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Hidehiro Kaneda, Daisuke Ishihara, Akio Mouri, Shinki Oyabu, Mitsuyoshi Yamagishi, Toru Kondo, Takashi Onaka, Yasuo Fukui, Akiko Kawamura, Kazufumi Torii, Processing of Polycyclic Aromatic Hydrocarbons in Molecular-Loop Regions near the Galactic Center Revealed by AKARI, Publications of the Astronomical Society of Japan, Volume 64, Issue 2, 25 April 2012, 25, https://doi.org/10.1093/pasj/64.2.25
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Abstract
We present an AKARI mid-infrared diffuse map of an area of about 4|$^{\circ}$||$\times$| 3|$^{\circ}$| 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 |$\sim$| 2|$^\circ\!\!\!.$|5, which have spatial correspondence to molecular loops revealed by NANTEN |$^{12}$|CO (|$J$||$=$| 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.
