Criss-cross Nebula: A Case Study of Shock Regions with Resolved Microstructures at Scales of 1000 au

Using integral field spectroscopy (IFS) from MaNGA, we study the resolved microstructures in a shocked region in the Criss-cross Nebula (CCN), with an unprecedentedly high resolution of less than or similar to 1000 au. We measure surface brightness maps for 34 emission lines, which can be broadly divided into three categories: (1) the [O iii] lambda 5007-like group including seven high-ionization lines and two [O ii] auroral lines that uniformly present a remarkable lane structure, (2) the H alpha lambda 6563-like group, including 23 low-ionization or recombination lines that present a clump-like structure, and (3) [O ii] lambda 3726 and [O ii] lambda 3729 showing high densities at both the [O iii] lambda 5007 lane and the H alpha clump. We use these measurements to constrain resolved shock models implemented in MAPPINGS V. We find our data can be reasonably well fitted by a model that includes a plane-parallel shock with a velocity of 133 +/- 5 km s -1, plus an isotropic two-dimensional Gaussian component, which is likely another clump of gas ionized by photons from the shocked region, and a constant background. We compare the electron density and temperature profiles as predicted by our model with those calculated using observed emission-line ratios. We find different line ratios to provide inconsistent temperature maps, and the discrepancies can be attributed to observational effects caused by limited spatial resolution and projection of the shock geometry, as well as contamination of the additional Gaussian component. Implications on shock properties and perspectives on future IFS-based studies of the CCN are discussed.