AKARI Near-Infrared Spectroscopic Observations of Interstellar Ices in Edge-on Starburst Galaxy NGC253

Abstract

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.

12 pages, 4 figures, accepted for publication in the ApJ Letters

References in corpus (3)

• The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects II: CO2
• AKARI Near Infrared Spectroscopy: Detection of H2O and CO2 Ices toward Young Stellar Objects in the Large Magellanic Cloud
• Ice chemistry in massive Young Stellar Objects: the role of metallicity

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• VLT/ISAAC infrared spectroscopy of embedded high-mass YSOs in the Large Magellanic Cloud: Methanol and the 3.47 micron band
• A relation of the PAH 3.3 um feature with star-forming activity for galaxies with a wide range of infrared luminosity
• A Molecular Line Survey toward the Nearby Galaxies NGC 1068, NGC 253, and IC 342 at 3 mm with the Nobeyama 45-m Radio Telescope: Impact of an AGN on 1 kpc Scale Molecular Abundances
• The Near-Infrared CO Absorption Band as a Probe to the Innermost Part of an AGN Obscuring Material
• Two dimensional ice mapping of molecular cores
• Processing of polycyclic aromatic hydrocarbons in molecular-loop regions near the Galactic center revealed by AKARI
• Difference in the spatial distribution between H_2O and CO_2 ices in M82 found with AKARI
• Mapping Interstellar Ice Inventory toward Class 0 Protostars in Star-forming Region Orion A with JWST Data