X-Ray emission from SN 2004dj: A Tale of Two Shocks

TL;DR

This study analyzes X-ray emissions from SN 2004dj to understand the roles of shocks, particle acceleration, and magnetic fields, revealing that inverse Compton scattering and thermal emission both contribute to observed X-ray signals.

Contribution

It provides a detailed quantitative analysis of the origins of X-ray emission in a Type IIP supernova, highlighting the relative efficiencies of particle acceleration and magnetic field amplification.

Findings

Electrons are more efficiently accelerated than magnetic fields.

X-ray emission results from inverse Compton scattering and thermal emission.

Pre-explosion mass loss rate and shock velocities are estimated.

Abstract

Type IIP (Plateau) Supernovae are the most commonly observed variety of core collapse events. They have been detected in a wide range of wavelengths from radio, through optical to X-rays. The standard picture of a type IIP supernova has the blastwave interacting with the progenitor's circumstellar matter to produce a hot region bounded by a forward and a reverse shock. This region is thought to be responsible for most of the X-ray and radio emission from these objects. Yet the origin of X-rays from these supernovae is not well understood quantitatively. The relative contributions of particle acceleration and magnetic field amplification in generating the X-ray and radio emission need to be determined. In this work we analyze archival Chandra observations of SN 2004dj, the nearest supernova since SN 1987A, along with published radio and optical information. We determine the pre-explosion mass loss rate, blastwave velocity, electron acceleration and magnetic field amplification efficiencies. We find that a greater fraction of the thermal energy goes into accelerating electrons than into amplifying magnetic fields. We conclude that the X-ray emission arises out of a combination of inverse Compton scattering by non-thermal electrons accelerated in the forward shock and thermal emission from supernova ejecta heated by the reverse shock.