True, some black holes have extreme magnetic fields and astronomical objects that have a changing magnetic field can produce radio waves.
It can be a neutron star as well, a magnetar, like
this one astronomers found year ago.
Thinking about it, that source can actually be several sources.
Imagine a magnetar or similar star with jets, tumbling chaotically around its tight orbit around the black hole as it spirals inwards. We'd see those jets erratically while it's in view, but not when it's round the other side of the BH, perhaps for weeks or months at a time due to its gigantic size. Meanwhile there are other sources getting tossed around there, leading to the chaotic signal that we see. If only we could send a probe there, sigh. Or a manned mission for the drama, kept track of in a series of programs. It would beat all ratings ever...
Another thing I've been thinking of is the unbridled power of a black hole.
Imagine a neutron star, one of the heaviest and most deadly objects in the universe. Just 15 miles across, immense gravity, brighter than thousands of stars, with unimaginable solar winds and intense swirling magnetic fields. Nothing can touch it. Except a black hole. Imagine this thing is heading straight for our supermassive black hole. Since its diameter is so immense (light minutes across) the tidal forces on the neutron star will be very low. When it eventually hits the event horizon at some significant fraction of the speed of light, it will just plop inside without even a whimper. Nothing. No explosion, no heat, no radiation. From our point of view, it will simply quietly fade out of existence. Something that can do that to it, now
that's power!
I'd love to know how the now raging star is torn apart once it's inside that event horizon and eventually smashes into the singularity - and at what speed. Colossal doesn't begin to describe it.