The structure and star-forming fate of the Galactic centre cloud G0.253+0.016 Katharine Johnston MPIA, Heidelberg, DE
The massive infrared dark cloud G0.253+0.016 projected 45pc from the Galactic centre contains 105 Msun of dense gas whilst being mostly devoid of observed star formation tracers. To scrutinise the gas properties of G0.253+0.016, we have carried out a concerted SMA and IRAM 30m study of this enigmatic cloud in dust continuum, CO isotopologues as low-density tracers, as well as CH3OH and SiO as shock tracers. In this talk, I will firstly discuss in detail the density structure of the cloud traced by column density PDFs and delta-variance spectra, with relation to whether star formation is currently ongoing. I will then show how our observations suggest that G0.253+0.016 is colliding with another cloud - in fact, this may have been the formation scenario for G0.253+0.016. The collision will also likely affect its structure, internal turbulence, and final star-forming fate. I will finally discuss how G0.253+0.016 fits into our picture of the dynamics and geometry of the Galactic centre region. Specifically, I will show that the model of the 100pc Galactic centre ring suggested by Herschel Hi-Gal observations does not explain the observed longitude-velocity diagrams of recent molecular line surveys of the CMZ, and thus a different orientation and/or geometry is required.
Caption: Left panel: Map of the SMA 230.9GHz / 1.30mm continuum emission. Right panel: Combined SMA 1.3mm and SCUBA 450 micron image (scaled via fits to Herschel Hi-Gal data), recovering a large range of structures in the cloud.
Collaborators: H. Beuther, MPIA, Germany H. Linz, MPIA, Germany A. Schmiedeke, U Koeln, Germany S. Longmore, Liverpool JMU, UK J. Rathborne, CSIRO, Australia S. Ragan, MPIA, Germany	Suggested Session: Molecular Clouds