Processing of Polycyclic Aromatic Hydrocarbons in Molecular-Loop Regions near the Galactic Center Revealed by AKARI

作者：Kaneda Hidehiro^*; Ishihara Daisuke; Mouri Akio; Oyabu Shinki; Yamagishi Mitsuyoshi; Kondo Toru; Onaka Takashi; Fukui Yasuo; Kawamura Akiko; Torii Kazufumi

来源：Publications of the Astronomical Society of Japan, 2012, 64(2): 251-259.

DOI：10.1093/pasj/64.2.25

• infrared: general
• infrared: ISM
• ISM: dust, extinction
• ISM: lines and bands
• ISM: molecules
• ISM: structure

We present an AKARI mid-infrared diffuse map of an area of about 4 degrees x 3 degrees near the Galactic center in the 9 mu m band. The band intensity is mostly attributed to aromatic hydrocarbon infrared emissions of carbonaceous grains at wavelengths of 6.2, 7,7, 8.6, and 11.3 mu m. We detected 9 mu m emission structures extending from the Galactic plane up to a latitude of similar to 2 degrees.5, which have spatial correspondence to molecular loops revealed by NANTEN (CO)-C-12 (J = 1-0) observations. We have found that the surface brightness at 9 mu m is suppressed near the foot points of the CO loops. The ratios of the 9 mu m to the IRAS 100 mu m brightness show significant depression near such bright regions in CO emission. With AKARI near-infrared 2.5-5 mu m spectroscopy, we find that the 3.3 mu m aromatic hydrocarbon emission is absent in the region associated with the loop, suggesting the processing and destruction of carbonaceous grains in the CO molecular loops.

• 出版日期2012-4-25