# Inter-Plasmoid Compton Scattering and the Compton Dominance of BL Lacs

## TL;DR

This paper proposes that inter-plasmoid Compton scattering within magnetic reconnection layers can explain the high Compton ratios observed in BL Lac objects, aligning with energy equipartition models.

## Contribution

It introduces the concept of radiative interactions among plasmoids, specifically inter-plasmoid Compton scattering, as a solution to previous limitations in blazar emission models.

## Key findings

- Inter-plasmoid Compton scattering increases observed Compton ratios.
- Photons from slow, large plasmoids are up-scattered by fast, small plasmoids.
- This process maintains energy equipartition while explaining observations.

## Abstract

Blazar emission models based on magnetic reconnection succeed in reproducing many observed spectral and temporal features, including the short-duration luminous flaring events. Plasmoids, a self-consistent by-product of the tearing instability in the reconnection layer, can be the main source of blazar emission. Kinetic simulations of relativistic reconnection have demonstrated that plasmoids are characterized by rough energy equipartition between their radiating particles and magnetic fields. This is the main reason behind the apparent shortcoming of plasmoid-dominated emission models to explain the observed Compton ratios of BL Lac objects. Here, we demonstrate that the radiative interactions among plasmoids, which have been neglected so far, can assist in alleviating this contradiction. We show that photons emitted by large, slow-moving plasmoids can be a potentially important source of soft photons to be then up-scattered, via inverse Compton, by small fast-moving, neighboring plasmoids. This inter-plasmoid Compton scattering process can naturally occur throughout the reconnection layer, imprinting itself as an increase in the observed Compton ratios from those short and luminous plasmoid-powered flares within BL Lac sources, while maintaining energy equipartition between radiating particles and magnetic fields.