Observations from a black hole called 1ES 1927+654 in which x-ray flashes increased in frequency from every 18 minutes to every seven minutes were examined by researchers.
Over a two-year period the frequency of these flares increased, suggesting the object orbiting the black hole - believed to be a white dwarf - was moving faster as it moved closer to the event horizon, thus increasing the frequency of the x-ray emissions.
White dwarfs are the cores of dead stars and are extremely dense, meaning if the theory is correct it would be the closest object to a black hole that has ever been observed.
It is also expected that the white dwarf would give off gravitational waves as it orbits, which could be detectable by the Laser Interferometer Space Antenna (LISA) - due for launch in the mid-2030s.