Gamma-ray burst has highest redshift yet seen
... manifest the collapse of a rapidly spinning massive star—a collapsar—to a black hole about 625 million years after the Big Bang. In fact, GRB090423 is earlier than anything yet observed, at any electromagnetic wavelength, except the cosmic microwave background. No redshift as high as 7 has ever been ...
... manifest the collapse of a rapidly spinning massive star—a collapsar—to a black hole about 625 million years after the Big Bang. In fact, GRB090423 is earlier than anything yet observed, at any electromagnetic wavelength, except the cosmic microwave background. No redshift as high as 7 has ever been ...
ch 15 notes
... The Future of the Universe New observation lead astronomers to believe that the universe will likely expand forever . . . Astronomer, Vera Rubin, discovered that the matter we can see (stars, nebulas, etc.) only makes up about 10% of the mass in galaxies. Most of the matter in space is dark matter, ...
... The Future of the Universe New observation lead astronomers to believe that the universe will likely expand forever . . . Astronomer, Vera Rubin, discovered that the matter we can see (stars, nebulas, etc.) only makes up about 10% of the mass in galaxies. Most of the matter in space is dark matter, ...
Document
... Correlation between black hole mass and velocity dispersion of host stellar system ì = 4:02 æ 0:32; ë ì = 4:02 æ 0:32; ë = 8:13 æ 0:06 Tremaine et al. 2002 ...
... Correlation between black hole mass and velocity dispersion of host stellar system ì = 4:02 æ 0:32; ë ì = 4:02 æ 0:32; ë = 8:13 æ 0:06 Tremaine et al. 2002 ...
radio loudness. - Rencontres de Moriond
... - multiwavelength studies with previously unseen accuracy allow better understanding of jet kinematics, its structure, radiation mechanisms and environments - unified picture of relativistic outflows: quasars, microquasars [Chaty's talk] and gamma-ray bursts (Mirabel 2003; Ghisellini 2003) [De Rujul ...
... - multiwavelength studies with previously unseen accuracy allow better understanding of jet kinematics, its structure, radiation mechanisms and environments - unified picture of relativistic outflows: quasars, microquasars [Chaty's talk] and gamma-ray bursts (Mirabel 2003; Ghisellini 2003) [De Rujul ...
On the Properties and Topology of the Cosmic Web Environments
... The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. 4. Repeat steps 1-3 for a range of filter scales. 5. Combine the environmental signatures of each scale to get a ...
... The NEXUS+ algorithm 1. Apply a filter to the input field. 2. Compute the Hessian of the filtered field f. 3. Use the Hessian eigenvalues to assign an environment signature to each point. 4. Repeat steps 1-3 for a range of filter scales. 5. Combine the environmental signatures of each scale to get a ...
Notes on Photoionized Regions 1. Introduction 2. Hydrogen Nebulae
... The existence of the helium ionization zone also modifies the hydrogen ionization zone. This is for two reasons. One is that photons above 24.6 eV are absorbed by helium and so are not availa ...
... The existence of the helium ionization zone also modifies the hydrogen ionization zone. This is for two reasons. One is that photons above 24.6 eV are absorbed by helium and so are not availa ...
Cosmic Rays and Particle Acceleration - Harvard
... These lecture notes are based off of P. Carlson (2012), Zweibel (2013), Kulsrud, and slides by P. Blasi and others. The derivations for first and second order Fermi acceleration follow High Energy Astrophysics by Longair (3rd ed). This book contains several very nicely written chapters on relativist ...
... These lecture notes are based off of P. Carlson (2012), Zweibel (2013), Kulsrud, and slides by P. Blasi and others. The derivations for first and second order Fermi acceleration follow High Energy Astrophysics by Longair (3rd ed). This book contains several very nicely written chapters on relativist ...
Dark Matter in the Universe
... To answer those questions, researchers compare and contrast observations from specific nearby galaxies. For instance, we learn from the motions of the Magellanic Clouds, two satellite galaxies gloriously visible in the Southern Hemisphere, that they orbit within the Milky Way galaxy’s halo and that ...
... To answer those questions, researchers compare and contrast observations from specific nearby galaxies. For instance, we learn from the motions of the Magellanic Clouds, two satellite galaxies gloriously visible in the Southern Hemisphere, that they orbit within the Milky Way galaxy’s halo and that ...
study of the extensive air shower size and the energy spectra of
... The problem of the altitude dependence of the muon intensity in the 1033 g·cm–2 atmospheric depth is in this respect a specific case to which the present paper is devoted. Cosmic ray particles at very high energies are generated in supernova remnants, on the stars, in Galactic Active Nuclei (AGN), i ...
... The problem of the altitude dependence of the muon intensity in the 1033 g·cm–2 atmospheric depth is in this respect a specific case to which the present paper is devoted. Cosmic ray particles at very high energies are generated in supernova remnants, on the stars, in Galactic Active Nuclei (AGN), i ...
Media Release
... universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos. Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists ha ...
... universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos. Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists ha ...
Dark Matter
... The concept of gravity is that anything with mass-produces a force on any thing around it, an attraction if you will. And the larger an object, the larger the gravitational forces are. Now apply these basic principles to the universe, and everything makes sense. Asteroids are drawn towards the gravi ...
... The concept of gravity is that anything with mass-produces a force on any thing around it, an attraction if you will. And the larger an object, the larger the gravitational forces are. Now apply these basic principles to the universe, and everything makes sense. Asteroids are drawn towards the gravi ...
Thermal history of the universe with dark energy
... supernovae [5, 6] showed that the universe was expanding at an accelerated rate, which justified the introduction of an entity with negative pressure to account for it, the dark energy. This revived the cosmological constant in a different context, now bearing responsibility for the accelerated expa ...
