New Simulation Recreates an Early Time in the Universe That Still Hasn't Been Seen Directly

The fields of astronomy and astrophysics are poised for a revolution. Scientists will finally be able to see the formation of the first stars and galaxies in the Universe thanks to the next generation of telescopes. They will be able to pierce the veil of the Cosmic Dark Ages, which lasted from 370,000 years to 1 billion years after the Big bang.

Clouds of neutral hydrogen and decoupled photons were not visible to the astronomer. A new simulation suite called Thesan was created by researchers from the Harvard & Smithsonian Center for Astrophysics, the Massachusetts Institute of Technology, and the Max Planck Institute for Astrophysics.

Three papers about the Thesan suite and the results obtained by the team were recently accepted to the Monthly Notices of the Royal Astronomical Society. The simulations were created using the SuperMUC-NG supercomputer. The process took over 30 million hours to complete and would have taken over 3,500 years to complete on a conventional computer.

The simulations cover the history of reionization. 13 billion years ago. Light was able to spread throughout the Universe because neutral hydrogen atoms were ionized to form positive hydrogen atoms. It was no easy task to recreate the chaotic interactions between gravity, gas, radiation, and more. It took physics down to a million times smaller than the simulations.

The team accomplished this by combining realistic models of galaxy formation and cosmic dust with a new algorithm that tracks how light interacts with gas. They were able to resolve interactions in the early Universe in unprecedented detail and over the largest volume of any previous simulation. The lead author of the first paper in the series is an astronomer at the CfA.

“Most astronomers don’t have labs to conduct experiments in. The scales of space and time are too large, so the only way we can do experiments is on computers. We are able to take basic physics equations and governing theoretical models to simulate what happened in the early universe.”

“A lot of telescopes coming online, like the JWST, are specifically designed to study this epoch. That’s where our simulations come in; they are going to help us interpret real observations of this period and understand what we’re seeing.”

Researchers can use the new simulation suite to model a piece of our Universe. The formation of the first galaxies in this space can be tracked and visualized by running it forward in time. The team found that the transition from darkness to light was gradual.

The study co-author is a NASA Einstein Fellow in MIT.

When you put it in the freezer, it takes time, but after a while it starts to freeze on the edges and slowly creeps in. In the early Universe, it was a neutral, dark place that became bright and ionized as light began to emerge from the first galaxies.

The simulations were created to prepare for the next generation of telescopes. Along with ground-based telescopes, these observatories will be able to see deeper into space and back in time than their predecessors. It is thought that James will be able to see the Universe the same way it was 13 billion years ago.

Earendel, a star located about 12.9 billion light-years from Earth, is currently the most distant single object ever seen. The record goes to GN-z11, which is located in the constellation Ursa Major. It is exciting that the community won't have to wait long for real telescope observations and data to be compared to Thesan simulations.

The Thesan simulations and model will agree with what the JWST finds.

The team won't know how their model stacks up against the real thing until the first observations are available. They will try to match various aspects of their model to the observations, including the properties of early galaxies and the absorption and escape of light in the early Universe. The Dark Ages were dispelled from this.

Kannan says that they have developed simulations based on what they know.

Astronomers have been waiting for the day when it would be possible to view the earliest periods of the Universe. Scientists will finally be able to address some of the deepest mysteries of the universe with the help of observations of how the cosmos has evolved. It is exciting to know that such a day is around the corner.

Thesan simulation has a 3D view. There are more simulations on their page.

There is a Harvard-Smithsonian Center for Astrophysics.