SIMBAD references

With AKARI, we obtain the spatially resolved near-infrared (NIR) (2.5-5.0 µm) spectra for the nearby starburst galaxy M 82. These spectra clearly show absorption features due to interstellar ices. Based on the spectra, we created the column density maps of H₂ O and CO₂ices. As a result, we find that the spatial distribution of H₂ O ice is significantly different from that of CO₂ice; H₂ O ice is widely distributed, while CO₂ice is concentrated near the galactic center. Our result reveals for the first time variations in CO₂/H₂ O ice abundance ratio on a galactic scale, suggesting that an ice-forming interstellar environment changes within a galaxy. We discuss the cause of the spatial variations in the ice abundance ratio, utilizing spectral information on the hydrogen recombination Brα and Brβ lines and the polycyclic aromatic hydrocarbon 3.3 µm emission appearing in the AKARI NIR spectra.