The Galactic center region
High angular resolution radio interferometry at high frequencies enables us to study in great detail the emission mechanisms of the central region of our Galaxy, which harbours the supermassive black hole source Sagittarius A*. This talk will focus on recent results from our observations with two radio interferometer arrays, the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and Australia Telescope Compact Array (ATCA), and the infrared Very Large Telescope (VLT). I will also present results from the flare modelling of Sgr A* based on multi-wavelength observing campaigns, along with high-resolution maps and a spectral index analysis of the extended emission of the central region (the "mini-spiral") at 3 and 1.3 mm, and compare them to maps in near-infrared Br-gamma (2.16 micron) and mid-indfrared (8.6 micron) wavelengths. I will discuss physical properties of gas and dust that can be deduced from these measurements, such as spectral index, emission measure, density, mass, and extinction.