Gravity in Quantum Scales
Description of Dark Matter/Energy;
|| Since any model of structure formation must explain both the tiny ripples in the Cosmic Microwave Background temperature across the sky, and the large-scale structures we see in the universe today, the combination of these two probes is especially powerful. Together they enable us to probe the spectrum of fluctuations over about 4 decades in length scale and its evolution over almost the entire age of the universe. This information, plus information from smaller, high-red-shift very early time, surveys of galaxies and neutral gas will enable us to piece together the mechanism for the formation and mode of evolution of all of the structure we see around us in the universe.
Galaxy surveys with well defined selection criteria enable us to extract information about the clustering pattern. (Surveys during the early 1980's showed that galaxies are not distributed randomly throughout the Universe. They are found to lie in clusters, filaments, bubbles and sheet like structures).
To characterize the distribution of galaxies, a number of statistical tools have been developed. The most widely used approach to quantifying the degree of clustering observed is to measure the correlation functions. For example the two-point correlation function is the probability, in excess of random, of finding a galaxy at a fixed distance from a random neighbor. Beyond this measurement, one can investigate a higher order correlation of functions, for example the distribution of counts in cells: the distribution of the number of galaxies found in cells of a given size which one lays down atop the survey.
As the new era of surveys catalogues the 3D positions of millions of galaxies the biggest uncertainty will become the mapping from the clustering of different galaxy types to the clustering of the underlying matter which the theories most straightforwardly predict. There is no reason to expect that the galaxies will trace the matter exactly. The fact that the light does not trace the `mass' is usually called galaxy bias (one of several technical uses of the term bias in large-scale structure) and poses a fundamental problem on which much work remains to be done.
Clusters of galaxies are the largest gravitationally bound systems in the universe, with sizes of a few Mpc (a Mpc is about 3 million light-years). A typical cluster contains hundreds or thousands of galaxies, but most of the mass is in the form of a hot intra-cluster gas. This gas is heated to high temperatures in the potential well of the cluster. Clusters are rare objects: less than 1 in 10 galaxies in the universe resides in clusters, the rest are said to be field galaxies.
The two most obvious means of studying clusters of galaxies are by observing the light emitted from the constituent galaxies or the X-ray emission from the hot intra-cluster gas. Recently it has proved possible to observe clusters of galaxies in two other ways which (in combination with the traditional methods) should prove exceptionally powerful. The first, known as the Sunyaev-Zeldovich effect after the people who first proposed it, is to observe the cluster as a hole in the microwave sky. Due to the free electrons in the hot intra-cluster gas, photons from the microwave background are up scattered in energy. This leaves a decrement or deficit in the number of photons at low-frequency or a hole in the microwave sky.
Obviously clusters trace out the large-scale structure of the universe just as galaxies do. However there are several cluster properties that are interesting in and of them.
The present number density of clusters is a measure of the amplitude of fluctuations in the universe on scale of around 8Mpc.
The evolution of this number density (vs mass or temperature) with red-shift can determine the mass density parameter Omega. Recently it has been argued that the number of giant arcs, caused by strong gravitational lensing of background galaxies is caused by the cores of clusters.
The Bolshoi supercomputer simulation, the most accurate and detailed large cosmological simulation run to date, gives physicists and astronomers a powerful new tool for understanding such cosmic mysteries as galaxy formation, dark matter, and dark energy.
To the scientists, this was a challenge to demonstrate and they did a simulation (The Bolshoi supercomputer simulation, the most accurate and detailed large cosmological simulation) traces the evolution of the large-scale structure of the universe, including the evolution and distribution of the dark matter halos in which galaxies coalesced and grew. Initial studies show good agreement between the simulation's predictions and astronomers' observations.
These huge cosmological simulations are essential for interpreting the results of ongoing astronomical observations and for planning the new large surveys of the universe that are expected to help determine the nature of the mysterious dark energy.
The standard explanation for how the universe evolved after the Big Bang is known as the Lambda Cold Dark Matter model, and it is the theoretical basis for the Bolshoi simulation. According to this model, gravity acted initially on slight density fluctuations present shortly after the Big Bang to pull together the first clumps of dark matter.
Although the nature of dark matter remains a mystery, it accounts for about 82 percent of the matter in the universe. As a result, the evolution of structure in the universe has been driven by the gravitational interactions of dark matter. The ordinary matter that forms stars and planets has fallen into the gravitational wells created by clumps of dark matter, giving rise to galaxies in the centers of dark matter halos.
Also we have a new and different technique that allowed astronomers to observe radio light from hydrogen gas dating from when the universe was about half its current age. This was the furthest scientist have ever observed such gas.
The method, called intensity mapping, could eventually reveal how such a large-scale structure has changed over the last few billion years, giving insight into which theory of dark energy is the most accurate.
The project mapped hydrogen gas to greater cosmic distances than ever before, and shows that the techniques they developed can be used to map huge volumes of the Universe in three dimensions and to test the competing theories of dark energy.
