The research into the nature and properties of the black hole at the centre of the Milky Way galaxy is one of the highlights of astronomical discovery of the last two decades. Using the biggest telescopes on the planet and state of the art observing technology, we’ve been able to track the young massive stars that are whizzing around the black hole in a dense cluster, and shown with a high level of certainty that the galaxy’s central object really is a supermassive black hole, referred to as Sagittarius A*. Using these stellar orbits, we’ve also determined its mass – 4 million solar masses.

Now you see it, now you don't! The square arcsecond surrounding the galactic centre black hole, seen in the near-infrared. On the left, no source is visible, later on (right) a flare brought it into view. The star marked S2 is the closest known star to Sgr A*. Click to embiggen. (ESO)

With the next generation of infrared instrumentation, we’re planning to take the next step in the study of Sgr A*. For this, we’ll use interferometry – the combination of light beams from a number of telescopes – to zoom into the black hole closer than ever before. In a paper posted to the Arxiv late last year, Vincent et al discuss the potential of a new interferometric instrument, Gravity, for testing black hole physics near Sgr A*.

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