High-resolution CO images of the Galactic central molecular zone

Sekito Tokuyama, Tomoharu Oka, Shunya Takekawa, Yuhei Iwata, Shiho Tsujimoto, Masaya Yamada, Maiko Furusawa, Mariko Nomura

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15 Citations (Scopus)


We performed Nyquist-sampled mapping observations of the central molecular zone of our Galaxy in the J = 1-0 lines of CO, 13CO, and C18O using the 45 m telescope at the Nobeyama Radio Observatory. The newly obtained data sets were an improvement by a factor of four in spatial resolution of the CO data previously obtained with the same telescope 22 years ago, providing the highest angular resolution CO atlas of this special area of the Galaxy. The data cover the area: -0${^{\circ}_{.}}$8 ≤ l ≤ +1${^{\circ}_{.}}$4 and -0${^{\circ}_{.}}$35 ≤ b ≤ +0${^{\circ}_{.}}$35 with a 15″ beamwidth. Total intensity ratios for CO J = 3-2/J = 1-0, 13CO/CO J = 1-0 and C18O/13CO J = 1-0, are 0.70 ± 0.06, 0.12 ± 0.01, and 0.14 ± 0.01, respectively. The high-resolution CO images show the fine structure of the molecular gas and enable us to identify a number of compact clouds with broad velocity widths, i.e., high-velocity compact clouds. We conducted a detailed comparison of our CO J = 1-0 data with the CO J = 3-2 data obtained with the James Clerk Maxwell Telescope to derive the distribution and kinematics of the highly excited gas. Three, out of four, of the previously identified high CO J = 3-2/J = 1-0 ratio areas at l = +1${^{\circ}_{.}}$3, 0${^{\circ}_{.}}$0, and -0${^{\circ}_{.}}$4 were confirmed with a higher spatial resolution. In addition to these, we identified several very compact, high CO J = 3-2/J = 1-0 spots with broad velocity widths for the first time. These are candidates for accelerated gas in the vicinity of invisible, point-like massive objects.

Original languageEnglish
Article numberS19
JournalPublications of the Astronomical Society of Japan
Publication statusPublished - 2019 Dec 1


  • Galaxy: center
  • Galaxy: kinematics and dynamics
  • ISM: molecules
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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