Since the early part of the 20th century, astronomers have traced the expansion of the universe by observing galaxies. The new technique allows to skip the galaxy-detection step and gather radio emissions from a thousand galaxies at a time, as well as all the dimly glowing material between them.
This is a demonstration of an important technique that has great promise for future studies of the evolution of large-scale structure in the Universe.
Also we can see the black holes in the picture of the large scale structure, we hear news of a new study of the early universe showing that black holes formed earlier than expected and that structure in the pattern of galaxies extends to larger distances than expected.
A key feature of this model is the idea that the birth of black holes in the centers of supergiant galaxies is strongly influenced by the large-scale distribution of matter in the universe. This conjecture can successfully explain two observed phenomena: the alignment of the radio, optical and infrared axes of high-red-shift radio galaxies, and the alignment of present day CD galaxies with their environments.
The ruling paradigm says that galaxies formed when hydrogen gas and dark matter slowly clumped together under its gravitational pull. Stars were formed which continued to collapse together to form galaxies. The early stars which were large would die quickly and form black holes which would coalesce to form super-massive black holes at the centers of galaxies.
The process was seeded by density perturbations in the gas that existed at the time of the last light scattering. The effects of these perturbations are seen in the cosmic microwave background and are very familiar to cosmologists. They are believed to be due to fluctuations during the inflationary epoch and they have the right scale invariant spectrum to fit that hypothesis.
It predicts that the black holes form after the stars, yet we see quasars appearing in the early universe containing huge black holes that must have formed much earlier.
We also observe structure in the distribution of galaxies that extends out to very large scales. This is not predicted by the cold dark matter theory of structure formation. An example is the Great Sloan Wall, a vast planar structure covering 5% of the size of the observable universe.
One possible answer is that they did not form through gravitational collapse at all, but instead by a process of caustic focusing of dark matter by gravitational waves.
We know very little about how the inflationary epoch ended. The vacuum state would have changed as the inflationary scalar field dropped into a broken phase. There may have been a phase transition but it may have been a soft second order transition or even a smooth crossover. We don’t even know when it happened.
It may have been the electro-weak transition or something earlier.
It is likely that the transition did not happen simultaneously at all points in space. Fluctuations would mean that inflation continued a little longer in some places than others. This would leave a remnant gravitational wave background in the universe which in time would have cooled and weakened as the universe expanded more slowly. It would be hard to detect directly today because of its very low frequency and weak amplitude, but in the early universe during baryogenesis it would have been stronger.
||
Galaxy surveys with well defined selection criteria enable us to extract information about the clustering pattern. (Surveys during the early 1980's showed that galaxies are not distributed randomly throughout the Universe. They are found to lie in clusters, filaments, bubbles and sheet like structures).
To characterize the distribution of galaxies, a number of statistical tools have been developed. The most widely used approach to quantifying the degree of clustering observed is to measure the correlation functions. For example the two-point correlation function is the probability, in excess of random, of finding a galaxy at a fixed distance from a random neighbor. Beyond this measurement, one can investigate a higher order correlation of functions, for example the distribution of counts in cells: the distribution of the number of galaxies found in cells of a given size which one lays down atop the survey.
As the new era of surveys catalogues the 3D positions of millions of galaxies the biggest uncertainty will become the mapping from the clustering of different galaxy types to the clustering of the underlying matter which the theories most straightforwardly predict. There is no reason to expect that the galaxies will trace the matter exactly. The fact that the light does not trace the `mass' is usually called galaxy bias (one of several technical uses of the term bias in large-scale structure) and poses a fundamental problem on which much work remains to be done.
Clusters of galaxies are the largest gravitationally bound systems in the universe, with sizes of a few Mpc (a Mpc is about 3 million light-years). A typical cluster contains hundreds or thousands of galaxies, but most of the mass is in the form of a hot intra-cluster gas. This gas is heated to high temperatures in the potential well of the cluster. Clusters are rare objects: less than 1 in 10 galaxies in the universe resides in clusters, the rest are said to be field galaxies.
The two most obvious means of studying clusters of galaxies are by observing the light emitted from the constituent galaxies or the X-ray emission from the hot intra-cluster gas. Recently it has proved possible to observe clusters of galaxies in two other ways which (in combination with the traditional methods) should prove exceptionally powerful. The first, known as the Sunyaev-Zeldovich effect after the people who first proposed it, is to observe the cluster as a hole in the microwave sky. Due to the free electrons in the hot intra-cluster gas, photons from the microwave background are up scattered in energy. This leaves a decrement or deficit in the number of photons at low-frequency or a hole in the microwave sky.
Obviously clusters trace out the large-scale structure of the universe just as galaxies do. However there are several cluster properties that are interesting in and of them.
The present number density of clusters is a measure of the amplitude of fluctuations in the universe on scale of around 8Mpc.
The evolution of this number density (vs mass or temperature) with red-shift can determine the mass density parameter Omega. Recently it has been argued that the number of giant arcs, caused by strong gravitational lensing of background galaxies is caused by the cores of clusters.
The Bolshoi supercomputer simulation, the most accurate and detailed large cosmological simulation run to date, gives physicists and astronomers a powerful new tool for understanding such cosmic mysteries as galaxy formation, dark matter, and dark energy.
