Suzaku Discovery of Twin Thermal Plasma from the Tornado Nebula

TL;DR

This paper reports the discovery of twin thermal X-ray plasmas at both ends of the Tornado nebula, indicating a bipolar or outflow structure, based on Suzaku observations of diffuse emission lines and spectral analysis.

Contribution

It presents the first detection of twin thermal plasma sources associated with the Tornado nebula, revealing its bipolar/outflow nature.

Findings

Twin diffuse X-ray sources with similar temperatures (0.6-0.7 keV)

X-ray sources are likely associated with the Tornado nebula

Supports the bipolar/outflow model of the nebula

Abstract

The Tornado nebula (G357.7-0.1) is a mysterious radio source with bright "head" and faint "tail" located in the direction of the Galactic center (GC) region. We here report the discovery of two diffuse X-ray sources at the head and tail of the Tornado with the Suzaku satellite. We found emission lines from highly ionized atoms in the two sources. The spectra are reproduced by an optically thin thermal plasma with a common temperature of 0.6-0.7 keV. The interstellar absorption (NH) of these sources are the same and are slightly larger than that of the GC distance. Since the estimated distance using the NH value is consistent with the radio observation of the Tornado, these X-ray sources are likely associated with the Tornado nebula. The twin-plasma morphology at the both ends of the Tornado suggests that the system is a bipolar/outflow source.