Illustris project

The Illustris project is an ongoing series of astrophysical simulations run by an international collaboration of scientists.[1] The aim is to study the processes of galaxy formation and evolution in the universe with a comprehensive physical model. Early results are described in a number of publications[2][3][4] following widespread press coverage.[5][6][7] The project publicly released all data produced by the simulations in April, 2015. A followup to the project, IllustrisTNG, was presented in 2017.

Illustris Simulation

Overview

The original Illustris project was carried out by Mark Vogelsberger[8] and collaborators as the first large-scale galaxy formation application of Volker Springel's novel Arepo code.[9][9]

The Illustris project includes large-scale cosmological simulations of the evolution of the universe, spanning initial conditions of the Big Bang, to the present day, 13.8 billion years later. Modeling, based on the most precise data and calculations currently available, are compared to actual findings of the observable universe in order to better understand the nature of the universe, including galaxy formation, dark matter and dark energy.[5][6][7]

The simulation includes many physical processes which are thought to be critical for galaxy formation. These include the formation of stars and the subsequent "feedback" due to supernova explosions, as well as the formation of super-massive black holes, their consumption of nearby gas, and their multiple modes of energetic feedback.[1][4][10]

Images, videos, and other data visualizations for public distribution are available at official media page.

Computational aspects

The main Illustris simulation was run on the Curie supercomputer at CEA (France) and the SuperMUC supercomputer at the Leibniz Computing Center (Germany).[1][11] A total of 19 million CPU hours was required, using 8,192 CPU cores.[1] The peak memory usage was approximately 25 TB of RAM.[1] A total of 136 snapshots were saved over the course of the simulation, totaling over 230 TB cumulative data volume.[2]

A code called "Arepo" was used to run the Illustris simulations. It was written by Volker Springel, the same author as the GADGET code. The name is derived from the Sator Square. This code solves the coupled equations of gravity and hydrodynamics using a discretization of space based on a moving Voronoi tessellation. It is optimized for running on large, distributed memory supercomputers using a MPI approach.

Public data release

In April, 2015 (eleven months after the first papers were published) the project team publicly released all data products from all simulations.[12] All original data files can be directly downloaded through the data release webpage. This includes group catalogs of individual halos and subhalos, merger trees tracking these objects through time, full snapshot particle data at 135 distinct time points, and various supplementary data catalogs. In addition to direct data download, a web-based API allows for many common search and data extraction tasks to be completed without needing access to the full data sets.

German Postal Stamp

In December 2018, the Illustris simulation was recognized by the Deutsche Post through a special series stamp.

IllustrisTNG

Overview

The IllustrisTNG project, "the next generation" follow up to the original Illustris simulation, was first presented in July, 2017. The project was achieved by a team of scientists from Germany and the U.S. led by Prof. Volker Springel.[13] First, a new physical model was developed, which among other features now includes Magnetohydrodynamics. Three simulations are planned, which are different volumes at different resolutions. The intermediate simulation (TNG100) is equivalent to the original Illustris simulation.

Unlike Illustris, it was run on the Hazel Hen machine at the High Performance Computing Center, Stuttgart in Germany. Up to 25.000 computer cores were employed.

Public data release

In December 2018 the simulation data from IllustrisTNG was released publicly. The data service includes a JupyterLab interface.

Gallery

Stamp illustris

Stamp of German Postal Service in honor of the Illustris Simulation (2018)

