Accretion Disk MHD Winds and Blazar Classification

TL;DR

This paper models blazar emissions by linking gamma-ray spectral features to accretion disk MHD winds, explaining observed classification trends through variations in black hole accretion rates.

Contribution

It introduces a model connecting blazar spectral properties to MHD wind-driven external photon fields, reproducing observational trends with a single parameter.

Findings

Reproduces blazar spectral trends by varying accretion rate.

Links gamma-ray spectral index to accretion disk winds.

Explains blazar classification through MHD wind interactions.

Abstract

The Fermi Gamma-Ray Space Telescope observations of blazars show a strong correlation between the spectral index of their gamma-ray spectra and their synchrotron peak frequency $\nu_{\rm{pk}}^{\rm{syn}}$; additionally, the rate of Compton Dominance of these sources also seems to be a function of $\nu_{\rm{pk}}^{\rm{syn}}$. In this work, we adopt the assumption that the nonthermal emission of blazars is primarily due to radiation by a population of Fermi-accelerated electrons in a relativistic outflow (jet) along the symmetry axis of the blazar's accretion disk. Furthermore, we assume that the Compton component is related to an external photon field of photons, which are scattered from particles of the magnetohydrodynamic (MHD) wind emanating from the accretion disk. Our results reproduce well the aforementioned basic observational trends of blazar classification by varying just one parameter, namely the mass accretion rate onto the central black hole.