On the Physical Origins of the Millimeter Fundamental Plane in Active Galactic Nuclei

TL;DR

This study shows that a hot, magnetized accretion flow around black holes can naturally produce the observed correlation between millimeter, X-ray luminosity, and black hole mass in active galactic nuclei, aligning simulations with observations.

Contribution

The paper demonstrates through simulations that magnetic, relativistic accretion flows can explain the millimeter and X-ray emission correlation in low-luminosity AGN without tuning parameters.

Findings

Inverse Compton scattering dominates X-ray production.

Models with similar Eddington ratios reproduce observations.

Weak spin dependence observed in the correlation.

Abstract

Observations of active galactic nuclei have revealed a correlation between millimeter luminosity, X-ray luminosity, and mass, suggesting the emission in each of these bands is powered by a common source. Starting with a set of five general relativistic magnetohydrodynamic simulations with dynamically important magnetic fields, we perform ray-tracing calculations to produce spectra including synchrotron emission, bremsstrahlung emission, and Compton scattering. Our models with similar Eddington ratios to the objects for which the relationship was inferred naturally reproduce observations without tuning. Our lower Eddington ratio models depart from this relationship, likely attributable to an observational bias against extremely low accretion rates. We find that inverse Compton scattering dominates the production of X-rays over bremsstrahlung radiation in almost all models, and in all models consistent with the observed correlation. We find only a modest spin dependence in this relationship. This study demonstrates that a compact, hot accretion flow with dynamically important magnetic fields can naturally explain observed millimeter and X-ray properties in low-luminosity active galactic nuclei. Future work should explore the impacts of non-thermal electron populations, weaker magnetic fields, and radiative cooling.