Scientists reveal most detailed simulation of the universe

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The most detailed model of the universe ever created has been unveiled by computer scientists. 

Dubbed ‘Illustris: The Next Generation’, or IllustrisTNG for short, the computer model boasts never-before-seen levels of details about the forces at work in the universe.

Scientists say the detail and scale provided by the advanced computer simulation has enabled them to observe how galaxies form, evolve, grow, and trigger the creation of new stars over 13 billion years.

They have already used it to provide new insights into how black holes influence the distribution of dark matter, how heavy elements are produced and distributed, and where magnetic fields originate. 

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Scientists believe shock waves may have helped create the infant cosmos. This visualisation in the Illustris shows the intensity of shock waves in the cosmic gas (blue) around collapsed dark matter structures (orange/white). Similar to a sonic boom, the gas in these shock waves is accelerated with a jolt when it hits cosmic filaments and galaxies

Dr Shy Genel, of the Flatiron Institute’s Centre for Computational Astrophysics, said: ‘When we observe galaxies using a telescope, we can only measure certain quantities.’

‘With the simulation, we can track all the properties for all these galaxies. And not just how the galaxy looks now, but its entire formation history’, Dr Genel added. 

To create this simulation, scientists used evidence of the earliest days of our universe, gathered from the cosmic microwave background leftover from the Big Bang.

This graphic shows a comparison of the distribution of intergalactic gas (mass), between the Illustris-1 (left) and TNG100-1 and (right) simulations. Low-density voids (black/dark blue) transition to cosmic filaments (yellow/green), gas halos (light blue) and individual galaxies (white)

Computational cosmologists use this data to model the conditions of the time, when the universe was just a few hundred thousand years old.

Into this virtual universe, they add baryonic matter, which forms stars and planets; dark matter, which enables galactic structures to grow; and dark energy, the mysterious force behind all cosmic acceleration.

These are coded into the simulation alongside equations that describe supernova explosions and black holes. 

Volker Springel, of the Heidelberg Institute for Theoretical Studies, was part of the international team that developed and programmed the simulation. 

Dr Springel said: ‘It is particularly fascinating that we can accurately predict the influence of supermassive black holes on the distribution of matter out to large scales.

Shown here is a thin slice through the cosmic large-scale structure in the largest simulation of the IllustrisTNG project. Brightness indicates mass density and colour indicates the gas temperature of ordinary matter. The displayed region extends by about 1.2 billion light-years from left to right. The underlying simulation is presently the largest magneto-hydrodynamic simulation of galaxy formation, containing more than 30 billion volume elements and particles

Shown here is a thin slice through the cosmic large-scale structure in the largest simulation of the IllustrisTNG project. Brightness indicates mass density and colour indicates the gas temperature of ordinary matter. The displayed region extends by about 1.2 billion light-years from left to right. The underlying simulation is presently the largest magneto-hydrodynamic simulation of galaxy formation, containing more than 30 billion volume elements and particles

‘This is crucial for reliably interpreting forthcoming cosmological measurements.’ 

Mark Vogelsberger, an assistant professor of physics at MIT and the MIT Kavli Institute for Astrophysics and Space Research, has been working to develop, test, and analyze the new IllustrisTNG simulations.

Vogelsberger used the IllustrisTNG model to show that the turbulent motions of hot, dilute gases drive small-scale magnetic dynamos that can exponentially amplify the magnetic fields in the cores of galaxies — and that the model accurately predicts the observed strength of these magnetic fields.

‘The high resolution of IllustrisTNG combined with its sophisticated galaxy formation model allowed us to explore these questions of magnetic fields in more detail than with any previous cosmological simulation,’ says Vogelsberger, an author on the three papers reporting the new work, published today in the Monthly Notices of the Royal Astronomical Society.  

HOW DO YOU CREATE A COMPUTER SIMULATION OF THE UNIVERSE? THE SCIENCE BEHIND ILLUSTRIS EXPLAINED

Scientists have created an entire universe inside a computer to learn about how our universe formed.

Dubbed Illustris: The Next Generation, or IllustrisTNG for short, the simulated cosmos is the most detailed ever created and has a diameter of one billion light-years.

To create this simulation, scientists used evidence of the earliest days of our universe, gathered from the cosmic microwave background leftover from the Big Bang.

Computational cosmologists use this data to model the conditions of the time, when the universe was just a few hundred thousand years old.