Illustris Galaxien

Galaxies predicted by the Illustris Simulation

Tnggas

Large-scale Gas Distribution of IllustrisTNG: the Illustris follow-up simulation

Illustristng

IllustrisTNG: the Illustris follow-up simulation

See also

References

  1. ^ a b c d e Staff (14 June 2014). "The Illustris Simulation - Towards a predictive theory of galaxy formation". Retrieved 16 July 2014.
  2. ^ a b Vogelsberger, Mark; Genel, Shy; Springel, Volker; Torrey, Paul; Sijacki, Debora; Xu, Dandan; Snyder, Greg; Nelson, Dylan; Hernquist, Lars (14 May 2014). "Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe" (PDF). Monthly Notices of the Royal Astronomical Society. 444 (2): 1518–1547. arXiv:1405.2921. Bibcode:2014MNRAS.444.1518V. doi:10.1093/mnras/stu1536.
  3. ^ Genel, Shy; Vogelsberger, Mark; Springel, Volker; Sijacki, Debora; Nelson, Dylan; Snyder, Greg; Rodriguez-Gomez, Vicente; Torrey, Paul; Hernquist, Lars (15 May 2014). "The Illustris Simulation: the evolution of galaxy populations across cosmic time" (PDF). Monthly Notices of the Royal Astronomical Society. 445 (1): 175–200. arXiv:1405.3749. Bibcode:2014MNRAS.445..175G. doi:10.1093/mnras/stu1654.
  4. ^ a b Vogelsberger, M.; Genel, S.; Springel, V.; Torrey, P.; Sijacki, D.; Xu, D.; Snyder, G.; Bird, S.; Nelson, D.; Hernquist, L. (8 May 2014). "Properties of galaxies reproduced by a hydrodynamic simulation". Nature. 509 (7499): 177–182. arXiv:1405.1418. Bibcode:2014Natur.509..177V. doi:10.1038/nature13316. PMID 24805343.
  5. ^ a b Aguilar, David A.; Pulliam, Christine (7 May 2014). "Astronomers Create First Realistic Virtual Universe - Release No.: 2014-10". Harvard-Smithsonian Center for Astrophysics. Retrieved 16 July 2014.
  6. ^ a b Overbye, Dennis (16 July 2014). "Stalking the Shadow Universe". The New York Times. Retrieved 16 July 2014.
  7. ^ a b Nemiroff, R.; Bonnell, J., eds. (12 May 2014). "Illustris Simulation of the Universe". Astronomy Picture of the Day. NASA. Retrieved 16 July 2014.
  8. ^ "MIT Department of Physics". web.mit.edu. Retrieved 2018-11-22.
  9. ^ a b Vogelsberger, Mark; Sijacki, Debora; Kereš, Dušan; Springel, Volker; Hernquist, Lars (2012-09-05). "Moving mesh cosmology: numerical techniques and global statistics". Monthly Notices of the Royal Astronomical Society. 425 (4): 3024–3057. arXiv:1109.1281. Bibcode:2012MNRAS.425.3024V. doi:10.1111/j.1365-2966.2012.21590.x. ISSN 0035-8711.
  10. ^ Vogelsberger, Mark; Genel, Shy; Sijacki, Debora; Torrey, Paul; Springel, Volker; Hernquist, Lars (2013-10-23). "A model for cosmological simulations of galaxy formation physics". Monthly Notices of the Royal Astronomical Society. 436 (4): 3031–3067. arXiv:1305.2913. Bibcode:2013MNRAS.436.3031V. doi:10.1093/mnras/stt1789. ISSN 1365-2966.
  11. ^ Mann, Adam (7 May 2014). "Supercomputers Simulate the Universe in Unprecedented Detail". Wired. Retrieved 18 July 2014.
  12. ^ Nelson, D.; Pillepich, A.; Genel, S.; Vogelsberger, M.; Springel, V.; Torrey, P.; Rodriguez-Gomez, V.; Sijacki, D.; Snyder, G. F.; Griffen, B.; Marinacci, F.; Blecha, L.; Sales, L.; Xu, D.; Hernquist, L. (14 May 2014). "The Illustris Simulation: Public Data Release". Astronomy and Computing. 13: 12–37. arXiv:1504.00362. Bibcode:2015A&C....13...12N. doi:10.1016/j.ascom.2015.09.003.
  13. ^ "Mitarbeiter | Max-Planck-Institut für Astrophysik". www.mpa-garching.mpg.de. Retrieved 2018-11-22.

External links

Age of the universe

In physical cosmology, the age of the universe is the time elapsed since the Big Bang. The current measurement of the age of the universe is 13.799±0.021 billion (109) years within the Lambda-CDM concordance model. The uncertainty has been narrowed down to 21 million years, based on a number of projects that all give extremely close figures for the age. These include studies of the microwave background radiation, and measurements by the Planck spacecraft, the Wilkinson Microwave Anisotropy Probe and other probes. Measurements of the cosmic background radiation give the cooling time of the universe since the Big Bang, and measurements of the expansion rate of the universe can be used to calculate its approximate age by extrapolating backwards in time.

Big Crunch

The Big Crunch is one of the theoretical scenarios for the ultimate fate of the universe, in which the metric expansion of space eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach zero or causing a reformation of the universe starting with another Big Bang.

Some experimental evidence casts doubt on this theory and suggests that the expansion of the universe is accelerating, rather than being slowed down by gravity. However, more recent research has called this conclusion into question.

Big Rip

In physical cosmology, the Big Rip is a hypothetical cosmological model concerning the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, and even spacetime itself, is progressively torn apart by the expansion of the universe at a certain time in the future. According to the standard model of cosmology the scale factor of the universe is known to be accelerating and, in the future era of cosmological constant dominance, will increase exponentially. However, this expansion is similar for every moment of time (hence the exponential law - the expansion of a local volume is the same number of times over the same time interval), and is characterized by an unchanging, small Hubble constant, effectively ignored by any bound material structures. By contrast in the Big Rip scenario the Hubble constant increases to infinity in a finite time.

