Methanol Mapping in Cold Cores: Testing Model Predictions*

Chemical models predict that in cold cores gas-phase methanol is expected to be abundant at the outer edge of CO depletion zone, where actively adsorbed. adsorption correlates with volume density cores, and, nearby molecular clouds, catastrophic freeze-out happens densities above 10$^4$ cm$^{-3}$. The production rate maximized there and its does not overcome rate, while molecules are shielded from UV destruction by gas dust. Thus, abundance should generally correlate visual extinction depends both on column density. In this work, we test most basic model prediction maximum associated a local $A_V\simeq$4 mag dense constrain parameters observational data. With IRAM 30 m antenna, mapped CH$_3$OH (2-1) (3-2) transitions toward seven L1495 filament Taurus measure abundance. We use Herschel/SPIRE maps estimate extinction, C$^{18}$O(2-1) Tafalla & Hacar (2015) depletion. explored observed modeled correlations between abundances, depletion, varying key parameters. modeling results show hydrogen surface diffusion via tunneling crucial reproduce needed reactive desorption efficiency matches one deduced laboratory experiments.