Is the Cygnus Superbubble a Hypernova Remnant?

TL;DR

This study uses X-ray observations to analyze the Cygnus Superbubble, revealing its composition, temperature, and potential origin, suggesting it is likely a hypernova remnant powered by stellar winds and possibly a hypernova event.

Contribution

First detection of specific emission lines from the CSB with spectral analysis, indicating its plasma properties and supporting the hypernova origin hypothesis.

Findings

Detected Fe, Ne, Mg emission lines in the CSB.

The plasma temperature is approximately 0.3 keV.

The energy budget suggests a hypernova origin.

Abstract

We present here the observation of the Cygnus Superbubble (CSB) using the Solid-state slit camera (SSC) aboard the Monitor of All-sky X-ray Image. The CSB is a large diffuse structure in the Cygnus region with enhanced soft X-ray emission. By utilizing the CCD spectral resolution of the SSC, we detect Fe, Ne, Mg emission lines from the CSB for the first time. The best fit model implies thin hot plasma of kT ~ 0.3 keV with depleted abundance of 0.26 +/- 0.1 solar. Joint spectrum fitting of the ROSAT PSPC data and MAXI/SSC data enables us to measure precise values of NH and temperature inside the CSB. The results show that all of the regions in the CSB have similar NH and temperature, indicating that the CSB is single unity. The energy budgets calculation suggests that 2-3 Myrs of stellar wind from the Cyg OB2 is enough to power up the CSB, whereas due to its off center position, the origin of the CSB is most likely a Hypernova.