In a place where millions of galaxies reside, collisions are inevitable. With my age parallel to the age of universe itself, I suppose it is safe to assume that I have witnessed collisions in the large variety that they occur.
Few are customary greetings as the galaxies pass by each other, where the larger one gobbles up the tiny, more vulnerable galaxy. Neat. Effortless. Terrifying. One moment it is there, the other it isn’t. Then there are these more disrupting, heart-wrenching collisions. The bigger, more massive galaxies lock horns in a deadly cosmic dance. It is a pity that such beautiful profiles have to distort themselves only to merge and quieten down after a while. There is nothing I can do to stop these headlong crashes the galaxies seem to take a liking to. Try as I might, gravity of these galaxies often dominates my mission to pull them apart, and they end up gravitating towards each other. It is part of their evolution, I suppose, as is mine, to keep growing, expanding, accelerating.
Then there is the Milky Way and Andromeda. Oh boy, wouldn’t that be a sight worth looking out for. Being the largest galaxies in the local group with fierce black holes at each of their centers, their collision is bound to get a lot of attention. It is still a wonder to me how gravity manages to tug them together while I, at all times, work on increasing the distance between them.
They will eventually come in the vicinity of each other. And when they do,all hell will break loose. Their arms will reach out to greet each other, or so I’d like to think, but it will really be the tidal force sneaking in for its share of fun. Stars loosely bound to the galaxy’s centers shall eagerly swap homes, ready to abandon their places. The gravity never took them seriously anyway. The galaxies’ arms will then connect in a slow, lazy way.
Stellar Trails. nd. fromquarkstoquasars.com. Web. 17 Feb. 2018.
But there will be nothing lazy about the events that will unfold as the merger proceeds. Gases will be compressed, and will keep compressing until they restructure to form new stars, bright and eager to start afresh. The black holes will embrace in a deadly tug of war, circling each other, taunting, each waiting for the other to succumb. The galaxies will give up some of their kinetic energy to the stars to tuck them safely in higher, wider orbits as far away from these black holes as possible that would otherwise engulf them mercilessly.
These invisible black holes will eventually merge in a violent collision and their final moments will shake the fabric of space time itself.
IGO/CALTECH/MIT/SONOMA STATE IMAGE. Violent Fusion of Black Holes. 2017. bbc.com. 17 Feb. 2018.
Soon, very soon, these giant profiles will disrupt each other to an extent that they’ll be unrecognizable for a long, long time. Billions of years later, when the things quieten, the only proof of the merger for those who look for it will be the giant elliptical galaxy.
Munching on this, I carry on, growing, expanding, accelerating.