Early galaxies grew massive through collisions - Woopdidoo?

Early galaxies grew massive through collisions

It has long puzzled scientists that there were enormously massive galaxies that were already old and no longer forming new stars in the very early universe, approx. 3 billion years after the Big Bang. Now new research from the Niels Bohr Institute, among others, shows that these massive galaxies were formed by explosive star formation that was set in motion by the collision of galaxies a few billion years after the Big Bang. The results are published in the scientific journal, Astrophysical Journal.

Source

I found this article after reading this thread, "Humans came long after aliens, scientist suggests", and pondering the old wrong aphorism, when you look up at a star, it's already dead.

Nore: Stars seen with the naked eye are far too close for that to be true, but the author of the above highlights that…

*I'll note that other galaxies are millions or even billions of light-years away, so the odds go up that many of the stars we see in them are already dead. But it takes a powerful telescope to see individual stars in a distant galaxy, so in my opinion this doesn't count either way toward the aphorism.

In any case, it made me think about all the long lost galaxies. What components besides water were around at the time (amino acids), and the futility of us ever really knowing what's inside them. Which somehow brought me to the topic article. Which I don't think has been posted yet.

This graphic compares the size of the extremely compact dead galaxies in the early universe, with the size of our own galaxy, the Milky way. The two galaxy types have approximately equal amounts of stars, which means that the density of stars in the compact galaxies is more that 10 times higher than in the Milky way. The researchers have now discovered how these extreme galaxies formed. (NASA, ESA, S. Toft og A. Feild)

Researchers were surprised to find galaxies as massive as todays elliptical and spiral galaxies back when the universe was in its infancy, 3 billions years old. (Like a cutesy wootsy universe baby).

These old giant baby galaxies, (reference), were much more tightly packed then todays giants. While the mass is similar, their stars were 10 times as dense and the overall galaxy size was 3 times smaller.

(See the above graphic with ex'd caption)

Another perplexing attribute was that these galaxies were dead as door knobs. With no new stars forming. Which left researchers scratching their heads.

Normal star formation (which is basically saying, "the explanation we have for star formation") didn't explain it. They decided to look back further in time, with the idea that smaller galaxies fusing together could cause this they found something to support this:

“We studied the galaxies that existed when the universe was between 1 and 2 billion years old. My theory that it must have been some galaxies with very specific properties that were part of the formation process made me focus on the special SMG galaxies, which are dominated by intense stare formation hidden under a thick blanket of dust,” explains Sune Toft.

He explains that when such gas-rich galaxies merge, all of the gas is driven into the centre of the system where it ignites an explosion of new star formation. A lot of stars are formed in the centre and the galaxy quickly becomes very compact. But with the explosive star formation, the gas to form new stars is also used up extremely quickly and then you get a dead galaxy.

“I discovered that there was a direct evolutionary link between two of the most extreme galaxy types we have in the universe – the most distant and most intense star forming galaxies which are formed shortly after the Big Bang – and the extremely compact dead galaxies we see 1-2 billion years later,” says Sune Toft. The new research is a breakthrough in discovering the formation process of the enormously massive and dead galaxies in the early universe.

www.nbi.ku.dk...

Which brings me back to the aphorism.

"For all those galaxies you are looking at through your multi-million dollar telescope near the beginning of time, they are most likely already dead, massive piles of dense (insert whatever they might be at this state)"

Sure it doesn't work for twitter, and it's not catchy, but it makes you think doesn't it?

reply to post by boncho

but it makes you think doesn't it?

It sure does.

I allways wondered what happens to a black hole(or grey as it might have become now), when it has sucked up all of the matter of a Galaxy, does it just float around doing nothing untill it meet some more matter, does it die, does explode starting everything over.

I don't think we have the answear to that yet or i can't find anything that answears that question, i know that two black holes can merge like two drops of water, but not what happens to a free floating black hole with no fuel.

Interesting

Mianeye
reply to post by boncho

 

but it makes you think doesn't it?

It sure does.

I allways wondered what happens to a black hole(or grey as it might have become now), when it has sucked up all of the matter of a Galaxy, does it just float around doing nothing untill it meet some more matter, does it die, does explode starting everything over.

If you don't eat you don't poo theory

reply to post by boncho

I always pictured galaxies forming the same way a spiral arms form when I turn on my sprinklers.

Supposedly, at the center of each galaxy resides a black hole. We have clearly seen plasma jets extending outwards from the center of some galaxies. What's to say a weakness doesn't form somewhere along it's spinning equator and spew forth enough matter to form everything else we see?

Ellipticals?? ... Somebody else'll have to figure those out.

reply to post by Mianeye


Just imagine these super dense galaxies form a super massive black hole that eventually blows up on the very inside, at the very center a new universe forms and the edges what used to be there are the edges of our universe.

Okay, okay, science fiction.

But I'm a big sci fi fan at heart.

-

Edit: Apparently not beyond the realm of valid inquisition however:

ur universe may exist inside a black hole. This may sound strange, but it could actually be the best explanation of how the universe began, and what we observe today. It's a theory that has been explored over the past few decades by a small group of physicists including myself.

