Spotted: Gas Clouds From the Early Universe, Older Than Metals Themselves

Huge primordial gas clouds made of elements untouched since moments after the big bang have been discovered by a group of scientists, offering a glimpse into what the universe looked like in its infancy.

The clouds aren?t the oldest celestial objects astronomers can see?they?re from about two billion years after the big bang, and astronomers have spotted parts of the universe that date to less than one billion years after the event. But they are the first glimpse of a universe without most of the elements surrounding us today.

According to the big bang model, only the first two elements on the periodic table, hydrogen and helium, existed in the very early universe. All the heavier elements came around when the first stars began exploding in supernovae and dispersing the heavy metallic elements they had created through fusion, says John O?Meara, a professor at Saint Michael?s College in Vermont who was an author on the new study. "When a massive star runs out of its fuel it explodes in a supernovae," he says. "The explosions are so violent that it kicks this stuff [heavy elements] out of the galaxy."

In their study appearing this week in Science, O?Meara and his fellow researchers discovered two clouds that, while being distant from each other, share the distinction as the first places that scientists have been able to find zero traces of metallic elements, and thus peek into the early universe.

Astronomers cannot actually see these distant clouds directly. Instead, they have used the light from quasars?extremely luminous star-like objects that form after the collapse of a black hole?as a medium to analyze the clouds in.

The quasar?s light has traveled through a lot of material on its way to earth before astronomers finally see it, and astronomers can take a spectrum of the quasar light to see that elements it has traveled through. It?s a little like looking at the light?s passport, the researchers explain, which each gas leaving its stamp. And according to UC Santa Cruz doctoral student Michele Fumagalli, who helped on the study, the team can control for any gases that the light travels through that aren?t a part of the studied primordial cloud.

"We know where we expect to see the lines of the gases we want to study, so we just look at those positions and we don?t look at other regions that we are not interested in," he says. And when they did, they found that the ancient gas clouds showed no metallic traces whatsoever.

A Confirmation and a Question

The team?s finding backs up what scientists thought about the big bang, but at the same time, it brings up some interesting questions.

Researchers have been analyzing quasar light for decades, but it wasn?t until scientists grabbed a few spectrums taken five years ago and reanalyzed them by hand in June that they realized they had new evidence to back up the big bang theory. "This is very good news because the existence of gas without metal has been predicted by the big bang theory but never observed," Fumagalli says. "So the fact that we are seeing these gases there is now empirical evidence that this theory is correct."

It certainly surprised Christopher Howk, a physics professor at the University of Notre Dame, who wasn?t involved in the study. "I actually was kind of shocked that they found this, because I had kind of given up hope that they would find this anytime soon, especially the way they did."

However, while these findings are more validation for the big bang theory, the researchers say that the existence of these pure clouds means they might have to rethink how the universe recycles material. The material in the pure clouds was made minutes after the big bang, but surprisingly, avoided pollution for roughly two billion years. The location of these finds wasn?t what Howk expected, either. "What I expected was, you might be able to find some material that was extremely devoid of metals in regions that we know are well-away from galaxies, in the most vacuous parts of space," he says.?"What they?ve actually found is [in an area of] pretty high density, and usually that means that you are in the near environment of a galaxy. [Yet] they find this thing sitting out there seemingly uncontaminated."

To O?Meara, it means there are some key questions astronomers still must answer: "Up until now we have always seen heavy elements around galaxies, so we have made the assumption that galaxies are very good at spreading heavy elements around. It calls into question what?s going on, on the very largest scales about spreading heavy elements around. If there are a large portion of [unpolluted areas] out there and we just haven?t been finding them, then that means we might have gotten something drastically wrong."

The universe?s recycling of materials is necessary to understanding the life cycle of celestial bodies, including our own galaxy. "There are some galaxies out there in the universe that are the same age as our own, which are no longer making stars. And there?s a complicated set of reasons for why this is," O?Meara says. "But we need to be able to understand all the sources and sinks of gases that can be made into stars.

Plus, Fumagalli says, understanding the movement of elements around the universe helps researchers across astronomy. "It is also of interest to people who study stars in our own galaxy," he says. "They can have a very accurate measure of the chemical composition of the stars in the Milky Way."

Source: http://www.popularmechanics.com/science/space/deep/spotted-gas-clouds-from-the-early-universe-older-than-metals-themselves-6554368?src=rss

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