The fine-scale structure of dark matter halos
... same object at varying resolution -- are different in simulations of different objects These are potentially observable fossils of the formation process ...
... same object at varying resolution -- are different in simulations of different objects These are potentially observable fossils of the formation process ...
Pocket: The Ten Greatest Steps Of The Last Ten Decades
... made of. Data from COBE was superseded by WMAP, which in turn has been improved upon by Planck. In addition, large-scale structure data from big galaxy surveys (like 2dF and SDSS) and distant supernova data has all combined to give us our modern picture of the Universe: 0.01% radiation in the form o ...
... made of. Data from COBE was superseded by WMAP, which in turn has been improved upon by Planck. In addition, large-scale structure data from big galaxy surveys (like 2dF and SDSS) and distant supernova data has all combined to give us our modern picture of the Universe: 0.01% radiation in the form o ...
Dark bursts - indico in2p3
... GRB 111215A, AVhost > 8.5m, Zauderer+ 2013). The combination of radio and X-ray data allows to robustly determine the required extinction, instead of simply assuming an optical to X-ray spectral index. Millimeter observations of afterglows with JVLA, ALMA, PdB IRAM etc. allow to determine subarcseco ...
... GRB 111215A, AVhost > 8.5m, Zauderer+ 2013). The combination of radio and X-ray data allows to robustly determine the required extinction, instead of simply assuming an optical to X-ray spectral index. Millimeter observations of afterglows with JVLA, ALMA, PdB IRAM etc. allow to determine subarcseco ...
Introduction to Dark Matter
... early 1980s. Faber & Lin (1983) studied dwarf spheroidals and found them to contain large amounts of dark matter. Subsequent studies (for a review, see e.g. Mateo 1998) have in fact shown that dwarf galaxies have higher massto-light ratios than normal galaxies. Smaller stellar populations, like glob ...
... early 1980s. Faber & Lin (1983) studied dwarf spheroidals and found them to contain large amounts of dark matter. Subsequent studies (for a review, see e.g. Mateo 1998) have in fact shown that dwarf galaxies have higher massto-light ratios than normal galaxies. Smaller stellar populations, like glob ...
Chapter 14: The Milky Way Galaxy
... Milky Way (from Earth), we see light from hydrogen atoms Doppler shifted by different amounts – this Doppler shift is used to determine how fast the stars and gas of the disk are moving (rotating). ...
... Milky Way (from Earth), we see light from hydrogen atoms Doppler shifted by different amounts – this Doppler shift is used to determine how fast the stars and gas of the disk are moving (rotating). ...
Galaxy interaction and transformation
... in the universe, with masses of about 1014 − 1015 M , and velocity dispersions of about 1000 km s−1. Many clusters are also found to contain large amount of hot X-ray gas. Thus, galaxies in a cluster can be affected by the cluster environment in three different ways: • ram-pressure stripping of thei ...
... in the universe, with masses of about 1014 − 1015 M , and velocity dispersions of about 1000 km s−1. Many clusters are also found to contain large amount of hot X-ray gas. Thus, galaxies in a cluster can be affected by the cluster environment in three different ways: • ram-pressure stripping of thei ...
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.