Scientists Discovered A New Way Galaxies Form

Scientists Discovered A New Way Galaxies Form


Do galaxies form because a bunch of baby stars
were all born at the same time, or are they hideous frankenstein monsters of galaxies
past? Hey space surfers, Julian here for DNews. You’d think we know everything there is
to know about galaxies by this point. I mean, we live in one, and when we look outside
of it, we think there are at least 2 trillion more. And that’s just in our slice of universe
that we can actually observe! So there’s no shortage of samples to study,
and yet we still have some very basic, very unanswered questions. Like, how do galaxies form? There’s no definitive model, but we thought
we had a pretty good idea until recent discovery has raised some eyebrows. Scientists studying a protogalaxy 10 billion
light years away known as the Spiderweb noticed that the large cloud of gas had young stars
popping up all across it. They were jumping to life out of the -200
celcius gas, which surprised the astronomers who were expecting something completely different. This discovery supports something called the
top-down approach of galaxy formation, which posits that the first galaxies started from
huge gas clouds that had enough internal gravity to collapse and begin star formation until
the clouds fragmented and became separate galaxies. The other bottom-up model is more widely accepted. It says stars formed in smaller clumps early
after the Big Bang. These clumps then mashed into and merged with
other clumps, getting bigger and bigger until they reached galactic proportions and settled
into orderly structures like the spiral and elliptical shapes we see in more recent galaxies
around us.This idea is supported by the fact that we observe a lot more small galaxies
than large ones, and when we look back we see clumpy looking galaxies and plenty of
mergers. In fact we think that nearly all massive galaxies
went through a merger at least once by the time the universe was 6 billion years old. So there’s evidence that supports both models. And of course, there are combinations of the
two models, and some even incorporate dark matter maps to help explain why the gas clumped
where it did. But these are just ideas, we need to look
back even farther to actually see what was going on in newborn galaxies. Right now the Hubble telescope’s infrared
instruments can look back to within hundreds of millions of years after the Big Bang, but
that’s not quite far enough. That’s part of why the James Webb Space
Telescope is such a big deal, it’ll allow us to look farther into the past than we ever
have before. Happily I will leave you with a mini mystery
that scientists think they’ve solved. The question of the roles supermassive black
holes play when a galaxy is first emerging from the cosmic soup was long the chicken-and-egg
dilemma of galaxy formation. We find these extremely dense points in space
at the center of most galaxies, and it’s thought that their gravity anchors the whole
thing. So do the galaxies condensing cause a black
hole to form, or does the black hole come first and help to pull the gas cloud together? For that pickle, it looks like it’s the
latter. While galaxies today appear to be proportional
to the mass of their central black holes, early galaxies have disproportionately large
black holes by comparison, suggesting the black holes come first. That answers that, but there are plenty more
mysteries out there, and maybe one day we’ll know just how our cosmic home came to be. So our galaxy has almost definitely been through
a merger before, and we’re going to do it again with our galactic neighbor, Andromeda. Now to brush up on it before it gets here,
check out Julia’s video right. So are you team top-down or a bottom-up kinda
guy or gal? Let us know in the comments, subscribe for
more and I’ll see you all next time on DNews