Modeling non-thermal emission from stellar bow shocks

TL;DR

This paper models non-thermal emission from stellar bow shocks created by runaway stars, confirming X-ray emission in some cases and predicting potential high-energy emissions, thus identifying bow shocks as possible nearby high-energy photon sources.

Contribution

It applies and tests theoretical models of non-thermal emission from stellar bow shocks on specific stars, including AE Aurigae and BD+43 3654, and predicts emissions during stellar transition phases.

Findings

X-ray emission from AE Aurigae's bow shock explained by inverse Compton scattering.

Predicted low high-energy flux from BD+43 3654's bow shock.

Potential high-energy emission during supergiant transition phases.

Abstract

Runaway O- and early B-type stars passing throughout the interstellar medium at supersonic velocities and characterized by strong stellar winds may produce bow shocks that can serve as particle acceleration sites. Previous theoretical models predict the production of high energy photons by non-thermal radiative processes, but their efficiency is still debated. We aim to test and explain the possibility of emission from the bow shocks formed by runaway stars traveling through the interstellar medium by using previous theoretical models. We apply our model to AE Aurigae, the first reported star with an X-ray detected bow shock, to BD+43 3654, in which the observations failed in detecting high energy emission, and to the transition phase of a supergiant star in the late stages of its life.From our analysis, we confirm that the X-ray emission from the bow shock produced by AE Aurigae can be explained by inverse Compton processes involving the infrared photons of the heated dust. We also predict low high energy flux emission from the bow shock produced by BD+43 3654, and the possibility of high energy emission from the bow shock formed by a supergiant star during the transition phase from blue to red supergiant.Bow shock formed by different type of runaway stars are revealed as a new possible source of high energy photons in our neighbourhood.