2002/07/26 by Kim Sung-Eun, Sungeun Kim, Kim, Sungeun +8
Chemistry · Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #Atomic and Molecular Physics #FOS: Physical sciences #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0207586
20 pages, 6 figures, Appear to v580 n2 ApJ December 1, 2002 issue, uncompressed figures are available at http://cfa-www.harvard.edu/~skim
openalex publication_date 2002/07/26 · arxiv created 2002/08/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present position-velocity strip maps of the Galactic Center region in the\nCO J=7-6 and J=4-3 transitions observed with the Antarctic Submillimeter\nTelescope and Remote Observatory (AST/RO) located at Amundsen-Scott South Pole\nStation. Emission from the two rotational transitions of 12CO was mapped at\nb=0 deg for 3.5 deg > l > -1.5 deg, on a 1' grid with a FWHM beamsize of 58''\nat 806 GHz and 105'' at 461 GHz. Previous observations of CO J=4-3 (Martin et\nal., in preparation) and CI (Ojha et al. 2001) emission from this region show\nthat these lines are distributed in a manner similar to CO J=1-0 (Stark et al.\n1987); the (CO J=4-3)/(CO J=1-0) line ratio map is almost featureless across\nthe entire Galactic Center region. In contrast, the CO J=7-6 emission from the\nGalactic Center is strongly peaked toward the Sgr A and Sgr B molecular\ncomplexes. A Large Velocity Gradient (LVG) analysis shows that aside from the\ntwo special regions Sgr A and Sgr B, the photon-dominated regions within a few\nhundred parsecs of the Galactic Center are remarkably uniform in mean density\nand kinetic temperature at n = 2500 to 4000 cm-3 and T=30 to 45K. The (CO\nJ=7-6)/(CO J=4-3) line temperature ratios near Sgr B are a factor of two higher\nthan those observed in the nuclear region of the starburst galaxy M82 (Mao et\nal. 2000), while the CO(J=7-6)/CO(J=4-3) line temperature ratios around Sgr A\nare similar to M82. The line ratio on large scales from the Galactic Center\nregion is an order of magnitude less than that from M82.\n