Unit 10: Dark Matter
... Dark matter is something beyond the stuff we encounter here on Earth. We all consist of neutrons, protons, and electrons, and our particle physics experiments with cosmic rays and accelerators tell us that a whole set of particles interact with each other to make up the world we see. As we learned i ...
... Dark matter is something beyond the stuff we encounter here on Earth. We all consist of neutrons, protons, and electrons, and our particle physics experiments with cosmic rays and accelerators tell us that a whole set of particles interact with each other to make up the world we see. As we learned i ...
Understanding the Astrophysics of Galaxy Evolution: the role of
... Over the past decade and a half, our observational understanding of galaxy evolution has grown enormously. Steidel and collaborators demonstrated that colour selection techniques allow so-called Lyman Break galaxies (LBGs) to be isolated efficiently at redshifts ∼ 3, thus breaking the z = 1 redshift ...
... Over the past decade and a half, our observational understanding of galaxy evolution has grown enormously. Steidel and collaborators demonstrated that colour selection techniques allow so-called Lyman Break galaxies (LBGs) to be isolated efficiently at redshifts ∼ 3, thus breaking the z = 1 redshift ...
Gravitational Lenses and Unconventional Gravity Theories
... individual galaxy (see Blandford & Naryan 1992), there is no indication of a discrepancy between the lensing and luminous masses (Breimer & Sanders 1993). This is not surprising because, typically, the impact parameter of photons forming multiple images is only a few Kpc, and there is convincing ev ...
... individual galaxy (see Blandford & Naryan 1992), there is no indication of a discrepancy between the lensing and luminous masses (Breimer & Sanders 1993). This is not surprising because, typically, the impact parameter of photons forming multiple images is only a few Kpc, and there is convincing ev ...
Galaxy Formation
... • galaxies are receding from us with speed proportional to their distance • expansion is the same for all observers 2. The microwave background radiation ...
... • galaxies are receding from us with speed proportional to their distance • expansion is the same for all observers 2. The microwave background radiation ...
Galaxies - Stockton University
... In the Solar neighborhood, an average main-sequence star (excluding binary stars) is separated by of order 107 times its size from its nearest neighbors (1 Solar Radius vs. 1 pc). Galaxies on the other hand have sizes ranging from 1 to 100 Kpc, but are separated by of order 1 to 10 Mpc from their ne ...
... In the Solar neighborhood, an average main-sequence star (excluding binary stars) is separated by of order 107 times its size from its nearest neighbors (1 Solar Radius vs. 1 pc). Galaxies on the other hand have sizes ranging from 1 to 100 Kpc, but are separated by of order 1 to 10 Mpc from their ne ...
efectos de la presión hidrostática sobre la energía de enlace para
... under the discrete symmetry Z 2 , are added to the SM. As a result (a) the new Higgs doublet has a zero vev and there is no Dirac mass term. Thus, neutrinos remain massless at tree level; (b) the lightest particle in the spectrum, fermion in our case, is stable and therefore, in principle, can be a ...
... under the discrete symmetry Z 2 , are added to the SM. As a result (a) the new Higgs doublet has a zero vev and there is no Dirac mass term. Thus, neutrinos remain massless at tree level; (b) the lightest particle in the spectrum, fermion in our case, is stable and therefore, in principle, can be a ...
Archaeology of the Milky Way - Max-Planck
... the formation and evolution of galaxies and is thus a key research topic in cosmology, and the research focus of the team working with Hans-Walter Rix, Director at the Max Planck Institute for Astronomy in Heidelberg. The researchers recently found indications that quite a number of earlier ideas ab ...
... the formation and evolution of galaxies and is thus a key research topic in cosmology, and the research focus of the team working with Hans-Walter Rix, Director at the Max Planck Institute for Astronomy in Heidelberg. The researchers recently found indications that quite a number of earlier ideas ab ...
searching for dark matter annihilation in the smith high
... recent stripping event. Moreover, tidal stripping during the most recent interaction with the Galactic plane is expected to have decreased the dark matter mass by approximately a factor of two, compared to a factor of five decrease in the gas content. This indicates that the Smith Cloud is currently ...
... recent stripping event. Moreover, tidal stripping during the most recent interaction with the Galactic plane is expected to have decreased the dark matter mass by approximately a factor of two, compared to a factor of five decrease in the gas content. This indicates that the Smith Cloud is currently ...
" Galaxy," Defined
... for all purposes, we propose a physically motivated definition that will facilitate studies of galaxies both in and out of a cosmological context: A galaxy is a gravitationally bound collection of stars whose properties cannot be explained by a combination of baryons and Newton’s laws of gravity. In ...
... for all purposes, we propose a physically motivated definition that will facilitate studies of galaxies both in and out of a cosmological context: A galaxy is a gravitationally bound collection of stars whose properties cannot be explained by a combination of baryons and Newton’s laws of gravity. In ...
Galactic Encounters: The Dynamics of Mergers and Satellite Accretion
... galaxies merge, direct hits of stars are very unlikely. This shouldn’t be surprising, considering how small the fraction of the area filled by stars in a galaxy is. For the solar neighbourhood we typically have 20 stars/pc3 and the radius of each star is about 0.2Rsun on average. So the fractional a ...
... galaxies merge, direct hits of stars are very unlikely. This shouldn’t be surprising, considering how small the fraction of the area filled by stars in a galaxy is. For the solar neighbourhood we typically have 20 stars/pc3 and the radius of each star is about 0.2Rsun on average. So the fractional a ...
Fossil Galaxies
... predict that thousands of dwarf galaxies should currently exist in orbit around our Milky Way galaxy. However, only a few dozen dwarf galaxies have been observed. Called the “missing satellite problem,” one possible explanation is that there has been very little or, perhaps, no star formation in the ...
... predict that thousands of dwarf galaxies should currently exist in orbit around our Milky Way galaxy. However, only a few dozen dwarf galaxies have been observed. Called the “missing satellite problem,” one possible explanation is that there has been very little or, perhaps, no star formation in the ...
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.