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 ...
APS Neutrino Study
... of the primordial abundances of deuterium, helium and lithium will improve the precision of BBN, testing both the standard model of particle physics and the framework of standard cosmology. Though less sensitive now, the CMB constraint on the number of neutrino flavors is expected to markedly improv ...
... of the primordial abundances of deuterium, helium and lithium will improve the precision of BBN, testing both the standard model of particle physics and the framework of standard cosmology. Though less sensitive now, the CMB constraint on the number of neutrino flavors is expected to markedly improv ...
Document
... make it the dominant force at large scales. Holds celestial bodies together. Keeps us on the planet, a planet on orbit around a star, a star in a galaxy, a galaxy in a cluster, a cluster in a supercluster, … Also responsible for stellar structure and collapse (supernova) leading formation of neutron ...
... make it the dominant force at large scales. Holds celestial bodies together. Keeps us on the planet, a planet on orbit around a star, a star in a galaxy, a galaxy in a cluster, a cluster in a supercluster, … Also responsible for stellar structure and collapse (supernova) leading formation of neutron ...
III Ionized Hydrogen (HII) Regions
... gaseous nebulae are very different, the physics governing them is basically the same. We will refer to all of these as “HII Regions” generically in this section. The UV, visible and IR spectra of HII regions are very rich in emission lines, primarily collisionally excited lines of metal ions and rec ...
... gaseous nebulae are very different, the physics governing them is basically the same. We will refer to all of these as “HII Regions” generically in this section. The UV, visible and IR spectra of HII regions are very rich in emission lines, primarily collisionally excited lines of metal ions and rec ...
Astrophysical Quark Matter
... QM in pulsar-like compact stars It is still a challenge for astrophysicists to reproduce a successful core-collapse supernova! ...
... QM in pulsar-like compact stars It is still a challenge for astrophysicists to reproduce a successful core-collapse supernova! ...
NASA/TM—2005–213688 National Aeronautics and Space Administration AD33
... The last recommended limit from the National Council on Radiation Protection (NCRP) issued in 1989—0.5 Sv/yr (or 50 rem/yr) to the blood-forming organs of flight crews—considered only the low-Earth orbit environment (dominated by trapped protons and electrons). The dose limit for the ISS has been ad ...
... The last recommended limit from the National Council on Radiation Protection (NCRP) issued in 1989—0.5 Sv/yr (or 50 rem/yr) to the blood-forming organs of flight crews—considered only the low-Earth orbit environment (dominated by trapped protons and electrons). The dose limit for the ISS has been ad ...
TOWARDS AN UNDERSTANDING OF DARK MATTER: PRECISE
... electrons were eagerly trying to combine with protons to form atoms. But these unions wouldn’t last long before a photon would smash into them, breaking the pair apart. Finally at Recombination, the photons had cooled enough that they were no longer able to disrupt these mergers. With electrons tied ...
... electrons were eagerly trying to combine with protons to form atoms. But these unions wouldn’t last long before a photon would smash into them, breaking the pair apart. Finally at Recombination, the photons had cooled enough that they were no longer able to disrupt these mergers. With electrons tied ...
The Animate and the Inanimate
... possible which loses no energy, but in which the kinetic energy remains the same as before, that is to say, an elastic collision; for, in the case of ultimate particles, none of the original energy can be changed into internal motion of the particles. Hence only elastic collision is possible in the ...
... possible which loses no energy, but in which the kinetic energy remains the same as before, that is to say, an elastic collision; for, in the case of ultimate particles, none of the original energy can be changed into internal motion of the particles. Hence only elastic collision is possible in the ...
Sunday, March 24, 2013
... cross "Looks real" (STSci). Again, we see 'blobby' things with faint 'connections' between them, especially when blown up into a severely pixelated image. While Arp complains these 'blobs' are not shaped like the arcs predicted by gravitational lensing, it is important to note that the Hubble observ ...
... cross "Looks real" (STSci). Again, we see 'blobby' things with faint 'connections' between them, especially when blown up into a severely pixelated image. While Arp complains these 'blobs' are not shaped like the arcs predicted by gravitational lensing, it is important to note that the Hubble observ ...
