X-ray emission from massive stars with magnetic fields

TL;DR

This paper explores how magnetic fields influence X-ray emissions in massive stars, revealing diverse behaviors and proposing a hybrid model involving surface magnetism and wind shocks to explain observed correlations.

Contribution

It introduces a hybrid scenario combining magnetic surface activity and wind shocks to explain X-ray emissions in massive stars, addressing longstanding mysteries.

Findings

Magnetic massive stars show diverse X-ray properties.

Strong, hard, variable X-ray emission may indicate magnetism.

A hybrid model explains X-ray emission via surface magnetism and wind shocks.

Abstract

We investigate the connections between the magnetic fields and the X-ray emission from massive stars. Our study shows that the X-ray properties of known strongly magnetic stars are diverse: while some comply to the predictions of the magnetically confined wind model, others do not. We conclude that strong, hard, and variable X-ray emission may be a sufficient attribute of magnetic massive stars, but it is not a necessary one. We address the general properties of X-ray emission from "normal" massive stars, especially the long standing mystery about the correlations between the parameters of X-ray emission and fundamental stellar properties. The recent development in stellar structure modeling shows that small scale surface magnetic fields may be common. We suggest a "hybrid" scenario which could explain the X-ray emission from massive stars by a combination of magnetic mechanisms on the surface and shocks in the stellar wind. The magnetic mechanisms and the wind shocks are triggered by convective motions in sub-photospheric layers. This scenario opens the door for a natural explanation of the well established correlation between bolometric and X-ray luminosities.