Astronomers have detected what they believe is the long-sought radio emission coming from a supermassive black hole at the center of one of our closest neighboring galaxies, using the Karl G. Jansky Very Large Array (VLA).
The elliptical galaxy, called Messier 32 (M32), with little star formation is a satellite of the Andromeda Galaxy, our own Milky Way’s giant neighbor. About 2.5 million light-years from Earth, M32 is much smaller than either the Milky Way or Andromeda.
Supermassive black holes are found at the cores of most galaxies, and as those black holes draw in matter from their surroundings, jets of material propelled to speeds close to that of light by the black holes often generate radio waves detectable with radio telescopes.
The intensity of this radio emission depends on how voraciously the black hole is consuming surrounding matter. The central black holes of the Milky Way and Andromeda are quite weak radio emitters compared to many other galaxies.
Nanjing University’s Yang Yang said that the very faint radio emission, which they think is coming from M32’s central black hole, indicates that this object’s activity is among the weakest yet found, along with the Milky Way and Andromeda, adding that studying such quiescent black holes gives them an excellent opportunity to advance our presently-poor understanding of their physics.
The VLA image showed a faint radio-emitting object at the location where X-rays are being emitted and around which stars near the galaxy’s center appear to be orbiting. This tells the researchers that the radio emission most likely is coming from the black hole, but they want to do further observations to confirm this, Yang said.