Despite their importance as stellar nurseries and the building blocks of galaxies , very little is known about the formation of the highest mass clusters .
The dense clump G0.253+0.016 represents an example of a clump that may form an Arches-like , high-mass cluster .
Here we present molecular line maps toward G0.253+0.016 taken as part of the MALT90 molecular line survey , complemented with APEX observations .
Combined , these data reveal the global physical properties and kinematics of G0.253+0.016 .
Recent Herschel data show that while the dust temperature is low ( \sim 19 K ) toward its centre , the dust temperature on the exterior is higher ( \sim 27 K ) due to external heating .
Our new molecular line data reveal that , overall , the morphology of dense gas detected toward G0.253+0.016 matches very well its IR extinction and dust continuum emission .
An anti-correlation between the dust and gas column densities toward its centre indicates that the clump is centrally condensed with a cold , dense interior in which the molecular gas is chemically depleted .
The velocity field shows a strong gradient along the clump ’ s major axis , with the blue-shifted side at higher Galactic longitude .
The optically thick gas tracers are systematically red-shifted with respect to the optically thin and hot gas tracers , indicating radial motions .
The gas kinematics and line ratios support the recently proposed scenario in which G0.253+0.016 results from a tidal compression during a recent pericentre passage near SgrA ^ { * } .
Because G0.253+0.016 represents an excellent example of a clump that may form a high-mass cluster , its detailed study should reveal a wealth of knowledge about the early stages of cluster formation .