Galaxies
... • It depends how fast the gas is used up to form galaxies • If star formation is fast, no gas is left elliptical galaxy • If star formation is slow, gas forms disk spiral galaxy ...
... • It depends how fast the gas is used up to form galaxies • If star formation is fast, no gas is left elliptical galaxy • If star formation is slow, gas forms disk spiral galaxy ...
The Evolution of Galaxy - Tufts Institute of Cosmology
... orbiting so fast that their collective mass could not provide enough gravity to hold them all together. The clusters had to be nearly 100 times as heavy as the visible galaxies, or else the galaxies would have torn out of the clusters long ago. The inescapable conclusion was that the clusters were m ...
... orbiting so fast that their collective mass could not provide enough gravity to hold them all together. The clusters had to be nearly 100 times as heavy as the visible galaxies, or else the galaxies would have torn out of the clusters long ago. The inescapable conclusion was that the clusters were m ...
File
... Earth Science 25.3 The Universe Galaxy Clusters: Once astronomers discovered that stars were found in groups, they wondered whether galaxies also were grouped or just randomly distributed among the universe. They found that, like stars, galaxies are grouped in clusters. Some clusters may cont ...
... Earth Science 25.3 The Universe Galaxy Clusters: Once astronomers discovered that stars were found in groups, they wondered whether galaxies also were grouped or just randomly distributed among the universe. They found that, like stars, galaxies are grouped in clusters. Some clusters may cont ...
Planets and Moons - Fraser Heights Chess Club
... and billions of stars held together by gravity. One galaxy can have hundreds of billions of stars and be as large as 200,000 light years across. • Galaxy is derived from the Greek galaxias meaning "milky", a reference to the Milky Way. • Many galaxies are believed to have black holes at their active ...
... and billions of stars held together by gravity. One galaxy can have hundreds of billions of stars and be as large as 200,000 light years across. • Galaxy is derived from the Greek galaxias meaning "milky", a reference to the Milky Way. • Many galaxies are believed to have black holes at their active ...
PH607 – Galaxies
... 7.2 Clusters of Galaxies Clusters are systems a few Mpc across, typically containing at least 50-100 luminous galaxies within the central 1 Mpc Clusters are gravitationally bound Clusters are filled with hot X-ray gas Only ~20% of galaxies live in clusters, most live in groups or in the “fi ...
... 7.2 Clusters of Galaxies Clusters are systems a few Mpc across, typically containing at least 50-100 luminous galaxies within the central 1 Mpc Clusters are gravitationally bound Clusters are filled with hot X-ray gas Only ~20% of galaxies live in clusters, most live in groups or in the “fi ...
Disk Galaxies and problem 3
... where rs is a scale radius (≈ 20 kpc for the MW), which has to be found from computer simulations. The profile scales as r−1 at small radius, but as r−3 at large radius. There is an intermediate range (r ∼ rs ) where the density follows r−2 . There may be an intriguing disk-halo conspiracy. Fig. 4 s ...
... where rs is a scale radius (≈ 20 kpc for the MW), which has to be found from computer simulations. The profile scales as r−1 at small radius, but as r−3 at large radius. There is an intermediate range (r ∼ rs ) where the density follows r−2 . There may be an intriguing disk-halo conspiracy. Fig. 4 s ...
Document
... The Universe must have initially “inflated” in size, expanding many times faster than the speed of light. After this “inflationary period”, the expanding Universe was slowing down (decelerating) due to gravity. At some arbitrary moment, the cosmic expansion inexplicably “jerked” from decelerating to ...
... The Universe must have initially “inflated” in size, expanding many times faster than the speed of light. After this “inflationary period”, the expanding Universe was slowing down (decelerating) due to gravity. At some arbitrary moment, the cosmic expansion inexplicably “jerked” from decelerating to ...
Universe, Dark Energy and Dark Matter
... If a particle emits a photon in the opposite direction of its motion, the photon moves for a while over space cells whose deformation gradient is opposite to the photon motion and the photon has to give part of its energy (mass) to the moving particle. In this case the red shift effect can be observ ...
... If a particle emits a photon in the opposite direction of its motion, the photon moves for a while over space cells whose deformation gradient is opposite to the photon motion and the photon has to give part of its energy (mass) to the moving particle. In this case the red shift effect can be observ ...
New Dark Matter Physics: Clues from Halo Structure
... and therefore the number of the particles), the filtering scale for 1 keV particles is at about k = 3Mpc−1 — small enough to preserve the successful large-scale predictions of CDM but also large enough to impact the substructure problem. Galaxy halo substructure therefore favors a primordial phase d ...
... and therefore the number of the particles), the filtering scale for 1 keV particles is at about k = 3Mpc−1 — small enough to preserve the successful large-scale predictions of CDM but also large enough to impact the substructure problem. Galaxy halo substructure therefore favors a primordial phase d ...
powerpoint - Physics @ IUPUI
... • A group at the University of Minnesota discovered a void a BILLION light years across! • This is something we just cannot explain currently as we expect them to be 50-200 million light years in size. ...
... • A group at the University of Minnesota discovered a void a BILLION light years across! • This is something we just cannot explain currently as we expect them to be 50-200 million light years in size. ...
Dark matter
Dark matter is a hypothetical kind of matter that cannot be seen with telescopes but would account for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, on radiation, and on the large-scale structure of the universe. Dark matter has not been detected directly, making it one of the greatest mysteries in modern astrophysics.Dark matter neither emits nor absorbs light or any other electromagnetic radiation at any significant level. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the known universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy. Thus, dark matter is estimated to constitute 84.5% of the total matter in the universe, while dark energy plus dark matter constitute 95.1% of the total mass–energy content of the universe.Astrophysicists hypothesized the existence of dark matter to account for discrepancies between the mass of large astronomical objects determined from their gravitational effects, and their mass as calculated from the observable matter (stars, gas, and dust) that they can be seen to contain. Their gravitational effects suggest that their masses are much greater than the observable matter survey suggests. Dark matter was postulated by Jan Oort in 1932, albeit based upon insufficient evidence, to account for the orbital velocities of stars in the Milky Way. In 1933, Fritz Zwicky was the first to use the virial theorem to infer the existence of unseen matter, which he referred to as dunkle Materie 'dark matter'. More robust evidence from galaxy rotation curves was discovered by Horace W. Babcock in 1939, but was not attributed to dark matter. The first hypothesis to postulate ""dark matter"" based upon robust evidence was formulated by Vera Rubin and Kent Ford in the 1960s–1970s, using galaxy rotation curves. Subsequently, many other observations have indicated the presence of dark matter in the universe, including gravitational lensing of background objects by galaxy clusters such as the Bullet Cluster, the temperature distribution of hot gas in galaxies and clusters of galaxies and, more recently, the pattern of anisotropies in the cosmic microwave background. According to consensus among cosmologists, dark matter is composed primarily of a not yet characterized type of subatomic particle.The search for this particle, by a variety of means, is one of the major efforts in particle physics today.Although the existence of dark matter is generally accepted by the mainstream scientific community, some alternative theories of gravity have been proposed, such as MOND and TeVeS, which try to account for the anomalous observations without requiring additional matter. However, these theories cannot account for the properties of galaxy clusters.