Into this virtual universe, they add baryonic matter, which forms stars and planets; dark matter, which enables galactic structures to grow; and dark energy, the mysterious force behind all cosmic acceleration.

These are coded into the simulation alongside equations that describe supernova explosions and black holes.

Cosmologists then watch and wait as the computer-powered simulation plays out what is believed to have happed 13.8 billion years ago – the virtual universe expands, gas condenses into small structures and eventually forms stars and galaxies.

Scientists said the detail and scale now provided by IllustrisTNG has enabled them to observe how galaxies form, evolve, grow, and trigger the creation of new stars.

This graphic shows the gas temperature (blue: cold, green: warm: white: hot), comparing original Illustris (left) to TNG100 (right) simulations. In both cases, the rapid temperature fluctuations and outbursts around nodes in the cosmic web are due to various energetic feedback processes, including energy from stars and high-velocity winds from supermassive black holes

The universe in the computer model is only one billion light-years across, compared to the observable universe, which has a diameter of about 93 billion light-years.

The previous model generated by the team four years ago measured 350 million light-years across.

Scientists have been able to follow the formation of millions of galaxies within the model of the universe – the largest simulation to explore how cosmic structures developed.

The model predicted a cosmic web of gas and dark matter which interacted to create galaxies which were similar to real galaxies in shape and size.

Dr Dylan Nelson, of the Max Planck Institute for Astrophysics, revealed how star-forming galaxies shine brightly in the blue light of their young stars until an evolutionary shift suddenly halts the star formation. 

Thin slice through the cosmic large-scale structure in the largest simulation of the IllustrisTNG project. Read more at: https://phys.org/news/2018-02-astrophysicists-illustristng-advanced-universe-kind.html#jCp Rendering of the gas velocity in a thin slice of 100-kiloparsec thickness (in the viewing direction), centered on the second most massive galaxy cluster in the TNG100 calculation. Where the image is black, the gas is hardly moving, while white regions have velocities which exceed 1,000 kilometers per second. The image contrasts the gas motions in cosmic filaments against the fast, chaotic motions triggered by the deep gravitational potential well and the supermassive black hole sitting at its center

Hot gas can be blasted out in streams of material ejected from hyperactive galaxies, as shown in this image from the computer simulation. Where the image is black, the gas is hardly moving, while white regions have velocities which exceed 1,000 kilometers per second. The image contrasts the gas motions in cosmic filaments against the fast, chaotic motions triggered by the deep gravitational potential well and the supermassive black hole sitting at its center

This turns the galaxy into one dominated by old, rest stars.

Dr Nelson explained: ‘The only physical entity capable of extinguishing the star formation in our large elliptical galaxies are the supermassive black holes at their centres.

‘The ultrafast outflows of these gravity traps reach velocities up to 10 per cent of the speed of light and affect giant stellar systems that are billions of times larger than the comparably small black hole itself.’

In addition, the simulations were able to predict how the cosmic web changes over time, especially in relation to dark matter, which purportedly makes up 26.8 per cent of the universe.

By contrast, ordinary matter makes up just 4.9 per cent of the observable universe. The remaining 68.3 per cent of the observable universe is believed to be dark energy.

Annalisa Pillepich, a researcher at Max-Planck Institute for Astronomy, said: ‘Our predictions can now be systematically checked by observers.

‘This yields a critical test for the theoretical model of hierarchical galaxy formation.’ 

Each view shows a different output of the simulation (from left to right, top): gas matter density, dark matter density, stellar mass, magnetic field strength, (bottom) gas temperature, gas metallicity, the velocity field of the gas, and column density of OVI – the fifth ionization state of oxygen 

This illustration shows interstellar magnetic field strength, with blue/purple indicating regions of low magnetic energy arranged along filaments of the cosmic web, while orange and white show regions with significant magnetic energy inside halos and galaxies

This illustration shows interstellar magnetic field strength, with blue/purple indicating regions of low magnetic energy arranged along filaments of the cosmic web, while orange and white show regions with significant magnetic energy inside halos and galaxies

Fixed in time, the video slowly rotates in space to show the structure from different view points of the most massive cluster of TNG300. Each of the four panels shows the same predicted X-ray emission (in background colour), while the overlaid contours show predicted synchrotron emissions, as would be observed by one of four radio telescopes 





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