# Radio synchrotron emission: electron energy spectrum, supernovae, microquasars, active nuclei, cluster relics and halos; X-ray halos

## TL;DR

This paper reviews high-energy transient events and their radio synchrotron signatures across various astrophysical sources, proposing models for electron acceleration, jet formation, and plasma composition, while highlighting unresolved questions in active nuclei and galaxy clusters.

## Contribution

It offers new insights into the origin of radio emission phases, electron energy spectra, and plasma composition in diverse high-energy astrophysical phenomena.

## Key findings

- Ejected matter in explosive events is energized to escape velocity.
- Prompt supernova radio emission is from positron-electron plasma.
- Jets in active nuclei are launched from black hole polar regions.

## Abstract

In this paper, transient high energy events and their hosts are discussed with focus on signatures of radio synchrotron emission. Outstanding questions range from the origin of the two phases of radio emission in supernovae to the formation of conical jets launched at relativistic velocities in active nuclei to the formation of radio hotspots in FR II sources to the formation of radio relics and halos in clusters of galaxies to the origin of the relativistic electron population and its energy spectrum which is responsible for the synchrotron emission to the composition of the radio synchrotron-emitting plasma in these sources. Observations have helped build an empirical model of active nuclei but the origin of the narrow line regions, broad line regions, dust, accretion disk in active nuclei and their connection to radio jets and lobes remains largely unknown. This paper attempts to understand and resolve these. A few results are: 1 The matter ejected in a transient explosive events have to be energised, before ejection, to escape velocity. An important source of transient explosive energy in the universe is thermonuclear. The energy spectrum of the particles energised in such events will follow a normal/gaussian distribution ; 2 The prompt radio synchrotron emission from a supernova is from a positron-electron plasma whereas the delayed radio synchrotron from supernova remnants is due to the relativistic proton-electron plasma mixed with the thermal plasma ; 3 Jets and narrow line gas are launched from the polar regions of the pseudosurface of the rotating black hole in active nuclei by the energy released in a thermonuclear outburst in the accreted matter. Synchrotron jets are composed of positron-electron plasma.