The possibility of sudden rip singularity occurs only for hypothetical matter (phantom energy) with implausible physical properties.

Black Hole Initiative

The Black Hole Initiative (BHI) is an interdisciplinary program at Harvard University that includes the fields of Astronomy, Physics and Philosophy, and is claimed to be the first center in the world to focus on the study of black holes. Notable principal participants include: Sheperd Doeleman, Peter Galison, Avi Loeb, Ramesh Narayan, Andrew Strominger and Shing-Tung Yau. The BHI Inauguration was held on 18 April 2016 and was attended by Stephen Hawking; related workshop events were held on 19 April 2016. Robert Dijkgraaf created the mural for the BHI Inauguration.

If determinism — the predictability of the universe — breaks down in black holes, it could break down in other situations. Even worse, if determinism breaks down, we can’t be sure of our past history either. The history books and our memories could just be illusions. It is the past that tells us who we are. Without it, we lose our identity.

Coma Filament

Coma Filament is a galaxy filament. The filament contains the Coma Supercluster of galaxies and forms a part of the CfA2 Great Wall.

Cosmic background radiation

Cosmic background radiation is electromagnetic radiation from the Big Bang. The origin of this radiation depends on the region of the spectrum that is observed. One component is the cosmic microwave background. This component is redshifted photons that have freely streamed from an epoch when the Universe became transparent for the first time to radiation. Its discovery and detailed observations of its properties are considered one of the major confirmations of the Big Bang. The discovery (by chance in 1965) of the cosmic background radiation suggests that the early universe was dominated by a radiation field, a field of extremely high temperature and pressure.The Sunyaev–Zel'dovich effect shows the phenomena of radiant cosmic background radiation interacting with "electron" clouds distorting the spectrum of the radiation.

There is also background radiation in the infrared, x-rays, etc., with different causes, and they can sometimes be resolved into an individual source. See cosmic infrared background and X-ray background. See also cosmic neutrino background and extragalactic background light.

Galaxy filament

In physical cosmology, galaxy filaments (subtypes: supercluster complexes, galaxy walls, and galaxy sheets) are the largest known structures in the universe. They are massive, thread-like formations, with a typical length of 50 to 80 megaparsecs h−1 (163 to 261 million light-years) that form the boundaries between large voids in the universe. Filaments consist of gravitationally bound galaxies. Parts wherein many galaxies are very close to one another (in cosmic terms) are called superclusters.

Galaxy formation and evolution

The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to occur from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang. The simplest model in general agreement with observed phenomena is the Lambda-CDM model—that is, that clustering and merging allows galaxies to accumulate mass, determining both their shape and structure.

Grand unification epoch

In physical cosmology, assuming that nature is described by a Grand Unified Theory, the grand unification epoch was the period in the evolution of the early universe following the Planck epoch, starting at about 10−43 seconds after the Big Bang, in which the temperature of the universe was comparable to the characteristic temperatures of grand unified theories. If the grand unification energy is taken to be 1015 GeV, this corresponds to temperatures higher than 1027 K. During this period, three of the four fundamental interactions—electromagnetism, the strong interaction, and the weak interaction—were unified as the electronuclear force. Gravity had separated from the electronuclear force at the end of the Planck era. During the grand unification epoch, physical characteristics such as mass, charge, flavour and colour charge were meaningless.

The grand unification epoch ended at approximately 10−36 seconds after the Big Bang. At this point several key events took place. The strong force separated from the other fundamental forces.

It is possible that some part of this decay process violated the conservation of baryon number and gave rise to a small excess of matter over antimatter (see baryogenesis). This phase transition is also thought to have triggered the process of cosmic inflation that dominated the development of the universe during the following inflationary epoch.

Graphical timeline of the Big Bang

This timeline of the Big Bang shows a sequence of events as currently theorized by scientists.

It is a logarithmic scale that shows second instead of second. For example, one microsecond is . To convert −30 read on the scale to second calculate second = one millisecond. On a logarithmic time scale a step lasts ten times longer than the previous step.

Hadron epoch

In physical cosmology, the hadron epoch was the period in the evolution of the early universe during which the mass of the universe was dominated by hadrons. It started approximately 10−6 seconds after the Big Bang, when the temperature of the universe had fallen sufficiently to allow the quarks from the preceding quark epoch to bind together into hadrons. Initially the temperature was high enough to allow the formation of hadron/anti-hadron pairs, which kept matter and anti-matter in thermal equilibrium. However, as the temperature of the universe continued to fall, hadron/anti-hadron pairs were no longer produced. Most of the hadrons and anti-hadrons were then eliminated in annihilation reactions, leaving a small residue of hadrons. The elimination of anti-hadrons was completed by one second after the Big Bang, when the following lepton epoch began.