The Animate and the Inanimate
... This irreversible property is found in what is called the second law of thermodynamics. This, taken in its most general aspect, amounts to this: that the energy of the universe is constantly running down to one common level. In other words, where energy of the same variety is present in different de ...
... This irreversible property is found in what is called the second law of thermodynamics. This, taken in its most general aspect, amounts to this: that the energy of the universe is constantly running down to one common level. In other words, where energy of the same variety is present in different de ...
Spectral and Hydrodynamic Modeling of X-Ray Michael Rosenberg
... different from those in a collisional plasma. Like the ionization process itself, excited state population in collisional plasmas arise from electron-ion collisions. More specifically, at high temperatures, collisional ionization will be balanced by dielectronic recombination, wherein the excess ene ...
... different from those in a collisional plasma. Like the ionization process itself, excited state population in collisional plasmas arise from electron-ion collisions. More specifically, at high temperatures, collisional ionization will be balanced by dielectronic recombination, wherein the excess ene ...
Constraining the Contribution of Galaxies and Active Galactic Nuclei
... traviolet luminosity functions (UVLFs) during the EoR are steep and extended down to an absolute UV magnitude of MUV ∼ −16 (Atek et al. 2015; Ishigaki et al. 2015). These facts strengthen the possibility that the high-z galaxies were main ionizing sources of reionization. Robertson et al. (2015) hav ...
... traviolet luminosity functions (UVLFs) during the EoR are steep and extended down to an absolute UV magnitude of MUV ∼ −16 (Atek et al. 2015; Ishigaki et al. 2015). These facts strengthen the possibility that the high-z galaxies were main ionizing sources of reionization. Robertson et al. (2015) hav ...
CHAPTER 4 THE SPATIAL DISTRIBUTION OF GALAXIES 4.13
... Having looked at the properties of individual galaxies – both normal and active – in some detail, it is now appropriate to consider how these galaxies are distributed in space. Surveys of the region outside our own Milky Way show that there are galaxies all around us. Deep field images such as those ...
... Having looked at the properties of individual galaxies – both normal and active – in some detail, it is now appropriate to consider how these galaxies are distributed in space. Surveys of the region outside our own Milky Way show that there are galaxies all around us. Deep field images such as those ...
Rest of the Universe
... Dark matter doesn't appear to be clouds of gas that telescopes wouldn't see, either. Diffuse gas would absorb light from the galaxies that are farther away, and on top of that, ordinary gas would re-emit radiation at longer wavelengths – there'd be a massive radiation of infrared light in the sky. S ...
... Dark matter doesn't appear to be clouds of gas that telescopes wouldn't see, either. Diffuse gas would absorb light from the galaxies that are farther away, and on top of that, ordinary gas would re-emit radiation at longer wavelengths – there'd be a massive radiation of infrared light in the sky. S ...
Inflationary Cosmology
... theories. Unfortunately, this scenario was plagued by its own problems. It works only if the effective potential of the field φ has a very a flat plateau near φ = 0, which is somewhat artificial. In most versions of this scenario the inflaton field has an extremely small coupling constant, so it cou ...
... theories. Unfortunately, this scenario was plagued by its own problems. It works only if the effective potential of the field φ has a very a flat plateau near φ = 0, which is somewhat artificial. In most versions of this scenario the inflaton field has an extremely small coupling constant, so it cou ...
David AJ Seargent
... water. Looking back over so many years, we simply cannot know. But whatever his exact thoughts may have been, the important issue for us is that in these speculations, Thales launched a new endeavor in human though; scientific cosmology or the employment of observation and reason in the bold attempt ...
... water. Looking back over so many years, we simply cannot know. But whatever his exact thoughts may have been, the important issue for us is that in these speculations, Thales launched a new endeavor in human though; scientific cosmology or the employment of observation and reason in the bold attempt ...
Quantum Theory of Neutrino Spin
... where µ0 = e/2m is the Bohr magneton, mν and m are the neutrino and electron masses, respectively. There are also models [2] in which much large values for magnetic moments of neutrinos are predicted. So far, the most stringent laboratory constraints on the electron, muon, and tau neutrino magnetic ...
