Symmetry properties and widths of the filamentary structures in the Orion A giant molecular cloud

We identify 225 filaments from an H-2 column density map constructed using simultaneous (CO)-C-12, (CO)-C-13 and (CO)-O-18 (J = 1-0) observations carried out as a part of the Milky Way Imaging Scroll Painting (MWISP) project.We select 46 long filaments with lengths above 1.2 pc to analyze the filament column density profiles. We divide the selected filaments into 397 segments and calculate the column density profiles for each segment. The symmetries of the profiles are investigated. The proportion of intrinsically asymmetrical segments is 65.3%, and that of intrinsically symmetrical ones is 21.4%. The typical full width at half maximum (FWHM) of the intrinsically symmetrical filament segments is similar to 0.67 pc with the Plummer-like fitting, and similar to 0.50 pc with the Gaussian fitting, respectively. The median FWHMs derived from the second-moment method for intrinsically symmetrical and asymmetrical profiles are similar to 0.44 and 0.46 pc, respectively. Close association exists between the filamentary structures and the YSOs in the region.