Chapter 1: The TNG50 Simulation

Recent advancements in astronomical simulations have enabled scientists to explore the formation and evolution of countless galaxies with exceptional precision. The TNG50 simulation, the most comprehensive of its kind, has provided insights into the cosmos over an impressive span of 13.8 billion years.

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Section 1.1: Insights into Cosmic Evolution

The TNG50 simulation, developed by researchers from the US and Germany, allows for a detailed examination of how galaxies have formed and evolved since the early moments post-Big Bang. The findings, detailed in two studies published in the Monthly Notices of the Royal Astronomical Society, indicate that the structure of cosmic gas flows around nascent galaxies significantly influenced their formation.

The first results from this groundbreaking simulation were shared by a team led by Dr. Annalisa Pillepich and Dr. Dylan Nelson from the Max Planck Institute. They discovered several unexpected physical phenomena. “Numerical experiments of this kind yield more insights than anticipated. Our simulation unveiled behaviors not explicitly coded,” Nelson explained.

This video titled "Building A Universe In A Box | Dr Christopher Lovell & Will Roper" delves into how simulations like TNG50 are reshaping our understanding of cosmic evolution.

Section 1.2: Emergent Behaviors in Galaxies

The TNG50 simulation serves as a sort of time machine, allowing researchers to rewind the development of cosmic structures. It reveals the transition from chaotic gas clouds to well-ordered, rapidly spinning disc galaxies, such as our Milky Way. As gas settles, new stars form on increasingly circular paths, eventually leading to the emergence of spiral galaxies.

Pillepich noted, “TNG50 illustrates that our Milky Way, with its thin disc, represents a peak in galactic evolution. Over the last 10 billion years, star-forming galaxies have increasingly adopted disc-like structures, with their internal chaos significantly diminishing. The universe was far more chaotic in its infancy!”

Chapter 2: Cosmic Fountains and Galactic Dynamics

The second key emergent property identified in TNG50 involves galaxies flattening out due to high-speed outflows driven by supermassive black holes and stellar explosions. Initially, these outflows are chaotic, but over time they align along the path of least resistance, forming two cones extending along the galaxies' rotational axes.

This video titled "GALAXIES - 3 Hours of Scientific Space Discoveries Part 2/2" provides an extensive overview of galactic phenomena, including the dynamics of gas flow in galaxies.

These outflows can slow down when encountering gravitational wells created by dark matter halos, often resulting in gas stalling and re-accreting into the galaxy, resembling a cosmic fountain that redistributes gas from the galaxy's center to its outskirts, promoting the formation of a thinner disc.

The TNG50 simulation successfully merges the detail of small-scale studies with the expansive nature of large-scale simulations, achieving a unique perspective on the evolution of the cosmos. It encompasses a virtual universe over 230 million light-years across, allowing scientists to trace the intricate histories of thousands of galaxies through the use of 20 billion particles representing various cosmic components.

The computational effort required for TNG50 was immense, utilizing 16,000 cores on the Hazel Hen supercomputer, equivalent to 15,000 years of processing on a single unit. The results promise to be just the beginning, with the research team planning to share all simulation data for the astronomy community and the public, opening avenues for further discoveries in this simulated universe.