CONSTRAINTS ON THE VERY HIGH ENERGY
... As large as the IRyO DEBRA uncertainties are, in almost all cases cascading takes less than a few hundred megaparsecs to reprocess an absorbed VHE photon’s energy into that of many photons with individual energies below 11 TeV. This is the primary reason VHE cascading is such a powerful diagnostic: ...
... As large as the IRyO DEBRA uncertainties are, in almost all cases cascading takes less than a few hundred megaparsecs to reprocess an absorbed VHE photon’s energy into that of many photons with individual energies below 11 TeV. This is the primary reason VHE cascading is such a powerful diagnostic: ...
college of science and technology
... signal attenuation and outage than what is experienced in the temperate region. Unfortunately most satellite communication equipments supplied to Africa are designed based on propagation measurements made in Europe and North America, which may not meet the minimum availability standard that can cope ...
... signal attenuation and outage than what is experienced in the temperate region. Unfortunately most satellite communication equipments supplied to Africa are designed based on propagation measurements made in Europe and North America, which may not meet the minimum availability standard that can cope ...
EXERCISES: Set 4 of 4 Q1: (You will need a ruler and a calculator
... solar eclipse of 29 May 1919 confirmed one of the predictions of General Relativity. It was also stated that the first empirical confirmation of strong lensing was the realisation, in 1979, that the two quasars, 0957+561A and 0957+561B are in fact two images of the same object. Does gravitational le ...
... solar eclipse of 29 May 1919 confirmed one of the predictions of General Relativity. It was also stated that the first empirical confirmation of strong lensing was the realisation, in 1979, that the two quasars, 0957+561A and 0957+561B are in fact two images of the same object. Does gravitational le ...
Beyond the Big Bang - Physics Department, Princeton University
... The chosen patch of the sky was a speck, roughly the size of Franklin D. Roosevelt’s eye on a dime if you hold the coin out at arm’s length. The patch appears blank to the human eye and to ground-based telescopes because it contains no stars or galaxies bright enough to be seen. But by adding up th ...
... The chosen patch of the sky was a speck, roughly the size of Franklin D. Roosevelt’s eye on a dime if you hold the coin out at arm’s length. The patch appears blank to the human eye and to ground-based telescopes because it contains no stars or galaxies bright enough to be seen. But by adding up th ...
Dark Energy Probes with DES
... • CCDs : 62 2048 X 4096 pixel CCDs totaling 520 megapixels + 12 2048X2048 CCDs to guide telescope, monitor focus and alignment • The additional crystal depth increases the path length travelled by entering photons. This increases the probability of interaction and allows the CCDs to have an increase ...
... • CCDs : 62 2048 X 4096 pixel CCDs totaling 520 megapixels + 12 2048X2048 CCDs to guide telescope, monitor focus and alignment • The additional crystal depth increases the path length travelled by entering photons. This increases the probability of interaction and allows the CCDs to have an increase ...
Notes-EM
... What are some uses for radiation? X-Rays are used to… • examine luggage and in airports • detect structural problems and cracks in airplanes and bridges •most common use of x-rays is in medicine and ...
... What are some uses for radiation? X-Rays are used to… • examine luggage and in airports • detect structural problems and cracks in airplanes and bridges •most common use of x-rays is in medicine and ...
THE TOPOLOGY OF THE UNIVERSE Is the Universe crumpled?
... space is finite whatever its curvature, even if the matter density and the cosmological constant are very low. Historically, W. de Sitter pointed out in 1917 to Einstein that his static and spherical universe model could put up with a different topology, namely that of projective space. The differen ...
... space is finite whatever its curvature, even if the matter density and the cosmological constant are very low. Historically, W. de Sitter pointed out in 1917 to Einstein that his static and spherical universe model could put up with a different topology, namely that of projective space. The differen ...
Constraining the Topology of the Universe
... circles being compared scales as N 3 , and each comparison takes N 1=2 operations. The simplest implementation of the search at the resolution of the WMAP data (r 9) would take greater than 1022 operations. This is not computationally feasible. However, with the algorithms outlined below, we can ...
... circles being compared scales as N 3 , and each comparison takes N 1=2 operations. The simplest implementation of the search at the resolution of the WMAP data (r 9) would take greater than 1022 operations. This is not computationally feasible. However, with the algorithms outlined below, we can ...
Week 11 notes
... • Highest temperature and lowest density of the three gaseous phases (hot, tenuous phase of the ISM): T ~ 103 to 106 K; n ~ 10-5 to 10-3 atoms/cm3 • Weak degree of concentration to the plane of the Galactic disk: scale height z is a few kpc. Also seen in dense knots known as “HII regions” marking ar ...
