Dario Colombo (MPIfR): Building a (fully resolved) molecular cloud catalog of the Milky Way

Seminar | March 13 | 3:10-4 p.m. | 131 Campbell Hall

 Dario Colombo, Max Planck Institute for Radio Astronomy

 Radio Astronomy Lab

Modern high resolution, molecular gas surveys of the Galactic Plane are unveiling an astonishing picture of the three-dimensional gas organization of the Milky Way. This provides the opportunity to investigate the building blocks of the molecular medium, the Giant Molecular Clouds (GMCs), in an unprecedented level of detail. So far, however, such kind of study has been restricted to a handful of isolated targets, since common automatic segmentation methods, being severely affected by survey designs, are unable to decompose GMC-sized objects out from the diffuse medium in crowded Galactic regions. The algorithm we designed, SCIMES (Spectral Clustering for Interstellar Molecular Emission Segmentation), overcomes these limitations by considering the cloud segmentation problem in the broad framework of the graph theory. To prove this, we will present the SCIMES cloud catalog from the CO(3-2) High-Resolution Survey (COHRS) data. The clustering approach allows to automatically identify a variety of gas morphologies including coherent filaments and holes within the molecular interstellar medium. We will show how star formation efficiency, turbulence, and kinematics vary within those gas structures and with respect to the Galactic environments. Together, we will related the integrated properties of COHRS objects to the ones observed for molecular clouds in other regions of the Milky Way and nearby galaxies. This pioneer study will provide the guidelines for a future, systematic cataloging of all discrete molecular gas features of our own Galaxy.