide constraints on the co-evolution of black holes and dwarf hosts in a multi-wavelength context.

Abstract

We investigate the connection between accretion signatures and host galaxy properties in the context of how active dwarf galaxies are identified. We use the database constructed in Wasleske & Baldassare (2024) which contains dwarf galaxies that were selected as active galaxies by optical spectroscopy, infrared colors, X-ray brightness, and photometric variability. Multi-wavelength archival data was used to consistently apply all of these methods to every galaxy within this compiled set. The cross application of these methods resulted in a diversity of sub-populations identified as active by some set of these techniques. In this paper, we estimate host galaxy properties from spectral energy distribution models. We connect the active galactic nuclei (AGN) signatures to our estimated host galaxies' properties using statistical dimensionality reduction methods. We find that dwarf AGN selected by infrared colors are the most distinct population, with the highest star formation rates and lowest stellar masses. We also find some other key population differences, such as the broad line AGN having significantly higher AGN luminosities. X-ray and variability selected AGN have higher average star formation rates than those selected with optical narrow line spectroscopic diagrams. Our connections to the host galaxy parameters potentially point to the sub-populations representing different epochs of the evolution of accretion.

Figures (1)

• Figure 1: SED models for NSA 18993(top) and NSA 77755(bottom). NSA 18993 was selected as an AGN via the BPT and [He$\;$] diagrams, as a Seyfert on the [S$\;$] diagram, and from its broad H$\alpha$ and X-ray emissions. In contrast, NSA 77755 was only selected based on optical variability.