A Fundamental Line of Black Hole Activity

Ruth A. Daly, Douglas A. Stout, Jeremy N. Mysliwiec

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14 Scopus citations


Black hole systems with outflows are characterized by intrinsic physical quantities such as the outflow beam power, L j, the bolometric accretion disk luminosity, L bol, and black hole mass or Eddington luminosity, L Edd. When these systems produce compact radio emission and X-ray emission, they can be placed on the fundamental plane (FP), an empirical relationship between compact radio luminosity, X-ray luminosity, and black hole mass. We consider a fundamental line (FL) of black hole activity written in terms of dimensionless intrinsic physical quantities: log(L j/L Edd) = A log(L bol/L Edd) + B or equivalently log(L j/L bol) = (A - 1) log(L bol/L Edd) + B, and show that the FP may be written in the form of the FL. The FL has a smaller dispersion than the FP, suggesting the FP derives from the FL. Disk-dominated and jet-dominated systems have consistent best-fit FL parameters that suggest they are governed by the same physics. There are sharp cutoffs at L bol/L Edd ≃ 1 and L j/L Edd ≃ 0.2, and no indication of a strong break as . Consistent values of A are obtained for numerous samples, including FRII sources, LINERS, AGNs with compact radio emission, and Galactic black holes, which indicate a weighted mean value of A ≃ 0.45 ± 0.01. The results suggest that a common physical mechanism related to the dimensionless bolometric luminosity of the disk controls the jet power relative to the disk power. The beam power L j can be obtained by combining FP best-fit parameters and compact radio luminosity for sources that fall on the FP.

Original languageEnglish (US)
Article number117
JournalAstrophysical Journal
Issue number2
StatePublished - Aug 20 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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