Nonthermal X-ray Emission from the N11 Superbubble in the Large Magellanic Cloud

TL;DR

This study analyzes X-ray emissions from the N11 superbubble in the Large Magellanic Cloud, revealing a nonthermal component and energy discrepancies with stellar input.

Contribution

It provides the first detailed spectral analysis of N11's superbubble using Suzaku data, identifying nonthermal X-ray emission and energy budget inconsistencies.

Findings

Detected nonthermal X-ray emission with photon index Γ=1.72

Found thermal and kinetic energy are half of expected stellar input

Constrained plasma properties using combined Suzaku and XMM-Newton data

Abstract

We present the results of X-ray spectral analysis of the superbubble around the OB association LH9 in the H II complex N11 in the Large Magellanic Cloud. Using observations from Suzaku, we have modeled the X-ray emission over the energy range 0.2-7.5 keV. We constrained the thermal spectrum below 2 keV using a thermal plasma model found in a previous XMM-Newton study of the N11 region. We find that the hard X-ray emission (> 2 keV) requires a nonthermal power-law component. The photon index of this component was found to be $\Gamma=1.72\pm 0.15$. We performed an energy budget analysis for N11 using the known stellar content of LH9. We found that the observed thermal and kinetic energy in the superbubble is only half of the expected mechanical energy injected by stars.