Simulation Gives a Peek Into The Cosmic 'Dark Age' of Star Formation

 For astronomers, astrophysicists, and cosmologists, the power to identify the primary stars that formed in our Universe has always been just beyond reach. On the one hand, there are the bounds of our current telescopes and observatories, which might only see thus far.

The farthest object ever observed was MACS 1149-JD, a galaxy located 13.2 billion light-years from Earth that was spotted within the Hubble eXtreme Deep Field (XDF) image.

On the opposite, up until about 1 billion years after the large Bang, the Universe was experiencing what cosmologists check with because the "Dark Ages" when the Universe was stuffed with gas clouds that obscured visible and infrared radiation.

Luckily, a team of researchers from Georgia Tech's Center for Relativistic Astrophysics recently conducted simulations that show what the formation of the primary stars appeared like.

The study that describes their findings, published within the Monthly Notices of the Royal Astronomical Society, was led by Gen Chiaki and John Wise – a post-doctoral researcher and professor from the CfRA (respectively).

They were joined by researchers from the Sapienza Università di Roma, the Astronomical Observatory of Rome, the Istituto Nazionale di Astrofisica (INAF), and also the Istituto Nazionale di Fisica Nucleare (INFN).

Based on the life and death cycles of stars, astrophysicists theorize that the primary stars within the Universe were very metal-poor. Having formed about 100 million years after the large bang, these stars formed from a primordial soup of hydrogen gas, helium, and trace amounts of sunshine metals.

These gases would collapse to make stars that were up to 1,000 times more massive than our Sun.

Because of their size, these stars were short-lived and possibly only existed for some million years. in this time, the new and heavier elements in their nuclear furnaces, which were then dispersed once the celebrities collapsed and exploded in supernovae.

As a result, the subsequent generation of stars with heavier elements would contain carbon, resulting in the designation of Carbon-Enhanced Metal-Poor (CEMP) stars.

The composition of those stars, which can be visible to astronomers today, is that the results of the nucleosynthesis (fusion) of heavier elements from the primary generation of stars.

By studying the mechanism behind the formation of those metal-poor stars, scientists can infer what was happening during the cosmic 'Dark Ages' when the primary stars formed. As Wise said in an exceedingly Texas Advanced Computer Center (TACC) press release:

"We can't see the very first generations of stars. Therefore, it is important to really study these living fossils from the first universe, because they need the fingerprints of the primary stars everywhere them through the chemicals that were produced within the supernova from the primary stars."

"That's where our simulations get to play to determine this happening. After you run the simulation, you'll watch a brief movie of it to determine where the metals come from and the way the primary stars and their supernovae actually affect these fossils that live until this day."

Density, temperature, and carbon abundance (top) and the formation cycle of Pop III stars (bottom). (Chiaki, et al.)

For the sake of their simulations, the team relied predominantly on the Georgia Tech PACE cluster. extra time was allocated by the National Science Foundation's (NSF) Extreme Science and Engineering Discovery Environment (XSEDE), the Stampede2 supercomputer at TACC and NSF-funded Frontera system (the fastest academic supercomputer within the world), and also the Comet cluster at the urban center Supercomputer Center (SDSC).

With the huge amounts of processing power and data storage these clusters provided, the team was ready to model the faint supernova of the primary stars within the Universe.

What this revealed was that the metal-poor stars that formed after the primary stars within the Universe became carbon-enhanced through the blending and fallback of bits ejected from the primary supernovae.

Their simulations also showed the gas clouds produced by the primary supernovae were seeding with carbonaceous grains, resulting in the formation of low-mass 'giga-metal-poor' stars that likely still exist today (and may well be studied by future surveys). Said Chiaki of those stars:

"We find that these stars have very low iron content compared to the observed carbon-enhanced stars with billionths of the solar abundance of iron. However, we are able to see the fragmentation of the clouds of gas. this means that the Mass stars form during a low iron abundance regime. Such stars haven't been observed yet. Our study gives us theoretical insight into the formation of first stars."

A new study looked at 52 submillimeter galaxies to help us understand the early ages of our Universe. (University of Nottingham/Omar Almaini)

These investigations are a part of a growing field referred to as "galactic archaeology."

Much like how archaeologists depend upon fossilized remains and artifacts to find out more about societies that disappeared centuries or millennia ago, astronomers rummage around for ancient stars to review so as to find out more about those who have lang syne died.

According to Chiaki, the following step is to vary beyond the carbon features of ancient stars and incorporate other heavier elements into larger simulations. In so doing, galactic archaeologists hope to be told more about the origins and distribution of life in our Universe. Said Chiaki:

"The aim of this study is to grasp the origin of elements, like carbon, oxygen, and calcium. These elements are concentrated through the repetitive matter cycles between the interstellar space and stars. Our bodies and our planet are made from carbon and oxygen, nitrogen, and calcium. Our study is incredibly important to assist understand the origin of those elements that we mortals are fabricated from."