... where µ0 = e/2m is the Bohr magneton, mν and m are the neutrino and electron masses, respectively. There are also models [2] in which much large values for magnetic moments of neutrinos are predicted. So far, the most stringent laboratory constraints on the electron, muon, and tau neutrino magnetic ...
Cosmology Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015
... Arno Penzias and Robert Woodrow Wilson, at Bell Labs in 1964 ...
... Arno Penzias and Robert Woodrow Wilson, at Bell Labs in 1964 ...
Dark Matter: A Brief Review
... scale. Other particles in these theories could be dark matter if they were the lightest of the new particles (and satisfied cosmological and collider constraints), which depends on where exactly we sit in the rather large theoretical parameter space, but the neutralino and Kaluza-Klein (UED) photon ...
... scale. Other particles in these theories could be dark matter if they were the lightest of the new particles (and satisfied cosmological and collider constraints), which depends on where exactly we sit in the rather large theoretical parameter space, but the neutralino and Kaluza-Klein (UED) photon ...
Cosmic microwave background
The cosmic microwave background (CMB) is the thermal radiation left over from the time of recombination in Big Bang cosmology. In older literature, the CMB is also variously known as cosmic microwave background radiation (CMBR) or ""relic radiation."" The CMB is a cosmic background radiation that is fundamental to observational cosmology because it is the oldest light in the universe, dating to the epoch of recombination. With a traditional optical telescope, the space between stars and galaxies (the background) is completely dark. However, a sufficiently sensitive radio telescope shows a faint background glow, almost exactly the same in all directions, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of CMB in 1964 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and earned the discoverers the 1978 Nobel Prize.The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today.The CMB is well explained as radiation left over from an early stage in the development of the universe, and its discovery is considered a landmark test of the Big Bang model of the universe. When the universe was young, before the formation of stars and planets, it was denser, much hotter, and filled with a uniform glow from a white-hot fog of hydrogen plasma. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled enough, protons and electrons combined to form neutral atoms. These atoms could no longer absorb the thermal radiation, and so the universe became transparent instead of being an opaque fog. Cosmologists refer to the time period when neutral atoms first formed as the recombination epoch, and the event shortly afterwards when photons started to travel freely through space rather than constantly being scattered by electrons and protons in plasma is referred to as photon decoupling. The photons that existed at the time of photon decoupling have been propagating ever since, though growing fainter and less energetic, since the expansion of space causes their wavelength to increase over time (and wavelength is inversely proportional to energy according to Planck's relation). This is the source of the alternative term relic radiation. The surface of last scattering refers to the set of points in space at the right distance from us so that we are now receiving photons originally emitted from those points at the time of photon decoupling.Precise measurements of the CMB are critical to cosmology, since any proposed model of the universe must explain this radiation. The CMB has a thermal black body spectrum at a temperature of 7000272548000000000♠2.72548±0.00057 K. The spectral radiance dEν/dν peaks at 160.2 GHz, in the microwave range of frequencies. (Alternatively if spectral radiance is defined as dEλ/dλ then the peak wavelength is 1.063 mm.) The glow is very nearly uniform in all directions, but the tiny residual variations show a very specific pattern, the same as that expected of a fairly uniformly distributed hot gas that has expanded to the current size of the universe. In particular, the spectral radiance at different angles of observation in the sky contains small anisotropies, or irregularities, which vary with the size of the region examined. They have been measured in detail, and match what would be expected if small thermal variations, generated by quantum fluctuations of matter in a very tiny space, had expanded to the size of the observable universe we see today. This is a very active field of study, with scientists seeking both better data (for example, the Planck spacecraft) and better interpretations of the initial conditions of expansion. Although many different processes might produce the general form of a black body spectrum, no model other than the Big Bang has yet explained the fluctuations. As a result, most cosmologists consider the Big Bang model of the universe to be the best explanation for the CMB.The high degree of uniformity throughout the observable universe and its faint but measured anisotropy lend strong support for the Big Bang model in general and the ΛCDM (""Lambda Cold Dark Matter"") model in particular. Moreover, the fluctuations are coherent on angular scales that are larger than the apparent cosmological horizon at recombination. Either such coherence is acausally fine-tuned, or cosmic inflation occurred.