Successful as it is, there are notable unsolved questions with the standard big bang theory, which suggests that the universe began as a seemingly impossible "singularity," an infinitely small point containing an infinitely high concentration of matter, expanding in size to what we observe today. The theory of inflation, a super-fast expansion of space proposed in recent decades, fills in many important details, such as why slight lumps in the concentration of matter in the early universe coalesced into large celestial bodies such as galaxies and clusters of galaxies.

But these theories leave major questions unresolved. For example: What started the big bang? What caused inflation to end? What is the source of the mysterious dark energy that is apparently causing the universe to speed up its expansion?

The idea that our universe is entirely contained within a black hole provides answers to these problems and many more. It eliminates the notion of physically impossible singularities in our universe. And it draws upon two central theories in physics.

www.insidescience.org...

Snarl
reply to post by boncho

 

I always pictured galaxies forming the same way a spiral arms form when I turn on my sprinklers.

Supposedly, at the center of each galaxy resides a black hole. We have clearly seen plasma jets extending outwards from the center of some galaxies. What's to say a weakness doesn't form somewhere along it's spinning equator and spew forth enough matter to form everything else we see?

Ellipticals?? ... Somebody else'll have to figure those out.

Ellipticals are thought to form when galaxies collide. The interesting thing about the ones they found is that they don't resemble either except the star movement is similar to an elliptical.

The extremely massive and compact galaxies were not flattened spiral galaxies where stars and gas rotate around the centre. Rather, they resembled elliptical galaxies where stars move more hither and thither and where the gas for new star formation has been used up. But how could the galaxies become so massive and so burnt out so early? How were they formed?

He explains that when such gas-rich galaxies merge, all of the gas is driven into the centre of the system where it ignites an explosion of new star formation. A lot of stars are formed in the centre and the galaxy quickly becomes very compact. But with the explosive star formation, the gas to form new stars is also used up extremely quickly and then you get a dead galaxy.

Instead of a sprinkler, think of someone cutting the hose.

boncho
reply to post by Mianeye

 

Just imagine these super dense galaxies form a super massive black hole that eventually blows up on the very inside, at the very center a new universe forms and the edges what used to be there are the edges of our universe.

Okay, okay, science fiction.

But I'm a big sci fi fan at heart.

Thats actually an awesome theory, a univers within a univers.

Good one

reply to post by Mianeye


Be sure to read this link, I found it just after posting and searching the idea.

Interesting read.

*The above post is edited with it too.

reply to post by boncho

That was very interesting, really thought provoking, it just went slightly beyond my intilligence barrier, so i might need to read it a couple of times(read, i will never be able to really understand it ).

I mean our own univers is "still expanding", so somehow it must get new matter from somewhere, but that maybe where Quasars and Blasars come in to the picture, so matter is constantly exchanced between universes and the black holes are the gateway between them....I don't know, just a thought. I know thats not how the article explaining it.


But cool find

reply to post by boncho

Interesting thread. It is a bit counterintuitive to some people that bigger stars have shorter lives, because in our everyday experience we tend to think "all that extra fuel, the larger star should last longer", but exactly the opposite happens, and of course stars can get pretty massive and burn up the fuel in a hurry when they do, so it's understandable how dead galaxies can happen afterwards.

Mianeye
I allways wondered what happens to a black hole(or grey as it might have become now), when it has sucked up all of the matter of a Galaxy, does it just float around doing nothing untill it meet some more matter, does it die, does explode starting everything over.

I don't think we have the answear to that yet or i can't find anything that answears that question

It depends on the age of the universe and the blackbody temperature of the cosmic microwave background radiation if the black hole Hawking radiation theory is correct. Part of the answer is in the Wiki on black holes:

In 1974, Hawking showed that black holes are not entirely black but emit small amounts of thermal radiation;[31] an effect that has become known as Hawking radiation. By applying quantum field theory to a static black hole background, he determined that a black hole should emit particles in a perfect black body spectrum. Since Hawking's publication, many others have verified the result through various approaches. If Hawking's theory of black hole radiation is correct, then black holes are expected to shrink and evaporate over time because they lose mass by the emission of photons and other particles. The temperature of this thermal spectrum (Hawking temperature) is proportional to the surface gravity of the black hole, which, for a Schwarzschild black hole, is inversely proportional to the mass. Hence, large black holes emit less radiation than small black holes.

A stellar black hole of one solar mass has a Hawking temperature of about 100 nanokelvins. This is far less than the 2.7 K temperature of the cosmic microwave background radiation. Stellar-mass or larger black holes receive more mass from the cosmic microwave background than they emit through Hawking radiation and thus will grow instead of shrink. To have a Hawking temperature larger than 2.7 K (and be able to evaporate), a black hole needs to have less mass than the Moon. Such a black hole would have a diameter of less than a tenth of a millimeter.

So that explains what we think will happen at this age in the universe, but over time, the 2.7 K temperature of the cosmic microwave background radiation will continue to decrease as it has been decreasing for billions of years already. As the CMB temperature decreases, then larger and larger black holes should be able to evaporate via hawking radiation.

But to my knowledge Hawking radiation has yet to be experimentally confirmed so this is a bit hypothetical (which is why the above has qualifiers like "If Hawking's theory of black hole radiation is correct...").