According to Simulations, the Milky Way is One in a Million

As humans, we have a complex relationship with nature. Initially, we believed that we occupied the center of the universe. We also believed that the Sun and the entire cosmos revolved around the Earth, sustaining life. Yet, subsequent research has shown that Earth is not the center of the universe.

Centuries of study have demonstrated that our Sun is typical and our Solar System is relatively unremarkable. Nonetheless, our galaxy is just one of the billions of spiral galaxies in the universe, constituting 60% of all existence. While Earth and the life on it may be unique, the rest of the universe is vast and diverse.

The Illustris TNG Simulation Proves the Uniqueness of the Milky Way.

This simulation is an ongoing series of comprehensive projections to understand the mechanisms behind the galaxy’s evolution and its formation. Illustris TNG’s website describes this effort to understand the world as a “Series of Large, Cosmological Magnetohydrodynamical Simulations.”

By far, there have been three simulations of this project, each consisting of a higher resolution and performed on a larger scale than the previous one. All of these simulations focused on different aspects that contributed to forming the galaxy:

  1. The TNG 50
  2. The TNG 100
  3. The TNG 300

The TNG 300 has been the most significant simulation, simulating an area of approximately 300 million Megaparsecs. The TNG 300 goes over a billion light-years across and contains millions of galaxies.

The recent research on Illustric TNG points towards the uniqueness of the Milky Way. The research proves that the Milky Way is not unique for its intrinsic qualities but also due to its surroundings.

A research paper based on Illustris TNG 300 constitutes these findings. This research paper was written by a computational cosmologist, Miguel Aragon. Miguel is also an Assistant professor at the National Astronomical Observatory.

This research paper was published in “The Unusual Milky Way-local Sheet System: Implications for Spin Strength and Alignment,” a Monthly Notice of the Royal Astronomical Society.

The Illustris TNG is devoted to simulating the universe on a structure of a larger scale. The structure is designed to show galaxies’ arrangement on dark matter filaments. These filaments are spread out and pave their wave through the diverse cosmic voids.

One of the features they highlight is Galaxy walls, otherwise known as Cosmological walls. Made of Galaxies, The cosmological walls are a subtype of filaments. However, these walls are flattened and have voids on either side. The voids in them squash these Cosmological walls into a flattened shape.

It shouldn’t come off as a surprise to know that the largest known structure is a Cosmological wall named the Hercules–Corona Borealis Great Wall! This cosmological Wall is 10 billion light-years long.

Similarly, the Local Wall or Sheet is another Cosmological Wall closest to the Milky Way. This Wall influences The Milky Way’s rotation and nearby galaxies on their axis. A study proves that it takes approximately 250,000,000 years to rotate.

However, the rotation would be more organized if the galaxy was not located near the Local Wall. The study further proves the uniqueness of the Milky Way.

Whereas the standard galaxies share a much minimal relation with the Wall, the relation of the Milky Way is contradictorily more extensive. The study states that the significant relationship the Milky way shares with the Local Wall is a rare cosmic occurrence, vouching for its uniqueness.

To further prove the uniqueness of the Milky way, another factor comes into play: Velocity Dispersion. The Velocity Dispersion gives an idea of how much dispersal is present in the velocity of a grouped astronomical object. The velocities of the group object disperse around and give a mean velocity.

Concerning the Milky way, the velocity of objects in the Local Wall and Milky Way has low dispersion. The low dispersion between them indicates they have not dispersed away from the mean value.

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Credits: ESO

This condition is unusual for a high-mass galaxy like the Milky Way is close to the Local Wall. The researchers turned to Milky Way Analogues (MWA) galaxies in the Illustris TNG 300 to develop a better understanding of this condition.

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