This is one of those cases in science where the absence of a discovery is the significant scientific discovery!
This is about an observed supper-massive galaxy in a middle of a huge galaxy cluster that, as a result of our current understanding of black holes in galaxies, we would thus expect to have a super-massive black hole in its core and yet, despite a long and exhaustive search for just such a black hole, none was found thus indicating that, mysteriously, this super-massive galaxy has none!
And nobody is sure why! Although there has been some suggestion that millions of years ago something (what?) had somehow (how?) dragged out the back hole out of this galaxy, there are various problems with this suggestion. It is just as if it once had a back hole millions of years ago but then that black hole for some yet unknown reason just suddenly mysteriously vanished!
And, to further deepen this mystery, unlike the core of other galaxies, the core of this galaxy becomes less dense, not more dense, towards its center. And nobody is sure why of that either. It is just as if something blasted most of the mass of the center of its core, including its black hole, clean away from the galaxy to god knows where.
I for one would be interesting to find out what will be the truth eventually discovered to solve this mystery and I hope I will live long enough to find out.
@humy saidI have just had a thought about that;
It is just as if it once had a back hole millions of years ago but then that black hole for some yet unknown reason just suddenly mysteriously vanished!
This is admittedly just wild layperson speculation on my part but, perhaps an explanation could be that there is a size limit on how big a black hole can get and if it reaches that size limit, the gravity becomes SO stupendous that the black hole becomes unstable and then collapses in on itself to perhaps enter another dimension and exit out of our universe thus literally ceases to exist in our universe!?
If that wild hypothesis is true, the black hole really DID suddenly just simply vanish from that galaxy some millions of years ago!
Any general relativity experts here like to comment on what they think of that idea?
@humy
Well that thing could be evidence for the idea that the other end of a black hole is the inception of a daughter universe.
That would be very interesting if more evidence was found.
It might also just be the black hole ran out of stuff to grab and is sitting in open space with nothing much around it and the gravitational lensing maybe not seen because of nothing much visible behind it to make for Einstein rings.
@sonhouse saidThe density of the galactic core seems to indicate its absence. What could happen is a fast moving supermassive black hole collided with the central black hole, they merged and had sufficient residual velocity to leave the galaxy. However, one would expect a trail of stars.
@humy
Well that thing could be evidence for the idea that the other end of a black hole is the inception of a daughter universe.
That would be very interesting if more evidence was found.
It might also just be the black hole ran out of stuff to grab and is sitting in open space with nothing much around it and the gravitational lensing maybe not seen because of nothing much visible behind it to make for Einstein rings.
I just found this video about yet another mysterious observation, this time of a galaxy currently in the process of losing much of its mass but we aren't sure what is causing it to lose so much mass because its central black hole activity cannot account for most of that mass lose and it seems to be losing mass as a huge rate that is so high that its not easily explained;
Makes me wonder if the OP galaxy lost its central black hole by the same kind of unknown thing, whatever that unknown thing is, that is causing this more recently observed galaxy to be currently losing much of its mass.
@humy
So if your idea of it getting ejected is right, maybe the ejecta went straight up out of the plane of the galaxy so there would not be much in the way of stars pulled out with the central black hole.
The only way we could detect an isolani like that would be the gravitational lensing it would do to galaxies behind it.