Separation And Study Of Thermal And Non-thermal Emission In The Cygnus X Region

Total power observation of the Galaxy at radio bands is a powerful tool to study theinterstellar medium (ISM). The emission observed at decimeter and centimeter wavelengths inthe radio domain is overwhelmingly contributed by two mechanisms: the thermal bremsstrahlungradiation (free-free emission) and the non-thermal synchrotron radiation. The Cygnus X region isone of the most complex areas in the Galactic plane. A number of thermal and non-thermal radiostructures are overlapped with each other and highly confused by the diffuse Galactic emission.Lots of the radio sources have not been identified in this region. Separation of the thermal andnon-thermal emission is a primary tool to investigate the properties of this region, it is veryuseful to the study of the structure of the Galaxy.Our main goal is to develop a method which can properly separate the thermal andnon-thermal components of radio emission in the Cygnus X region and study their properties.Multi-frequency radio continuum data from large-scale surveys are used for the componentseparation in this region. The thermal and non-thermal components are dissociated by means of aspectral index analysis through fitting the global Galactic emission pixel by pixel by the thermalfree-free emission component with a fixed spectral index of β=-2.1. The new method solve theobvious inaccuracies and limitations of the previous templates, and enhance the identification ofsmall-scale structures. We can also get the non-thermal radiation spectral index by each pixel.The large-scale data can be corrected in every region by our results.With the new method, we separate the thermal and non-thermal components of the Cygnus Xregion at an angular resolution of9.5′. The thermal emission component comprises39%of thetotal continuum emission in a part of the Cygnus X region (66°≤l≤90°，|b|≤4°) at λ6cm.Diffuse emission, rather than discrete H II regions, is the major contribution to the thermalbudget. We successfully separate out the large-extent known supernova remnants (SNRs) and theH II regions embedded in the complex. Unfortunately, no new large SNRs are found.