Laniakea Supercluster

The Laniakea Supercluster (Laniakea, Hawaiian for open skies or immense heaven; also called Local Supercluster or Local SCl or sometimes Lenakaeia) is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies. It was defined in September 2014, when a group of astronomers including R. Brent Tully of the University of Hawaii, Hélène Courtois of the University of Lyon, Yehuda Hoffman of the Hebrew University of Jerusalem, and Daniel Pomarède of CEA Université Paris-Saclay published a new way of defining superclusters according to the relative velocities of galaxies. The new definition of the local supercluster subsumes the prior defined local supercluster, the Virgo Supercluster, as an appendage.Follow-up studies suggest that Laniakea is not gravitationally bound; it will disperse rather than continue to maintain itself as an overdensity relative to surrounding areas.

Lepton epoch

In physical cosmology, the lepton epoch was the period in the evolution of the early universe in which the leptons dominated the mass of the universe. It started roughly 1 second after the Big Bang, after the majority of hadrons and anti-hadrons annihilated each other at the end of the hadron epoch. During the lepton epoch the temperature of the universe was still high enough to create lepton/anti-lepton pairs, so leptons and anti-leptons were in thermal equilibrium. Approximately 10 seconds after the Big Bang the temperature of the universe had fallen to the point where lepton/anti-lepton pairs were no longer created. Most leptons and anti-leptons were then eliminated in annihilation reactions, leaving a small residue of leptons. The mass of the universe was then dominated by photons as it entered the following photon epoch.

Marc Aaronson

Marc Aaronson (24 August 1950 – 30 April 1987) was an American astronomer.

Matter power spectrum

The matter power spectrum describes the density contrast of the universe (the difference between the local density and the mean density) as a function of scale. It is the Fourier transform of the matter correlation function. On large scales, gravity competes with cosmic expansion, and structures grow according to linear theory. In this regime, the density contrast field is Gaussian, Fourier modes evolve independently, and the power spectrum is sufficient to completely describe the density field. On small scales, gravitational collapse is non-linear, and can only be computed accurately using N-body simulations. Higher-order statistics are necessary to describe the full field at small scales.

Photon epoch

In physical cosmology, the photon epoch was the period in the evolution of the early universe in which photons dominated the energy of the universe. The photon epoch started after most leptons and anti-leptons were annihilated at the end of the lepton epoch, about 10 seconds after the Big Bang. Atomic nuclei were created in the process of nucleosynthesis which occurred during the first few minutes of the photon epoch. For the remainder of the photon epoch, the universe contained a hot dense plasma of nuclei, electrons and photons. 370,000 years after the Big Bang the temperature of the universe fell to the point where nuclei could combine with electrons to create neutral atoms. As a result, photons no longer interacted frequently with matter, the universe became transparent and the cosmic microwave background radiation was created and then structure formation took place.

Physical computing

Physical computing means building interactive physical systems by the use of software and hardware that can sense and respond to the analog world. While this definition is broad enough to encompass systems such as smart automotive traffic control systems or factory automation processes, it is not commonly used to describe them. In a broader sense, physical computing is a creative framework for understanding human beings' relationship to the digital world. In practical use, the term most often describes handmade art, design or DIY hobby projects that use sensors and microcontrollers to translate analog input to a software system, and/or control electro-mechanical devices such as motors, servos, lighting or other hardware.

Physical Computing intersects the range of activities often referred to in academia and industry as electrical engineering, mechatronics, robotics, computer science, and especially embedded development.

Quark epoch

In physical cosmology the Quark epoch was the period in the evolution of the early universe when the fundamental interactions of gravitation, electromagnetism, the strong interaction and the weak interaction had taken their present forms, but the temperature of the universe was still too high to allow quarks to bind together to form hadrons. The quark epoch began approximately 10−12 seconds after the Big Bang, when the preceding electroweak epoch ended as the electroweak interaction separated into the weak interaction and electromagnetism. During the quark epoch the universe was filled with a dense, hot quark–gluon plasma, containing quarks, leptons and their antiparticles. Collisions between particles were too energetic to allow quarks to combine into mesons or baryons. The quark epoch ended when the universe was about 10−6 seconds old, when the average energy of particle interactions had fallen below the binding energy of hadrons. The following period, when quarks became confined within hadrons, is known as the hadron epoch.

Religious interpretations of the Big Bang theory

Since the emergence of the Big Bang theory as the dominant physical cosmological paradigm, there have been a variety of reactions by religious groups regarding its implications for religious cosmologies. Some accept the scientific evidence at face value, some seek to harmonize the Big Bang with their religious tenets, and some reject or ignore the evidence for the Big Bang theory.

Forms of dark matter
Hypothetical particles
Theories and objects
Search experiments
Potential dark galaxies
Related

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