Scientists investigate dark matter in a virtual universe. Space


A zoom-in, computer-generated simulation for the distribution of dark matter in the universe, also known as the cosmic web. Small, spherical droplets of dark matter that appear scattered throughout the image are identified by scientists as dark matter heels, gravitationally bound structures within which galaxies form. J. Image via Wang; s. Bose / CFA.

Originally published by the Harvard-Smithsonian Center for Astrophysics, headquartered in Cambridge, Massachusetts, on September 2, 2020.

Using the power of supercomputers, an international team of researchers has zoomed in on the smallest clusters of dark matter in a virtual universe. Published in Peer-Review Journal on September 2, 2020 NatureThe study reveals a halo of dark matter as the active regions of the sky, not only with galaxies, but also radiation-emitting collisions that can make it possible to find these aura in the real sky.

Dark Matter – which makes up about 83% of the matter in the universe – is an important player in cosmic evolution, including the formation of galaxies, which evolved as gas and condensed into the core of a vast cluster of Dark Matter. Over time, some haloes formed as clusters of dark matter faded away from the expansion of the universe due to their enormous gravity. The largest dark matter haloes contain massive galaxy clusters – a collection of hundreds of galaxies – and while their properties can be inferred by studying those galaxies, the smallest dark matter haloes, which usually lack a single star, are now Remains a mystery. .

Sownak Bose is one of the lead authors on new research at CfA. he said:

One of the things we learned from our simulations is that gravity leads to ‘clumping’ of dark mantle particles in highly dense regions of the universe, known as dark matter heels. These can essentially be thought of as large wells of gravity filled with particles of dark matter.

We assume that each galaxy in the universe is surrounded by an extended distribution of dark matter, which outstrips the galaxy’s luminous content by a factor of 10 to 100, depending on the type of galaxy. Because this dark matter surrounds every galaxy in every direction, we call it ‘halo’.

A young, intelligent-looking man: glasses, dark hair, bearded eyes.

Sownak Bose is a postdoc at the Institute of Theory and Computation at the Harvard-Smithsonian Center for Astrophysics (CfA). He uses large numerical simulations to study the largest cosmological structures in our universe – called the cosmic web – and the evolution of galaxies. Image via CfA.

In the virtual universe simulated by these scientists, researchers were able to zoom to the surface of the full moon with the accuracy necessary to identify a flea – with a magnification of up to a power of seven, or seven zeros after 10 – the largest. Create highly detailed images from known little to hundreds of virtual dark matter haloes. Bose explained:

Simulations are helpful because they help us not only the overall distribution of dark matter in the universe, but also the detailed internal structure of these dark matter. Establishing the multiplicity and internal structure of the full range of cold matter matter models that can form in a cold dark matter model is of interest because it enables us to calculate how easy it is to detect dark matter in the real universe Can.

While studying the structure of the corona through its simulation, the researchers were met with a surprise: all dark matter haloes, whether large or small, have similar internal structures that are dense at the center and rapidly spreading. There are spreaders. Astronomer G. Wang and lead author of the research at the National Astronomical Observatories (NAOC) in Beijing said:

Several previous studies suggested that the density profile for super-mini haloes would be significantly different from their larger counterparts. Our simulations show that they look similar in a vast array of dark aura and this is truly surprising.

Bose said that even in small charges that do not surround the galaxies:

… our simulation enabled us to imagine the so-called ‘cosmic web’. Where there are filaments of dark matter, one sees small matter, near the spherical segments of dark matter, which are themselves corona, and they are so universal in structure that I would give you a million billion times larger Can show a picture of a galaxy cluster. The sun, and an earth-mass is a million times smaller than the sun, and you won’t be able to tell which one.

An old Chinese man with glasses, in a sweater and tie.

Ji Wang, the astronomer at the National Astronomical Observatories in Beijing, is the lead author on the new research. Image via NOAC.

Although this study results from simulation simulations of dark matter corona, the simulations themselves are informed by actual observational data. For astronomers, this means that the study can be repeated against the actual night sky that has been given the correct technique. Bose said:

The initial conditions known in our simulations are based on actual observational data from the Planck satellite’s cosmic microwave background radiation measurements, which tell us what the structure of the universe is and how deep matter is.

During the study, researchers tested a feature of the Dark Matter halo, which could make them easier to find in the real night sky: particle collisions. Current theory suggests that dark matter particles hitting near the center of the corona can burst into a violent explosion of high-energy gamma radiation, possibly making dark matter charges detectable by gamma-rays and other telescopes . Bose said:

Exactly how radiation will be detected depends on the exact properties of the dark matter particle. In the case of weakening of massively weak particles (WIMPs), which are among the leading candidates in the standard cold dark matter diagram [currently the most popular theory among scientists to explain the nature of dark matter], Gamma radiation is typically generated in GeV [gigaelectronvolt] Range. Fermi data make claims for a galactic center of excess of GeV-scale gamma radiation, which may be caused by dark matter or perhaps pulsars.

Wang said:

Ground-based telescopes such as the very energetic Radiation Imaging Telescope Array System (VERITAS) can also be used for this purpose. And, pointing telescopes into galaxies other than our own can also help, because this radiation must be produced in the hells of all dark matter

With the knowledge from our simulations, we can evaluate many different instruments for detecting halo – gamma-ray, gravitational lensing, dynamics. These methods are promising to work to shed light on the nature of all dark matter particles.

The study results provide a pathway for current and future researchers to better understand what is there, whether we can see it or not. Bose said:

Understanding the nature of Dark Matter is one of the sacred grills of cosmology. When we know that it dominates the gravitation of the universe, we know very little about its fundamental properties: how heavy an individual particle is, what kind of interaction, if any, it would cause to the normal matter. With, etc. Through computer simulation, we have. To know about its fundamental role in the creation of structure in our universe. In particular, we have come to know that without dark matter, nothing will look the way our universe does right now. There will be no galaxy, no stars, no planets and no life.

This is because Dark Matter acts as an invisible skeletal structure that holds the visible universe around us.

Web structure with long strands with short shiny dots.

A zoom-in, computer-generated simulation for the distribution of dark matter in the universe, also known as the cosmic web. Inset: The highest level of magnification appears as small yellow drops, or earth-mass dark matter as they would appear in the universe today. When they are present in the corresponding area of ​​the background, they appear only after zooming several times. This is the first time these objects have ever been produced in numerical simulations. J. Wang / s. Image via Bose / CFA.

Bottom Line: Researchers in the US and China used a supercomputer to investigate the halo of dark matter in a virtual universe. This work reveals a halo of dark matter as the active regions of the sky, not only with galaxies, but also radiation-emitting collisions that can make it possible to find dark matter haloes in the real sky.

Source: Universal structure of dark matter, rests on a huge range of 20 orders of magnitude

Via CFA

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