In-situ acceleration of radio-emitting particles in the lobes of radio galaxies: Evolving observational perspective and recent clues

TL;DR

This paper reviews the history and recent observational evidence for in-situ acceleration of relativistic particles in radio galaxy lobes, highlighting new clues from recent radio observations of a tailed radio source in galaxy cluster Abell 1033.

Contribution

It provides a comprehensive overview of the evolution of understanding in radio galaxy particle acceleration and introduces new observational evidence supporting in-situ acceleration mechanisms.

Findings

New observational clue from Abell 1033 radio data

Historical milestones in plasma physics and radio galaxy studies

Enhanced understanding of particle acceleration in radio lobes

Abstract

The issue of radiation mechanisms had triggered in 1950-60s the first applications of plasma physics to understand the nature of radio galaxies. This interplay has steadily intensified during the past five decades, due to the premise of in-situ acceleration of relativistic electrons occurring in the lobes of radio galaxies. This article briefly traces the chain of these remarkable developments, largely from an observational perspective. We recount several observational and theoretical milestones established along the way and the lessons drawn from them. We also present a new observational clue about in-situ acceleration of the relativistic particles radiating in the lobes of radio galaxies, gleaned by us from the very recently published sensitive radio observations of a tailed radio source in the galaxy cluster Abell 1033.