Room by Kerry Hebden 12/17/2021
By making the most precise measurements yet of the motions of stars around Sagittarius A*, the supermassive black hole at the centre of the Milky Way, astronomers have calculated that a staggering 99.9 percent of the mass contained at the very center of the galaxy is due to the black hole, and only 0.1 percent could include stars, smaller black holes, interstellar dust and gas, or dark matter.
Located roughly 27,000 light-years from the Sun, the centre of our galaxy is dominated by a supermassive black hole 4.3 million times as massive as the Sun.
Although scientists had long suspected that this compact radio source, known as Sagittarius A* or Sgr A* for short, was indeed a black hole, it was only after years of painstaking observations of the motion of stars around Sgr A* that led to confirmation that the black hole existed. This pioneering work was led by groups headed by Reinhard Genzel and Andrea Ghez, and their efforts won the duo half a Nobel Prize in Physics in 2020.
Since then, Genzel and colleagues have been working on confirming more details about Sgr A*, specifically, is general relativity indeed the correct theory of gravity in this extreme laboratory, and is there anything else hidden at the centre of the Milky Way.
More:
https://room.eu.com/news/new-study-shows-that-999-of-the-mass-at-the-centre-of-our-galaxy-is-due-to-black-hole
