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Abstract The central 5 pc of our Galactic center is rich in various molecular tracers. The region is observed to be hot, highly ionized, and volatile, resulting in complex chemistry and kinematics. Countless molecular observations of the central region orbiting the central supermassive black hole Sgr A*have revealed a stable grouping of clouds with a disklike structure known as the circumnuclear disk (CND) orbiting Sgr A*between 1.5 and 3 pc. The CND houses the densest population of gas outside the ionized streams in the minispiral falling onto Sgr A*. However, the small-scale kinematics of the clouds and gas are poorly understood in this region. In this paper, we report single-dish SiO (1–0) observations of the central 5 pc surrounding Sgr A*taken with the Green Bank Telescope. Most of the SiO (1–0) traces the Southern Streamer and Sgr A East—neither of which are associated with the CND. However, one region in the CND, known as the Northeast (NE) Arm, shows high-intensity SiO emission unlike in the rest of the CND, indicating the NE Arm as a candidate region of either cloud–cloud collision or early star formation. Further high-resolution observations of the region are needed to distinguish between the two scenarios.
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This content will become publicly available on April 15, 2027
Reconciling 3D Models for the Central 10 pc of the Milky Way
Abstract The construction of an accurate 3D model of the Milky Way center is necessary to understand inflow processes that drive its overall evolution and to compare our Galactic nucleus to other galaxies’ nuclei. A main point of contention is the line-of-sight location of sources observed toward the central 10 pc of the Galaxy, including recent star formation (the Sgr A East supernova remnant and Sgr A HIIregions) and copious gas (the 50 and 20 km s−1molecular clouds, the circumnuclear disk, and the Sgr A West ionized “minispiral” that encircles the central supermassive black hole, Sgr A*). Some models place all of these structures within a radius of 5 pc from Sgr A*, while others place the 20 and 50 km s−1clouds at a distance of at least 30−50 pc away from Sgr A* along the line of sight. We present new radio and millimeter observations of the molecular gas toward the central ∼10 pc, from which we have constructed an alternative 3D model that is consistent with both prior radio observations and orbital gas kinematics. Our model places the 20 km s−1cloud, 50 km s−1cloud, and Sgr A East more than 10 pc in front of Sgr A*. While this model does not conclusively rule out a connection between the 50 and 20 km s−1clouds and the circumnuclear disk, we argue that prior evidence for these connections is tenuous, especially given the complex spatial and kinematic overlap of structures along the line of sight.
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- PAR ID:
- 10680336
- Publisher / Repository:
- The Astrophysical Journal
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 1001
- Issue:
- 2
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 184
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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