The CARMA-NRO Orion Survey: The filamentary structure as seen in
  C$^{18}$O emission
  We present an initial overview of the filamentary structure in the Orion A
molecular cloud utilizing a high angular and velocity resolution C$^{18}$O(1-0)
emission map that was recently produced as part of the CARMA-NRO Orion Survey.
The main goal of this study is to build a credible method to study varying
widths of filaments which has previously been linked to star formation in
molecular clouds. Due to the diverse star forming activities taking place
throughout its $\sim$20 pc length, together with its proximity of 388 pc, the
Orion A molecular cloud provides an excellent laboratory for such an experiment
to be carried out with high resolution and high sensitivity. Using the
widely-known structure identification algorithm, DisPerSE, on a 3-dimensional
(PPV) C$^{18}$O cube, we identified 625 relatively short (the longest being
1.74 pc) filaments over the entire cloud. We study the distribution of filament
widths using FilChaP, a python package that we have developed and made publicly
available. We find that the filaments identified in a 2 square degree PPV cube
do not overlap spatially, except for the complex OMC-4 region that shows
distinct velocity components along the line of sight. The filament widths vary
between 0.02 and 0.3 pc depending on the amount of substructure that a filament
possesses. The more substructure a filament has, the larger is its width. We
also find that despite this variation, the filament width shows no
anticorrelation with the central column density which is in agreement with
previous Herschel observations.
