X-ray and radio observations of central black holes in nearby low-mass early-type galaxies: Preliminary evidence for low Eddington fractions

Abstract

We present new radio and X-ray observations of two nearby ($<4$ Mpc) low-mass early-type galaxies with dynamically-confirmed central black holes: NGC 5102 and NGC 205. NGC 5102 shows a weak nuclear X-ray source and has no core radio emission. However, for the first time we demonstrate that it shows luminous extended radio continuum emission in low-resolution, low-frequency ($<3$ GHz) data, consistent with jet lobes on scales $\gtrsim 100$ pc formed from past accretion and jet activity. By contrast, in new, extremely deep, strictly-simultaneous Very Large Array and Chandra observations, no radio or X-ray emission is detected from the black hole in NGC 205. We consider these measurements and upper limits in the context of the few other low-mass early-type galaxies with dynamically-confirmed black holes, and show that the mean ratio of bolometric to Eddington luminosity in this sample is only $\text{log}(L_{\mathrm{bol}}/L_{\mathrm{Edd}})=-6.57\pm 0.50$. These Eddington ratios are lower than typical in a comparison sample of more massive early-type galaxies, though this conclusion is quite tentative due to our small sample of low-mass galaxies and potential biases in the comparison sample. This preliminary result is in mild tension with previous work using less sensitive observations of more distant galaxies, which predict higher X-ray luminosities than we observe for low-mass galaxies. If it is confirmed that central black holes in low-mass galaxies typically have low Eddington ratios, this presents a challenge to measuring the occupation fraction of central black holes with standard optical emission line, X-ray, or radio surveys.

13 pages, 4 figures, 3 tables. Accepted for publication in ApJ

References in corpus (21)

• The Gaia mission
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Intermediate-Mass Black Holes
• The Assembly of the First Massive Black Holes
• Radiatively Inefficient Accretion in Nearby Galaxies
• The Rapid ASKAP Continuum Survey I: Design and First Results
• A New Sample of (Wandering) Massive Black Holes in Dwarf Galaxies from High Resolution Radio Observations
• Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei And the First Black Hole Determination for NGC 205
• Two Planes of Satellites in the Centaurus A Group
• X-ray constraints on the local supermassive black hole occupation fraction
• The Fundamental Plane of Black Hole Accretion and its Use as a Black Hole-Mass Estimator
• Improved Dynamical Constraints on the Mass of the central Black Hole in NGC 404
• Dominant dark matter and a counter rotating disc: MUSE view of the low luminosity S0 galaxy NGC 5102
• Revealing the intermediate-mass black hole at the heart of the dwarf galaxy NGC 404 with sub-parsec resolution ALMA observations
• Exploring the local black hole mass function below $10^6$ solar masses
• A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN hosted by NGC404
• The AGN Fraction in Dwarf Galaxies from eROSITA: First Results and Future Prospects
• The ultraluminous X-ray source bubble in NGC 5585
• Surprisingly Strong K-band Emission Found in Low Luminosity Active Galactic Nuclei
• Spatially Resolving the Star Formation Histories of Three Nearby Nuclear Star Clusters
• Resolving the Nuclear Radio Emission from M32 with Very Large Array

Cited by in corpus (3)

• Intermediate-mass black holes: finding of episodic, large-scale and powerful jet activity in a dwarf galaxy
• Demographics of Tidal Disruption Events with L-Galaxies: I. Volumetric TDE rates and the abundance of Nuclear Star Clusters
• Cosmic quenching and scaling laws for the evolution of supermassive black holes and host galaxies