Intermediate-mass black holes and the Fundamental Plane of black hole accretion
Reines, Amy E
Greene, Jenny E
Cackett, Edward M
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We present new 5 GHz Very Large Array observations of a sample of eight active intermediate-mass black holes with masses 104.9 M⊙ < M < 106.1 M⊙ found in galaxies with stellar masses M* < 3 × 109 M⊙. We detected five of the eight sources at high significance. Of the detections, four were consistent with a point source, and one (SDSS J095418.15+471725.1, with black hole mass M < 105 M⊙) clearly shows extended emission that has a jet morphology. Combining our new radio data with the black hole masses and literature X-ray measurements, we put the sources on the Fundamental Plane of black hole accretion. We find that the extent to which the sources agree with the Fundamental Plane depends on their star-forming/composite/active galactic nucleus (AGN) classification based on optical narrow emission-line ratios. The single star-forming source is inconsistent with the Fundamental Plane. The three composite sources are consistent, and three of the four AGN sources are inconsistent with the Fundamental Plane. We argue that this inconsistency is genuine and not a result of misattributing star formation to black hole activity. Instead, we identify the sources in our sample that have AGN-like optical emission-line ratios as not following the Fundamental Plane and thus caution the use of the Fundamental Plane to estimate masses without additional constraints, such as radio spectral index, radiative efficiency, or the Eddington fraction.
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society 2022 Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Kayhan Gültekin, Kristina Nyland, Nichole Gray, Greg Fehmer, Tianchi Huang, Matthew Sparkman, Amy E Reines, Jenny E Greene, Edward M Cackett, Vivienne Baldassare, Intermediate-mass black holes and the Fundamental Plane of black hole accretion, Monthly Notices of the Royal Astronomical Society, Volume 516, Issue 4, November 2022, Pages 6123–6131, https://doi.org/10.1093/mnras/stac2608