... supernovae [5, 6] showed that the universe was expanding at an accelerated rate, which justified the introduction of an entity with negative pressure to account for it, the dark energy. This revived the cosmological constant in a different context, now bearing responsibility for the accelerated expa ...
Spectra of Cosmic Ray Protons and Helium Produced in Supernova
... To demonstrate a possible effect of acceleration by reverse shocks on cosmic-ray composition, we make calculations for two classes of supernovae: Type I where Hydrogen is absent in the outer layers of ejecta and Type II where Hydrogen strongly prevails. The relative rates of these types of supernova ...
... To demonstrate a possible effect of acceleration by reverse shocks on cosmic-ray composition, we make calculations for two classes of supernovae: Type I where Hydrogen is absent in the outer layers of ejecta and Type II where Hydrogen strongly prevails. The relative rates of these types of supernova ...
Cosmic Extremes
... some energy to this radiation. As a result, physicists do not expect to see many cosmic rays above a certain energy, provided that their sources are very far away. This energy is called the GZK cutoff, after the physicists who first predicted it in 1966: Kenneth Greisen, Georgi Zatsepin, and Vadim K ...
... some energy to this radiation. As a result, physicists do not expect to see many cosmic rays above a certain energy, provided that their sources are very far away. This energy is called the GZK cutoff, after the physicists who first predicted it in 1966: Kenneth Greisen, Georgi Zatsepin, and Vadim K ...
Dark Matter in the Universe
... To answer those questions, researchers compare and contrast observations from specific nearby galaxies. For instance, we learn from the motions of the Magellanic Clouds, two satellite galaxies gloriously visible in the Southern Hemisphere, that they orbit within the Milky Way galaxy’s halo and that ...
... To answer those questions, researchers compare and contrast observations from specific nearby galaxies. For instance, we learn from the motions of the Magellanic Clouds, two satellite galaxies gloriously visible in the Southern Hemisphere, that they orbit within the Milky Way galaxy’s halo and that ...
17.1 Introduction
... of convection, which then prevents the helium ionization zone from driving the pulsation. For hotter temperatures, the helium ionization zone is located too far out in the atmosphere for significant pulsations to occur. There are complications, of course. Stars spend only a short fraction of their l ...
... of convection, which then prevents the helium ionization zone from driving the pulsation. For hotter temperatures, the helium ionization zone is located too far out in the atmosphere for significant pulsations to occur. There are complications, of course. Stars spend only a short fraction of their l ...
Cosmic Hide and Seek: the Search for the Missing Mass
... In 1933, the astronomer Fritz Zwicky was studying the motions of distant galaxies. Zwicky estimated the total mass of a group of galaxies by measuring their brightness. When he used a different method to compute the mass of the same cluster of galaxies, he came up with a number that was 400 times hi ...
... In 1933, the astronomer Fritz Zwicky was studying the motions of distant galaxies. Zwicky estimated the total mass of a group of galaxies by measuring their brightness. When he used a different method to compute the mass of the same cluster of galaxies, he came up with a number that was 400 times hi ...
MORSELLI * Dark Matter Signals in the gamma
... show that gauge invariance implies interesting constraints from associated cosmic ray emission (upper bounds on these lines). ...
... show that gauge invariance implies interesting constraints from associated cosmic ray emission (upper bounds on these lines). ...
6 Big Bang Nucleosynthesis - Course Pages of Physics Department
... Thus µe /T ∼ η ∼ 10−9 . The nonrelativistic limit can be done in a similar manner. It turns out that µe rises as T falls, and somewhere between T = 30 keV and T = 10 keV µe becomes larger than T , and, in fact, comparable to me . For T & 30 keV, µe ≪ T , and we can drop the µe in Eq. (11). Since we ...
... Thus µe /T ∼ η ∼ 10−9 . The nonrelativistic limit can be done in a similar manner. It turns out that µe rises as T falls, and somewhere between T = 30 keV and T = 10 keV µe becomes larger than T , and, in fact, comparable to me . For T & 30 keV, µe ≪ T , and we can drop the µe in Eq. (11). Since we ...
(S. Lloyd 2001) - Digilander
... Here, these three limits are applied to calculate the information processing capacity ...
... Here, these three limits are applied to calculate the information processing capacity ...
English - Wise Observatory
... enhanced gravity force. The gravity “holes” are provided by dark matter, which makes up 23% of the Universe while the luminous matter is only a few percent. Although the nature of the dark matter is sill unknown, theoretical simulations indicated that the Universe is peppered by dark matter concentr ...
... enhanced gravity force. The gravity “holes” are provided by dark matter, which makes up 23% of the Universe while the luminous matter is only a few percent. Although the nature of the dark matter is sill unknown, theoretical simulations indicated that the Universe is peppered by dark matter concentr ...
Sunyaev±Zel'dovich distortion from early galactic winds Subhabrata Majumdar, Biman B. Nath
... We assume, as in TSE, that the total mechanical luminosity of the outflow is Lsn , 1:2 M b =M( L( ; where Mb is the baryonic mass of the parent galaxy. Since the galactic winds last for tburn , 5 107 yr; the total energy in the galactic wind is 0:02 0:007 M b c2 ; where Mb is the baryonic ma ...
... We assume, as in TSE, that the total mechanical luminosity of the outflow is Lsn , 1:2 M b =M( L( ; where Mb is the baryonic mass of the parent galaxy. Since the galactic winds last for tburn , 5 107 yr; the total energy in the galactic wind is 0:02 0:007 M b c2 ; where Mb is the baryonic ma ...
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.