PHYSICS REVEALED BY BROAD-RANGE CO LADDERS AND FINE-STRUCTURE LINES IN M83

Since the launch of the Herschel Space Observatory, our understanding about the photo-dissociation regions (PDR) has taken a step forward. In the bandwidth of the Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board Herschel, ten CO rotational transitions, including $J=4-3$ to $J=13-12$, and three fine structure lines, including [C\textsc{i}]~$609$, [C\textsc{i}]~$370$, and [N\textsc{ii}] $205\,\mathrm{\mu m}$, are covered. I present our findings from the FTS observations at the nuclear region of M83, based on the spatially resolved physical parameters derived from the CO spectral line energy distribution (SLED) map and the comparisons with the dust properties and star-formation tracers. This article discusses(1) the potential of using [N\textsc{ii}] 205 and [C\textsc{i}]~$370\,\mathrm{\mu m}$ as star-formation tracers;(2) the excitation mechanisms of warm CO in the nuclear region of M83.