The Milky Way galaxy, like most large galaxies, has a supermassive black hole at its center, but some galaxies are centered on lighter, intermediate-mass black holes. RX J1140.1+0307 is such a galaxy—in fact, it is centered on one of the lowest black hole masses known in any luminous galactic core.

What puzzles scientists about this particular galaxy is that the calculations don't add up. With such a relatively low mass for the central black hole, models for the emission from the object cannot explain the observed spectrum.

There must be other mechanisms at play in the interactions between the inner and outer parts of the accretion disk surrounding the black hole. European Space Agency

Read more at: https://phys.org/news/2017-01-hubble-black-hole-puzzling.html#jCp