On spin dependence of the fundamental plane of black hole activity

Caner Ünal, Abraham Loeb

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The Fundamental Plane (FP) of black hole (BH) activity in galactic nuclei relates X-ray and radio luminosities to BH mass and accretion rate. However, there is a large scatter exhibited by the data, which motivated us for a new variable. We add BH spin as a new variable and estimate the spin dependence of the jet power and disc luminosity in terms of radio and X-ray luminosities. We assume the Blandford–Znajek process as the main source of the outflow, and find that the jet power depends on BH spin stronger than quadratically at moderate and large spin values. We perform a statistical analysis for 10 active galactic nuclei (AGNs) which have sub-Eddington accretion rates and whose spin values are measured independently via the reflection or continuum-fitting methods, and find that the spin-dependent relation describes the data significantly better. This analysis, if supported with more data, could imply not only the spin dependence of the FP relation, but also the Blandford–Znajek process in AGN jets.

Original languageEnglish
Pages (from-to)278-284
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 1 Jun 2020
Externally publishedYes


  • Accretion
  • Accretion discs
  • Black hole physics
  • Galaxies: Jets
  • Quasars: Individual: Supermassive black holes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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