Chemical models and experiments indicate that interstellar dust grains and
their ice mantles play an important role in the production of complex organic
molecules (COMs). To date, the most complex solid-phase molecule detected with
certainty in the ISM is methanol, but the James Webb Space Telescope (JWST) may
be able to identify still larger organic species. In this study, we use a
coupled chemo-dynamical model to predict new candidate species for JWST
detection toward the young star-forming core Cha-MMS1, combining the gas-grain
chemical kinetic code MAGICKAL with a 1-D radiative hydrodynamics simulation
using Athena++. With this model, the relative abundances of the main ice
constituents with respect to water toward the core center match well with
typical observational values, providing a firm basis to explore the ice
chemistry. Six oxygen-bearing COMs (ethanol, dimethyl ether, acetaldehyde,
methyl formate, methoxy methanol, and acetic acid), as well as formic acid,
show abundances as high as, or exceeding, 0.01% with respect to water ice.
Based on the modeled ice composition, the infrared spectrum is synthesized to
diagnose the detectability of the new ice species. The contribution of COMs to
IR absorption bands is minor compared to the main ice constituents, and the
identification of COM ice toward the core center of Cha-MMS1 with the JWST
NIRCAM/Wide Field Slitless Spectroscopy (2.4-5.0 micron) may be unlikely.
However, MIRI observations (5-28 micron) toward COM-rich environments where
solid-phase COM abundances exceed 1% with respect to the water ice column
density might reveal the distinctive ice features of COMs.
Comment: Accepted to ApJ (28 Pages, 11 figures)
Subjects: Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies