Exploring X-ray Properties of Low Metallicity Dwarf Galaxies

TL;DR

This study investigates the X-ray characteristics of low metallicity dwarf galaxies to identify potential intermediate mass black holes and compare their properties with higher metallicity galaxies, shedding light on early galaxy evolution.

Contribution

It provides the first systematic analysis of X-ray emissions in low metallicity dwarf galaxies, highlighting potential IMBH candidates and differences in multi-wavelength scaling relations.

Findings

Detected 10 sources with luminosity >10^40 erg/s as IMBH candidates.

Found differing X-ray scaling relations between low and high metallicity galaxies.

Observed X-ray luminosity dependence on metallicity.

Abstract

One of the primary outstanding questions in extragalactic astronomy is the formation and early evolution of the supermassive black holes that are seen in nearly every massive galaxy. Low metallicity dwarf galaxies may offer the most representative local analogs to pristine early galaxies, making them a vital tool in probing black hole seed models through the study of the intermediate mass black holes (IMBHs) possibly hosted therein, though these dwarf galaxies, and the IMBHs they may host, are typically not as well-studied in this context as their higher metallicity and higher mass counterparts. In this paper, we explore the X-ray properties of a sample of 37 low metallicity dwarf galaxies using archival XMM observations, and we compare the properties of this population against a representative sample of higher metallicity counterparts. We report the detection of ten sources with 0.3-10 keV luminosity in excess of $10^{40}$~erg~s$^{-1}$ within the low metallicity sample, which we highlight for follow-up as potential intermediate mass black hole candidates. Finally, we discuss the differing multi-wavelength scaling relations (e.g., $L_X - L_{W2}$, $L_X-SFR$) between the two galaxy populations, as well as the sample's $L_X$ as a function of metallicity.