bunsen_h: (Popperi)
[personal profile] bunsen_h
The CBC just reported the discovery of a supermassive black hole, of the kind that usually sits at the center of a galaxy, travelling at extremely high speed away from its galaxy.  It's believed to be the result of the merger of two galaxies, with their respective central black holes merging and being flung away.

My intuition explains this as being somewhat like the old children's game "Battling Tops".  In that game, players launch small spinning tops towards each other in a bowl-shaped "arena".  The tops are spinning in the same direction, so at the point of contact, the rims are moving in opposite directions.  The collision transfers some of the rotational momentum of the spins to the tops with respect to each other, slowing the spins and kicking the tops away from each other.  Eventually, the tops slide down the bowl again, and after a few collisions, at least one gets knocked over; the winning player is the one whose top is standing last.

With the black holes, getting flung away from each other after "contact" doesn't work so well.  So a massive pulse of gravitational wave energy gets flung in one direction, and the merged black hole heads in the opposite direction.

Or so my intuition says.  Dammit, I'm a doctor of chemistry, not a doctor of astrophysics.

Date: 2017-04-02 01:33 am (UTC)
From: [identity profile] dewline.livejournal.com
Which leaves me wondering about one thing:

Did that collision and the sequelae as you describe them above trigger the destruction of all life as we might have hoped to know it in those galaxies?

My gut says the answer should be "yes". :-(

Date: 2017-04-02 04:48 pm (UTC)
From: [identity profile] bunsen-h.livejournal.com
The article quotes "Black hole expert Harald Pfeiffer, from the University of Toronto's Canadian Institute for Theoretical Astrophysics" as saying: "Not only we are safe, but probably all the aliens in that other galaxy are also quite safe." Because space is really really big, and the speeding supermassive black hole isn't likely to hit anything.

But clearly that doesn't help anyone living near the path of the black hole in the pile-up of stars resulting from its original two galaxies which merged. And I don't know what effect there might be from the pulse of gravitational wave energy in the opposite direction. Mind you, it's possible that the effects of merging the two galaxies would have been disastrous for a large fraction of the people living there, so the black hole and the gravitational wave pulse would have been just icing on the cake, as it were. ("Disaster" = "bad" + "star", incidentally.) Apart from perturbation of orbits of bodies, the collision of the gas clouds could have warmed things up considerably.

June 2017


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