Researchers reveal the story of the oldest stars and galaxies, compiled from 20 years of simulating the early universe

black hole
This computer-simulated image shows a supermassive black hole at the core of a galaxy. The black region in the center represents the black hole's event horizon, where no light can escape the massive object's gravitational grip. The black hole's powerful gravity distorts space around it like a funhouse mirror. Light from background stars is stretched and smeared as the stars skim by the black hole. Credit: NASA, ESA, and D. Coe, J. Anderson, and R. van der Marel (STScI)

The Big Bang has captured our imagination like no other theory in science: the magnificent, explosive birth of our Universe. But do you know what came next?

Around 100 million years of darkness.

When the cosmos eventually lit up its very first stars, they were bigger and brighter than any that have followed. They shone with UV light so intense, it turned the surrounding atoms into ions. The Cosmic Dawn—from the first star to the completion of this 'cosmic reionization', lasted roughly one billion years.

"Where did these stars come from? And how did they become the galaxies—the Universe teeming with radiation and plasma—that we see today? These are our driving questions," says Professor Michael Norman, Director of the San Diego Supercomputer Center and lead author of a new review published in Frontiers in Astronomy and Space Sciences.

The Universe in a Box

Researchers like Professor Norman solve mathematical equations in a cubic .

"We have spent over 20 years using and refining this software, to better understand the Cosmic Dawn."

To start, code was created which allowed formation of the first stars in the to be modeled. These equations describe the movement and chemical reactions inside gas clouds in a universe before light, and the immense of a much larger but invisible mass of mysterious .

"These clouds of pure hydrogen and helium collapsed under gravity to ignite single, massive stars—hundreds of times heavier than our Sun," explains Norman.

The very first heavy elements formed in the pressure-cooker cores of the first stars: just a smidgen of lithium and beryllium. But with the death of these short-lived giants—collapsing and exploding into dazzling supernovae—metals as heavy as iron were created in abundance and sprayed into space.

Equations were added to the virtual Universe to model enrichment of gas clouds with these newly formed metals—which drove formation of a new type of star.

"The transition was rapid: within 30 million years, virtually all new stars were metal-enriched."

This is despite the fact that chemical enrichment was local and slow, leaving more than 80% of the virtual Universe metal-free by the end of the simulation.

"Formation of metal-free giant stars did not stop entirely—small galaxies of these stars should exist where there is enough dark matter to cool pristine clouds of hydrogen and helium.

"But without this huge gravitational pull, the intense radiation from existing stars heats gas clouds and tears apart their molecules. So in most cases, the metal-free gas collapses entirely to form a single, supermassive black hole."

From stars to galaxies

"The new generations of stars that formed in galaxies are smaller and far more numerous, because of the chemical reactions made possible with metals," Norman observes.

The increased number of reactions in allowed them to fragment and form multiple stars via 'metal line cooling': tracts of decreased gas density, where combining elements gain room to radiate their energy into space—instead of each other.

At this stage we have the first objects in the universe that can rightfully be called galaxies: a combination of dark matter, metal-enriched gas, and stars.

"The first galaxies are smaller than expected because intense radiation from young, massive stars drives dense gas away from star-forming regions.

"In turn, radiation from the very smallest galaxies contributed significantly to cosmic reionization."

These hard-to-detect but numerous can therefore account for the predicted end date of the Cosmic Dawn—i.e., when cosmic reionization was complete.

Thinking outside the box

Norman and colleagues explain how some groups are overcoming computing limitations in these numerical simulations by importing their ready-made results, or by simplifying parts of a model less relevant to the outcomes of interest.

"These semi-analytical methods have been used to more accurately determine how long massive metal-free early stars were being created, how many should still be observable, and the contribution of these—as well as black holes and metal-enriched —to cosmic reionization."

The authors also highlight areas of uncertainty that will drive a new generation of simulations, using new codes, on future high-performance computing platforms.

"These will help us to understand the role of magnetic fields, X-rays and space dust in gas cooling, and the identity and behavior of the mysterious dark matter that drives star formation."


Explore further

Astronomers identify some of the oldest galaxies in the universe

More information: Frontiers in Astronomy and Space Sciences, DOI: 10.3389/fspas.2018.00034 , https://www.frontiersin.org/articles/10.3389/fspas.2018.00034/full
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Citation: Researchers reveal the story of the oldest stars and galaxies, compiled from 20 years of simulating the early universe (2018, October 17) retrieved 21 May 2019 from https://phys.org/news/2018-10-reveal-story-oldest-stars-galaxies.html
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Oct 17, 2018
To start, code was created which allowed formation of the first stars in the universe to be modeled. These equations describe the movement and chemical reactions inside gas clouds in a universe before light, and the immense gravitational pull of a much larger but invisible mass of mysterious dark matter.

