A Deeper Look into eFEDS AGN Candidates in Dwarf Galaxies with Chandra

Abstract

The ability to accurately discern active massive black holes (BHs) in nearby dwarf galaxies is paramount to understanding the origins and processes of “seed” BHs in the early Universe. We present Chandra X-ray Observatory observations of a sample of three local dwarf galaxies ( M _* ≤ 3 × 10 ^9 M _⊙ , z ≤ 0.15) previously identified as candidates for hosting active galactic nuclei (AGN). The galaxies were selected from the NASA-Sloan Atlas with spatially coincident X-ray detections in the eROSITA Final Equatorial Depth Survey. Our new Chandra data reveal three X-ray point sources in two of the target galaxies with luminosities between log( L _2−10 keV [erg s ^−1 ]) = 39.1 and 40.4. Our results support the presence of an AGN in these two galaxies and an ultraluminous X-ray source (ULX) in one of them. For the AGNs, we estimate BH masses of M _BH ∼ 10 ^5−6 M _⊙ and Eddington ratios on the order of ∼10 ^−3 .

Keywords

• Black holes
• Dwarf galaxies
• X-ray active galactic nuclei
• Active galactic nuclei