Going beyond cloud segmentation: Unveiling the detailed velocity structure of the CO gas in the Galactic plane
Manuel Riener
Thursday December 5th, 09:00
For decades, the analysis of molecular gas structures in the Galactic plane has been driven by segmentation approaches based on ""cloud-finding"" or ""clump-finding"". While these works have been important for quantifying the mean properties of cloud-like structures, the cloud-based analysis by design washes away important information about the detailed, internal velocity structure of the gas both inside the clouds and at Galactic scales. This velocity structure thus still largely remains unexplored and unknown, also because of the technical challenge of efficiently dealing with hundreds of thousands of velocity components. We have recently worked on developing an automated Gaussian decomposition scheme that incorporates a machine-learning approach to automatically fit hundreds of thousands of spectra and velocity components. Combined with a Bayesian approach of determining distances to the identified components, this enables us to look for systematic trends that are directly linked to the physical processes in the gas (e.g., fluctuation patterns in the velocity field due to instabilities and/or turbulence, shear, Galactic potential, or kinematic effects of spiral arms). Our new analysis focusses in particular on differences in the turbulent velocity structure of molecular clouds across Galactic environments and may thus give insight to the universality of the turbulent velocity fluctuations that we see in the observations. In this contribution, I will present the first results of our work on the Galactic Ring Survey and describe its synergy with SEDIGISM, a new CO survey of the Galactic plane in the fourth quadrant.