This model is TOTALLY dependent on the existence and supposed FUTURE discovery and "observation" of dark matter. To put it bluntly, it is currently based on false assumptions.

We know for a fact that a cloud of H and He gas cannot collapse all by itself under self-gravity and ignite a fusion reaction. The Jeans Mass limitation prevents that event from occurring. As does the magnetic fields that pervades the cloud as it tries to condense.

So, to overcome those problems enter the dark matter to magically solve the issue at hand.

This is pure magic. It would be great if the researchers stated up front that the magic cannot happen unless dark matter is invoked.
FAIL.

Oct 17, 2018
At this stage we have the first objects in the universe that can rightfully be called galaxies: a combination of dark matter, metal-enriched gas, and stars.


Dark matter once again. Magic. Of. The. First. Kind.

Oct 17, 2018
Dark Matter = Stupid Geniuses

Oct 17, 2018
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

Displaced supersolid dark matter is curved spacetime.

Oct 17, 2018
Just look at the PseudoScienceCrowd above. They are getting more and more vocal, louder and louder.
Remember how the same thing happened some years ago when AGW was still slightly in dispute?
As the deniers position became more and more untenable they did the same thing. Desperation makes them panicky.
Pretty soon we will have the rest of them here as well, getting even more vocal. They make up in quantity what they lack in quality.

Oct 18, 2018
And not a single one of the cult dolts can produce a working device based upon their whacky-happy faked science.

Except for what they steal from real scientists and try to claim as their own work.

Oct 19, 2018
"The Big Bang has captured our imagination like no other theory in science: the magnificent, explosive birth of our Universe. But do you know what came next?"

You should rather ask what happened BRFORE as the Big Bounce is a more natural explanation of birth/evolution of anything than some magnificent explosion from nothing. What about turning the increased (but balanced) motion and gravitational energy of total mass M in contracting 3-D space of Riemann closed 4-sphere energy system into the expansion phase of decreasing (but balanced) motion and gravitational energies at Big Bounce vs. Big Bang? The inflationary expansion of GRT/QM based BB assumption then becomes deflationary revealing the true story of oldest stars near T4=0 where C and the expansion speed C4=C of 4-radius were much larger than today because of the high ticking rate of dynamic atomic processes. It prompted galaxy/star formation from the seed of the contraction phase and previous bouncing eras.

Oct 20, 2018
annoyingmousie, creeping backwards with your pointy-little head firmly implanted within your ass.
"...You should rather ask what happened BRFORE..."

"And the envelope, Please!"

The most common scientific explanation is nothing, nothing at all. TAH-DAH! The common scientific explanation is there is simply no way to ever conclusively know.

My old theory is that there was nothing but gravitrons roiling in cthonic chaos. That at a random interval of No-Time, accidentally broke. Whoops!

Producing the phenomena called the Big Bang and mistakenly resulting in the Universe we love to gape at.

The Universe, bobbing along in the gravitrons surrounding it, is being pulled apart from the outside. Which explains why the expansion continues ro accelerate. Not Dark Energy pushing the Universe outward.

My newer theory takes advantage of the newly discovered (Not yet confirmed!) Majoron particle. (Obsolete term - Dark Matter) I guess producing Majorarcana as Dark Energy?

Nov 18, 2018
Cool, LCDM advances here too.

So, no need to respond to the crackpots who are, as noted, reduced to yell their protests.

But this can be responded to:

You should rather ask what happened BRFORE as the Big Bounce is a more natural explanation of birth/evolution of anything than some magnificent explosion from nothing.


No and no - bounce theories are problematic for obvious reasons (such as what about the ever increasing entropy) and LCDM claim neither "explosion" nor "nothing".

LCDM incorporates the observed expansion of the universe, but that is not an explosion - it happened everywhere at a moment in time and the universe is too uniform to be "exploding" (or bouncing for that matter). That is why inflation was discovered.

The observed type of inflation is slow roll, far from Planck energies and naturally eternal (creating local initially hot matter filled universes such as ours). "Nothing" is a religious idea. we see space and time looking back.

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