Abstract
Methanol ($CH_3OH$) is a key species in the formation of complex organic molecules. We report the first detection of solid $CH_3OH$ in a line of sight toward the Galactic center (GC) region, based on L-band spectra taken with the Subaru telescope, aided by L'-band imaging data and moderate-resolution spectra from NASA/IRTF. It is found toward a background star, ~8000 AU in projected distance from a newly discovered massive young stellar object (YSO). This YSO also exhibits a strong $CO_2$ ice absorption band at ${\sim}15{\mu}m$ in Spitzer/IRS data, which has a prominent long-wavelength wing. It confirms that a high $CH_3OH$ abundance is responsible for the broad $15{\mu}m$ $CO_2$ ice absorption towards massive YSOs in the GC. Clearly, $CH_3OH$ formation in ices is efficient in the GC region, as it is in star-forming regions in the Galactic disk. We discuss implications of our result on the astrochemical processes in the hostile GC molecular clouds.