Catalog of High-velocity Dispersion Compact Clouds in the Central Molecular Zone of Our Galaxy

Abstract

This study developed an automated identification procedure for compact clouds with broad velocity widths in the spectral-line data cubes of highly crowded regions. The procedure was applied to the CO J = 3 − 2 line data, obtained using the James Clerk Maxwell Telescope, to identify 184 high-velocity dispersion compact clouds (HVDCCs), which are a category of peculiar molecular clouds found in the central molecular zone of our Galaxy. A list of HVDCCs in the area −1.°4 ≤ l ≤ +2.°0, −0.°25 ≤ b ≤ +0.°25 was presented with their physical parameters, CO J = 3 − 2/J = 1 − 0 intensity ratios, and morphological classifications. Consequently, the list provides several intriguing sources that may have been driven by encounters with pointlike massive objects, local energetic events, or cloud-to-cloud collisions.

ALMA View of the High-velocity-dispersion Compact Cloud CO 0.02–0.02 at the Galactic Center

“…The molecular gas in the CMZ is higher in temperature and density than in the Galactic disk, showing highly complex distribution and kinematics. High-velocity-dispersion compact clouds are a peculiar population of molecular clouds found in the CMZ (Oka et al 1998(Oka et al , 2022. They are characterized by their compact appearance (d < 5 pc) and unusually large velocity widths (ΔV > 50 km s −1 ).…”

Discovery of the Tadpole Molecular Cloud near the Galactic Nucleus

“…In the central molecular zone (CMZ) of our Galaxy, a number of compact (d < 5 pc) clouds with extraordinary broad velocity width (ΔV > 50 km s −1 ) have been detected (e.g., Oka et al 1998Oka et al , 1999Oka et al , 2012Oka et al , 2022. These peculiar clouds, namely, high-velocity-dispersion compact clouds (HVCCs), have been assumed to be accelerated by supernova explosions, protostellar outflows, and/or cloud-to-cloud collisions (e.g., Oka et al 2022).…”

“…In the central molecular zone (CMZ) of our Galaxy, a number of compact (d < 5 pc) clouds with extraordinary broad velocity width (ΔV > 50 km s −1 ) have been detected (e.g., Oka et al 1998Oka et al , 1999Oka et al , 2012Oka et al , 2022. These peculiar clouds, namely, high-velocity-dispersion compact clouds (HVCCs), have been assumed to be accelerated by supernova explosions, protostellar outflows, and/or cloud-to-cloud collisions (e.g., Oka et al 2022). Subsequently, it was determined that the kinematics of CO-0.40-0.22, which is one of the most energetic HVCCs, can be well reproduced by a cloud being gravitationally kicked by a point-like mass of ∼10 5 M e (Oka et al 2016(Oka et al , 2017.…”

“…014), which corresponds to ∼2 6 Galactic northwest of Sgr A * (Figure 1), with LSR velocities between −140 and −90 km s −1 . It stands out with its peculiar appearance and very high CO J = 3-2/CO J = 1-0 intensity ratio (R 3-2/1-0 = 1.8 Oka et al 2022), which exceeds double of the CMZ average (R 3-2/1-0 ∼ 0.7 Oka et al 2007Oka et al , 2012. In this paper, we report the discovery of the socalled "Tadpole" molecular cloud, which is listed as id.75 in the catalog of Oka et al (2022).…”

“…It stands out with its peculiar appearance and very high CO J = 3-2/CO J = 1-0 intensity ratio (R 3-2/1-0 = 1.8 Oka et al 2022), which exceeds double of the CMZ average (R 3-2/1-0 ∼ 0.7 Oka et al 2007Oka et al , 2012. In this paper, we report the discovery of the socalled "Tadpole" molecular cloud, which is listed as id.75 in the catalog of Oka et al (2022). Throughout this paper, the distance to the Galactic center is assumed to be D = 8.3 kpc (Gravity Collaboration et al 2018).…”