Here is a bit more on where and what they used to come to this conclusion:

A new discovery, published in the journal Science, has greatly deepened our understanding black holes, which are believed to be the gravitational engines at the centres of most galaxies, including our own.

Using an array of telescopes that spans the globe, astronomers detected evidence of magnetic fields near Sagittarius A*, the 4.5-million-solar-mass black hole at the centre of the Milky Way.

Now that this international collaboration has discovered high levels of polarization in the radio emissions from Sagittarius A*, physicists have proof that these magnetic fields indeed exist.

What do you think they will find when these even larger telescopes come online?

Feel free to comment with your ideas!

thanks to premierinstitute.ca for the great info