Other Types of Source Extraction and Identification

Extraction of astronomical electromagnetic wave information from radio observations is crucial to our understanding of the Universe. However, it also has multiple levels of complexity and is still challenging in the big-data era. In this chapter, we reveal part of this complexity by describing three types of astronomical information—spectral line emission, polarisation, and time domain information. They are widely used techniques to study the fundamental physics of interstellar medium, galaxies and high-energy phenomenon in the Universe. This chapter shows how to exploit these extra ‘dimensions’ of radio data other than the radio continuum. These techniques will be ever more powerful in the coming years due to the ever-larger radio observing facilities like the Square Kilometer Array. In this chapter we discuss the commonly used extraction methods of other information like spectral lines (only if within the bandwidth), polarisation (if emission is polarised), and time domain properties (if the source has time variation, e.g. in case of pulsars or fast radio bursts).