... • Highest temperature and lowest density of the three gaseous phases (hot, tenuous phase of the ISM): T ~ 103 to 106 K; n ~ 10-5 to 10-3 atoms/cm3 • Weak degree of concentration to the plane of the Galactic disk: scale height z is a few kpc. Also seen in dense knots known as “HII regions” marking ar ...
Document
... The Hubble Constant – The slope of the line • The Hubble constant is a very fundamental quantity, which tells us the age of the universe. • Today we see that the universe is expanding, and it is growing larger every day. This means that the distance between galaxies are growing in size. • What woul ...
... The Hubble Constant – The slope of the line • The Hubble constant is a very fundamental quantity, which tells us the age of the universe. • Today we see that the universe is expanding, and it is growing larger every day. This means that the distance between galaxies are growing in size. • What woul ...
New layout
... their newest and most luxurious cottage at 1800 square feet with soaring, 20-foot ceilings and spectacular views over the Great Plains. It can sleep up to 8 in comfort. Very tempting! Getting down south by road would be almost a three-day trip and with the price of gas, flying is a possibility. Nov. ...
... their newest and most luxurious cottage at 1800 square feet with soaring, 20-foot ceilings and spectacular views over the Great Plains. It can sleep up to 8 in comfort. Very tempting! Getting down south by road would be almost a three-day trip and with the price of gas, flying is a possibility. Nov. ...
The Universe - Cloudfront.net
... was created and what evidence supports it? Big Bang Theory • All galaxies started from one huge mass of densely packed matter • The densely packed matter exploded with a “big bang” sending out matter and energy in all directions • Over time the matter grouped together to form the stars and galaxies ...
... was created and what evidence supports it? Big Bang Theory • All galaxies started from one huge mass of densely packed matter • The densely packed matter exploded with a “big bang” sending out matter and energy in all directions • Over time the matter grouped together to form the stars and galaxies ...
expert groups - 10sc1-p1-rev
... 3.16 Recognise that as there is more evidence supporting the Big Bang theory than the Steady State theory, it is the currently accepted model for the origin of the Universe 3.17 Describe that if a wave source is moving relative to an observer there will be a change in the observed frequency and wave ...
... 3.16 Recognise that as there is more evidence supporting the Big Bang theory than the Steady State theory, it is the currently accepted model for the origin of the Universe 3.17 Describe that if a wave source is moving relative to an observer there will be a change in the observed frequency and wave ...
ASTR 1020 General Astronomy: Stars and Galaxies REVIEW
... Note: Volume rises as the cube of the mass. Implies the larger the black hole gets, the lower is its density. A sphere of water the size of Saturn’s orbit would be a black hole! ...
... Note: Volume rises as the cube of the mass. Implies the larger the black hole gets, the lower is its density. A sphere of water the size of Saturn’s orbit would be a black hole! ...
Slide 1
... Galaxies cannot travel this fast. Therefore light cannot have been travelling for this length of time. Therefore the Universe must be less than 15 billion years old. The current greatest length of time observed is about 13.5 billion years. ...
... Galaxies cannot travel this fast. Therefore light cannot have been travelling for this length of time. Therefore the Universe must be less than 15 billion years old. The current greatest length of time observed is about 13.5 billion years. ...
Spectroscopic Determination of White Dwarf Candidates for the Dark
... expanding at a decreasing rate until the late 1990's when two independent teams discovered that the expansion of the universe is accelerating. These teams were awarded the Noble Prize in physics in 2012. ...
... expanding at a decreasing rate until the late 1990's when two independent teams discovered that the expansion of the universe is accelerating. These teams were awarded the Noble Prize in physics in 2012. ...
Dark Matter and Dark Energy
... • It is one of the main tasks of LHC experiments to search for any Dark Matter candidates. ...
... • It is one of the main tasks of LHC experiments to search for any Dark Matter candidates. ...
Cosmic future of nuclear and particle physics
... trio) published a theory of creation of elements, which predicted existence of huge number of very soft photons in the Universe. 380,000 years after the Big Bang the temperature of the Universe was above 6000 K and all the atoms were ionized. The large number of charged ions and electrons caused tha ...
... trio) published a theory of creation of elements, which predicted existence of huge number of very soft photons in the Universe. 380,000 years after the Big Bang the temperature of the Universe was above 6000 K and all the atoms were ionized. The large number of charged ions and electrons caused tha ...
feb18_rg
... In the presence of a magnetic field, a dipole tends to align itself with the field. If dipole and field are misaligned, a torque is produced: ...
... In the presence of a magnetic field, a dipole tends to align itself with the field. If dipole and field are misaligned, a torque is produced: ...
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.