A molecular cloud and an expanding cavity adjacent to the nonthermal filaments of the Galactic center radio arc

Tomoharu Oka, Tetsuo Hasegawa, Fumio Sato, Masato Tsuboi, Atsushi Miyazaki

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Large-scale CO images taken with the 2 × 2 focal-plane array receiver on the 45 m telescope of Nobeyama Radio Observatory reveal parsec-scale structure of molecular gas around the Galactic center radio arc. The LVG analysis shows that the gas kinetic temperature is considerably enhanced (Tk ≥ 70K) in CO 0.13-0.13, a cloud which seems to be in contact with the nonthermal filaments of the Galactic center radio arc. This lends support for an interaction between CO 0.13-0.13 and the nonthermal filaments. The interaction with the strong magnetic field in and around the nonthermal filaments may heat up the molecular gas in CO 0.13-0.13 through shock dissipation and/or magnetic viscosity. We also find an expanding cavity adjacent to the nonthermal filaments. The shell has a radius of ∼ 5 pc and an expansion velocity of 25kms-1. This expanding cavity might have been formed by several hundred supernovae or a single hypernova within 3 × 105 yr. Magnetic tubes in this region could have been swept up by the expanding cavity, and compressed by interactions with CO 0.13-0.13. An interaction between the cloud and magnetic field may accelerate electrons to relativistic energies through shock acceleration or magnetic field reconnection.

Original languageEnglish
Pages (from-to)779-786
Number of pages8
JournalPublications of the Astronomical Society of Japan
Issue number5
Publication statusPublished - 2001 Oct 25



  • Galaxies: nuclei
  • Galaxy: center
  • ISM: clouds
  • ISM: molecules

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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