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Title: DIFFERENCE IN THE SPATIAL DISTRIBUTION BETWEEN H{sub 2}O AND CO{sub 2} ICES IN M 82 FOUND WITH AKARI

With AKARI, we obtain the spatially resolved near-infrared (NIR) (2.5-5.0 {mu}m) 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 H{sub 2}O and CO{sub 2} ices. As a result, we find that the spatial distribution of H{sub 2}O ice is significantly different from that of CO{sub 2} ice; H{sub 2}O ice is widely distributed, while CO{sub 2} ice is concentrated near the galactic center. Our result reveals for the first time variations in CO{sub 2}/H{sub 2}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 Br{alpha} and Br{beta} lines and the polycyclic aromatic hydrocarbon 3.3 {mu}m emission appearing in the AKARI NIR spectra.
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
  2. Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  3. Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501 (Japan)
  4. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Chuo-ku, Sagamihara 252-5210 (Japan)
  5. Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong, Daejeon 305-348 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22136563
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 773; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABUNDANCE; CARBON DIOXIDE; DENSITY; EMISSION SPECTRA; GALAXIES; HYDROGEN; ICE; POLYCYCLIC AROMATIC HYDROCARBONS; RECOMBINATION; SPATIAL DISTRIBUTION; WATER