Cause of the reduced CO ice column density in the L1527 disk lane

Determine whether the lower CO ice column densities measured in the disk lane of the low-mass protostar L1527 are caused by thermal CO ice desorption rather than by the weak continuum and resulting loss of the absorption feature into the noise.

Background

The CO ice maps of L1527 show lower apparent column densities in the central disk lane than along the outflow-cavity lines of sight. The authors explain that the weak continuum in the dark disk lane causes the strong CO absorption band to fall into the noise floor, which can produce artificially low integrated optical depths and column densities.

A warm-disk interpretation remains possible because gas-phase studies indicate temperatures sufficient to prevent CO freeze-out. However, the observations do not establish whether the apparent CO deficit is physical or an observational artifact, and the authors explicitly state that they cannot determine the cause conclusively.