Large-scale 13CO J=5→4 and [C I] mapping Of Orion A

We present maps of the (CO)-C-13 J = 5 --> 4 (551 GHz) and [C I] P-3(1) --> P-3(0) (492 GHz) emission in the Orion A molecular cloud, covering a 0 degrees.5 x 2 degrees area. A large velocity gradient (LVG) analysis of (CO)-C-13 J = 5 --> 4 and J = 1 --> 0 suggests that the gas temperatures in the northern part of OMC-1. (north of Delta delta = -20') are similar to 45 K and are, on average, at least 20 K higher than those to the south. The average (CO)-C-13 column density is log (N/cm(-2)) = 16.4 +/- 0.3 and is fairly constant throughout the cloud, even in the low-temperature region south of BN/KL. LVG modeling of the [C I] emission shows a typical C-0 column density of 2 x 10(17) cm(-2), which yields a C/CO abundance ratio in the cloud of similar to 0.1 (rising to levels in excess of 0.5 at the cloud edges). Comparison of the Delta-variance (which measures spatial structure in a manner similar to a power spectrum) of the Submillimeter Wave Astronomy Satellite [C I], Five College Radio Astronomy Observatory (CO)-C-13 J = 1 --> 0, and CS J = 1 --> 0 velocity-integrated maps suggests that the [C I] and (CO)-C-13 emission arise from the same gas. In contrast, the CS emission likely originates in gas that is considerably more clumpy.