Dark Matter: Observational Constraints Properties of Dark Matter:
... • This much HI is easily observed in the 21-cm line of atomic hydrogen • Hot, X-ray emitting gas is observed to be insufficient • Warm, 104 K ionized gas emits by bremstrahlung. If in hydrostatic equilibrium, central regions would be dense enough to be easily observed. • Molecular gas must be H2; la ...
... • This much HI is easily observed in the 21-cm line of atomic hydrogen • Hot, X-ray emitting gas is observed to be insufficient • Warm, 104 K ionized gas emits by bremstrahlung. If in hydrostatic equilibrium, central regions would be dense enough to be easily observed. • Molecular gas must be H2; la ...
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... Forward-looking statements are not statements of historical fact and actual events and results may differ materially from those described in the forward looking statements as a result of a variety of risks, uncertainties and other factors. Forward-looking statements are inherently subject to busines ...
... Forward-looking statements are not statements of historical fact and actual events and results may differ materially from those described in the forward looking statements as a result of a variety of risks, uncertainties and other factors. Forward-looking statements are inherently subject to busines ...
Exploration Drilling Mt Cattlin North Project
... Forward-looking statements are not statements of historical fact and actual events and results may differ materially from those described in the forward looking statements as a result of a variety of risks, uncertainties and other factors. Forward-looking statements are inherently subject to busines ...
... Forward-looking statements are not statements of historical fact and actual events and results may differ materially from those described in the forward looking statements as a result of a variety of risks, uncertainties and other factors. Forward-looking statements are inherently subject to busines ...
The cosmic-ray / gamma-ray / synchrotron / magnetic
... Milky Way is a potentially interesting datum on FIR-radio correlation because ... We know much more about our Galaxy than external galaxies: * cosmic rays directly measured * gamma rays mapped in detail * synchrotron mapped in detail * magnetic fields measured so study of the Galaxy allows a better ...
... Milky Way is a potentially interesting datum on FIR-radio correlation because ... We know much more about our Galaxy than external galaxies: * cosmic rays directly measured * gamma rays mapped in detail * synchrotron mapped in detail * magnetic fields measured so study of the Galaxy allows a better ...
Searching for stars in high-velocity clouds
... a special environment, and so it is an important indicator of the form of the field galaxy luminosity function. A lack of stars within HVCs does not rule out the scenario proposed by Braun & Burton (1999) and Blitz et al. (1999), but it does rule out HVCs being of the same class of object as the oth ...
... a special environment, and so it is an important indicator of the form of the field galaxy luminosity function. A lack of stars within HVCs does not rule out the scenario proposed by Braun & Burton (1999) and Blitz et al. (1999), but it does rule out HVCs being of the same class of object as the oth ...
Astro 6590: Galaxies and the Universe Astro
... Spiral arms • We easily see these spiral arms because they contain numerous bright O and B stars which illuminate dust in the arms. • However, stars in total seem to be evenly distributed throughout the disk. • The density contrast is only of order 10%. The blue image shows young star-forming regio ...
... Spiral arms • We easily see these spiral arms because they contain numerous bright O and B stars which illuminate dust in the arms. • However, stars in total seem to be evenly distributed throughout the disk. • The density contrast is only of order 10%. The blue image shows young star-forming regio ...
Part1
... Young/Old Stars, Gas (HII, HI, H2), Dark Matter 3. What does the zoomed-out SED of a galaxy look like? ...
... Young/Old Stars, Gas (HII, HI, H2), Dark Matter 3. What does the zoomed-out SED of a galaxy look like? ...
The Red-Sequence Cluster Survey
... Discretionary Time, soon after the cluster was discovered. This initial spectroscopy demonstrated that the cluster was at z = 0.773, and showed that one of the arcs (the arc labelled ’C’, visible in Figure 5) was extremely distant, at a redshift of 4.8786 (Gladders et al. 2002). The FORS spectrum of ...
... Discretionary Time, soon after the cluster was discovered. This initial spectroscopy demonstrated that the cluster was at z = 0.773, and showed that one of the arcs (the arc labelled ’C’, visible in Figure 5) was extremely distant, at a redshift of 4.8786 (Gladders et al. 2002). The FORS spectrum of ...
Stars and the Milky Way
... • the Milky Way is made up of over 200 billion stars Other facts about the Milky Way • The Sun is just one of the stars in the Milky Way. • It is called the Milky Way because when astronomers looked up at the sky, they saw a line of light that looked like some milk had been spilt. • Stars in our Mil ...
... • the Milky Way is made up of over 200 billion stars Other facts about the Milky Way • The Sun is just one of the stars in the Milky Way. • It is called the Milky Way because when astronomers looked up at the sky, they saw a line of light that looked like some milk had been spilt. • Stars in our Mil ...
Frieman-Dark
... constant (vacuum energy) with w=−1 was wrong once (Cf. inflation): that isn’t a strong argument for it being correct now • Cosmological constant problem (why is vacuum energy density not 120 orders of magnitude larger?) is not necessarily informative for modelbuilding • Some alternatives to Λ (Cf. q ...
... constant (vacuum energy) with w=−1 was wrong once (Cf. inflation): that isn’t a strong argument for it being correct now • Cosmological constant problem (why is vacuum energy density not 120 orders of magnitude larger?) is not necessarily informative for modelbuilding • Some alternatives to Λ (Cf. q ...
Messier 87
Messier 87 (also known as Virgo A or NGC 4486, and generally abbreviated to M87) is a supergiant elliptical galaxy in the constellation Virgo. One of the most massive galaxies in the local universe, it is notable for its large population of globular clusters—M87 contains about 12,000 compared to the 150-200 orbiting the Milky Way—and its jet of energetic plasma that originates at the core and extends outward at least 1,500 parsecs (4,900 light-years), travelling at relativistic speed. It is one of the brightest radio sources in the sky, and is a popular target for both amateur astronomy observations and professional astronomy study.French astronomer Charles Messier discovered M87 in 1781, cataloguing it as a nebulous feature while searching for objects that would confuse comet hunters. The second brightest galaxy within the northern Virgo Cluster, M87 is located about 16.4 million parsecs (53.5 million light-years) from Earth. Unlike a disk-shaped spiral galaxy, M87 has no distinctive dust lanes. Instead, it has an almost featureless, ellipsoidal shape typical of most giant elliptical galaxies, diminishing in luminosity with distance from the centre. Forming around one sixth of M87's mass, the stars in this galaxy have a nearly spherically symmetric distribution, their density decreasing with increasing distance from the core. At the core is a supermassive black hole, which forms the primary component of an active galactic nucleus. This object is a strong source of multiwavelength radiation, particularly radio waves. M87's galactic envelope extends out to a radius of about 150 kiloparsecs (490,000 light-years), where it has been truncated—possibly by an encounter with another galaxy. Between the stars is a diffuse interstellar medium of gas that has been chemically enriched by elements emitted from evolved stars.