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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 × 109M⊙,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(L2−10 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 ofMBH∼ 105−6M⊙and Eddington ratios on the order of ∼10−3.
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A Luminous X-Ray Active Galactic Nucleus in the Dwarf–Dwarf Galaxy Merger RGG 66
Abstract We present the discovery of a luminous X-ray active galactic nucleus (AGN) in the dwarf galaxy merger RGG 66. The black hole is predicted to have a mass ofMBH∼ 105.4M⊙and to be radiating close to its Eddington limit (Lbol/LEdd∼ 0.75). The AGN in RGG 66 is notable both for its presence in a late-stage dwarf–dwarf merger and for its luminosity ofL2–10 keV= 1042.2erg s−1, which is among the most powerful AGNs known in nearby dwarf galaxies. The X-ray spectrum has a best-fit photon index of Γ = 2.4 and an intrinsic absorption ofNH∼ 1021cm−2. These results come from a follow-up Chandra X-ray Observatory study of four irregular/disturbed dwarf galaxies with evidence for hosting AGNs based on optical spectroscopy. The remaining three dwarf galaxies do not have detectable X-ray sources with upper limits ofL2–10 keV≲ 1040erg s−1. Taken at face value, our results on RGG 66 suggest that mergers may trigger the most luminous of AGNs in the dwarf galaxy regime, just as they are suspected to do in more massive galaxy mergers.
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- Award ID(s):
- 2235277
- PAR ID:
- 10546709
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 974
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 51
- Size(s):
- Article No. 51
- Sponsoring Org:
- National Science Foundation
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