AKARI Near-Infrared Spectroscopic Observations of Interstellar Ices in
  Edge-on Starburst Galaxy NGC253
  We present the spatially-resolved near-infrared (2.5-5.0 um) spectra of the
edge-on starburst galaxy NGC253 obtained with the Infrared Camera onboard
AKARI. Near the center of the galaxy, we clearly detect the absorption features
of interstellar ices (H_2O: 3.05 um, CO_2: 4.27 um, and XCN: 4.62 um) and the
emission of polycyclic aromatic hydrocarbons (PAHs) at 3.29 um and hydrogen
recombination line Br alpha at 4.05 um. We find that the distributions of the
ices differ from those of the PAH and gas. We calculate the column densities of
the ices and derive the abundance ratios of N(CO_2)/N(H_2O) = 0.17 +- 0.05.
They are similar to those obtained around the massive young stellar objects in
our Galaxy (0.17 +- 0.03), although much stronger interstellar radiation field
and higher dust temperature are expected near the center of NGC253.