To the scientists, this was a challenge to demonstrate and they did a simulation (The Bolshoi supercomputer simulation, the most accurate and detailed large cosmological simulation) traces the evolution of the large-scale structure of the universe, including the evolution and distribution of the dark matter halos in which galaxies coalesced and grew. Initial studies show good agreement between the simulation's predictions and astronomers' observations.
These huge cosmological simulations are essential for interpreting the results of ongoing astronomical observations and for planning the new large surveys of the universe that are expected to help determine the nature of the mysterious dark energy.
The standard explanation for how the universe evolved after the Big Bang is known as the Lambda Cold Dark Matter model, and it is the theoretical basis for the Bolshoi simulation. According to this model, gravity acted initially on slight density fluctuations present shortly after the Big Bang to pull together the first clumps of dark matter.
Although the nature of dark matter remains a mystery, it accounts for about 82 percent of the matter in the universe. As a result, the evolution of structure in the universe has been driven by the gravitational interactions of dark matter. The ordinary matter that forms stars and planets has fallen into the gravitational wells created by clumps of dark matter, giving rise to galaxies in the centers of dark matter halos.
Also we have a new and different technique that allowed astronomers to observe radio light from hydrogen gas dating from when the universe was about half its current age. This was the furthest scientist have ever observed such gas.
The method, called intensity mapping, could eventually reveal how such a large-scale structure has changed over the last few billion years, giving insight into which theory of dark energy is the most accurate.
The project mapped hydrogen gas to greater cosmic distances than ever before, and shows that the techniques they developed can be used to map huge volumes of the Universe in three dimensions and to test the competing theories of dark energy.
Since the early part of the 20th century, astronomers have traced the expansion of the universe by observing galaxies. The new technique allows to skip the galaxy-detection step and gather radio emissions from a thousand galaxies at a time, as well as all the dimly glowing material between them.
This is a demonstration of an important technique that has great promise for future studies of the evolution of large-scale structure in the Universe.
Also we can see the black holes in the picture of the large scale structure, we hear news of a new study of the early universe showing that black holes formed earlier than expected and that structure in the pattern of galaxies extends to larger distances than expected.
A key feature of this model is the idea that the birth of black holes in the centers of supergiant galaxies is strongly influenced by the large-scale distribution of matter in the universe. This conjecture can successfully explain two observed phenomena: the alignment of the radio, optical and infrared axes of high-red-shift radio galaxies, and the alignment of present day CD galaxies with their environments.
The ruling paradigm says that galaxies formed when hydrogen gas and dark matter slowly clumped together under its gravitational pull. Stars were formed which continued to collapse together to form galaxies. The early stars which were large would die quickly and form black holes which would coalesce to form super-massive black holes at the centers of galaxies.
The process was seeded by density perturbations in the gas that existed at the time of the last light scattering. The effects of these perturbations are seen in the cosmic microwave background and are very familiar to cosmologists. They are believed to be due to fluctuations during the inflationary epoch and they have the right scale invariant spectrum to fit that hypothesis.
It predicts that the black holes form after the stars, yet we see quasars appearing in the early universe containing huge black holes that must have formed much earlier.
We also observe structure in the distribution of galaxies that extends out to very large scales. This is not predicted by the cold dark matter theory of structure formation. An example is the Great Sloan Wall, a vast planar structure covering 5% of the size of the observable universe.
One possible answer is that they did not form through gravitational collapse at all, but instead by a process of caustic focusing of dark matter by gravitational waves.
We know very little about how the inflationary epoch ended. The vacuum state would have changed as the inflationary scalar field dropped into a broken phase. There may have been a phase transition but it may have been a soft second order transition or even a smooth crossover. We don’t even know when it happened.
It may have been the electro-weak transition or something earlier.
It is likely that the transition did not happen simultaneously at all points in space. Fluctuations would mean that inflation continued a little longer in some places than others. This would leave a remnant gravitational wave background in the universe which in time would have cooled and weakened as the universe expanded more slowly. It would be hard to detect directly today because of its very low frequency and weak amplitude, but in the early universe during baryogenesis it would have been stronger.
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- - To be continue…
Physicsism will complete it by studying on Expanding of Universe And what is relevance between Red-Shift & Fluctuations of elementary particle at Edge of Universe with Quantum Information concepts…
we don have good researches or discussions that compare information and dark matter Or look at dark matter from information peephole.
(For example miniµ black hole had been made when physicist look at the black holes informational. Not exactly base on Q.information theory But that was good for first step. )
Now, I want ur opinion and viewpoint about dark matter/energy & Q.information theory,
And also Red-shift…
What r the effects of information at red-shift?
...
we don have good researches or discussions that compare information and dark matter Or look at dark matter from information peephole.
(For example miniµ black hole had been made when physicist look at the black holes informational. Not exactly base on Q.information theory But that was good for first step. )
Now, I want ur opinion and viewpoint about dark matter/energy & Q.information theory,
And also Red-shift…
What r the effects of information at red-shift?
...
