sentence: Most galaxies are believed to have a supermassive black hole at their center.
sentences_before: Movement of material around the galactic center shows that it has a compact object of very large mass.
sentences_after: Blandford R.D. 1999. Origin and evolution of massive black holes in galactic nuclei. In 'Galaxy Dynamics', ASP Conference Series vol.
concept_name: galaxy
headings: Milky Way Galactic center
categories: Spiral galaxies Local galaxies