# Blazar Jets Perturbed by Magneto-Gravitational Stresses in Supermassive Binaries

## TL;DR

This paper models how gravitational perturbations in supermassive binary systems can induce magneto-hydrodynamic stresses in blazar jets, leading to recurring high-energy emissions across optical to gamma-ray bands, with implications for observed variability.

## Contribution

It introduces a novel model linking binary-induced jet perturbations to specific, recurring multi-band emission patterns in blazars, especially in PG 1553+113.

## Key findings

- Increased magnetic field strength correlates with optical synchrotron emission peaks.
- Electrons are up-scattering photons to GeV energies via Synchrotron-Self Compton processes.
- Model predicts recurring high peaks and broad troughs in optical to gamma-ray emissions.

## Abstract

We study particle acceleration and radiative processes in Blazar jets under recurring conditions set by gravitational perturbations in supermassive binary systems. We consider the action from a companion orbiting a primary black hole of $\sim 10^8 \, M_{\odot}$, and perturbing its relativistic jet. We discuss how such conditions induce repetitive magneto-hydrodynamic stresses along the jet, and affect its inner electron acceleration and radiative processes. Specifically, we study how macroscopic perturbations related to increased jet "magnetization" end up into higher radiative outputs in the optical, X-ray and gamma-ray bands. We find first an increase in magnetic field strength as gauged in the optical band from the Synchrotron emission of electrons accelerated in kinetic processes stimulated by reconnecting magnetic lines. The energetic electrons then proceed to up-scatter the Synchrotron photons to GeV energies after the canonical Synchrotron-Self Compton radiation process. Our model implies a specific, recurring pattern in the optical to gamma-ray emissions, made of high peaks and wide troughs. Progressing accelerations caused by spreading reconnections will produce an additional Synchrotron keV component. Such outbursts provide a diagnostics for enhanced acceleration of electrons which can up-scatter photons into the TeV range. We discuss how our model applies to the BL Lac object PG 1553+113, arguably the best candidate to now for high amplitude, recurring modulations in its gamma-ray emissions. We also consider other BL Lacs showing correlated keV - TeV radiations such as Mrk 421.