A Large-field J=1-0 Survey of CO and Its Isotopologues toward the Cassiopeia A Supernova Remnant

We have conducted a large-field simultaneous survey of (CO)-C-12, (CO)-C-13, and (CO)-O-18 J = 1 - 0 emission toward the Cassiopeia A (Cas A) supernova remnant (SNR), which covers a sky area of 3 degrees.5 x 3 degrees.1. The Cas giant molecular cloud (GMC) mainly consists of three individual clouds with masses on the order of 10(4)-10(5) M-circle dot. The total mass derived from the (CO)-C-13 emission of the GMC is 2.1 x 10(5) M-circle dot and is 9.5 x 10(5) M-circle dot from the (CO)-C-12 emission. Two regions with broadened (6-7 km s(-1)) or asymmetric (CO)-C-12 line profiles are found in the vicinity (within a 10' x 10' region) of the Cas A SNR, indicating possible interactions between the SNR and the GMC. Using the GAUSSCLUMPS algorithm, 547 (CO)-C-13 clumps are identified in the GMC, 54% of which are supercritical (i.e., alpha(vir) < 2). The mass spectrum of the molecular clumps follows a power-law distribution with an exponent of -2.20. The pixel-by-pixel column density of the GMC can be fitted with a log-normal probability distribution function (N-PDF). The median column density of molecular hydrogen in the GMC is 1.6 x 10 (21) cm(-2) and half the mass of the GMC is contained in regions with H-2 column density lower than 3 x 10(21) cm(-2), which is well below the threshold of star formation. The distribution of the YSO candidates in the region shows no agglomeration.