Extractions: Dark Matter in the Universe The Electronic Universe Project (University of Oregon) For every gram of matter in the universe that shines or radiates energy, there are between 10 and 100 grams of matter that give off no light at all. This mysterious "dark matter" is not made up of atoms or molecules - scientists can only theorize and speculate about its nature. But the gravitational effects of dark matter are indisputable - they affect all the motion and evolution of the largest structures in the universe, including galaxies, clusters, and superclusters. This movie shows how dark matter moves and distributes itself to make certain kinds of galaxies. Dark matter, galaxy types, and structure development There is a rather wide range of different galaxy types, shapes and densities, which means the process of forming galaxies is very complex. Also most all galaxies today are embedded in some larger scale structure, although the formation of these structures is unclear. Structure formation could have either occurred from fragmentation of very large regions into smaller regions, or from the gravitational attraction of small pieces into successively large structures. Both formation scenarios lead to a highly clustered universe with structure on many different size scales. This particular movie, a time-lapse presentation of a supercomputer calculation, shows how an evenly distributed amount of dark matter, given time, will form structures such as elliptical blobs, webs and filaments, purely from the force of gravity.
Extractions: Dark Matter: Strong Gravitational Lensing Tony Tyson and Ayana Holloway (Lucent Technologies' Bell Labs) According to the General Theory of Relativity, mass warps space-time (this is what causes gravity). When light travels through space, then, its path is bent if it passes near large concentrations of matter. Thus, massive objects in the universe can act like huge magnifying glasses, distorting and concentrating light traveling around and through them. This effect is called gravitational lensing. This movie shows how it might work in a cluster of hundreds of galaxies. Strong Gravitational Lensing When light rays from a distant source bend around both sides of a massive object and cross near Earth, the effect is called "strong gravitational lensing." Strong lensing magnifies and distorts light from the source, and in some cases also produces multiple images of the source. This movie shows a simulation of strong lensing by a massive cluster of galaxies containing huge amounts of both visible matter and "dark matter." The light distortion effects are exaggerated in the movie, but generally speaking such effects are common since rich clusters of galaxies are the largest concentrations of matter in the universe. In fact, the patterns of distortion help astronomers determine the amount of dark matter in clusters, and how that matter is spread in the cluster - both of which tell a great deal about the behavior of matter in the cosmos as a whole.
CFHT Gives First Glimpse Of Dark Matter Distribution The cosmic distribution of this dark matter is difficult to study since astronomical 1 Canadian Institute for Theoretical Astrophysics, Toronto, Canada http://www.cfht.hawaii.edu/News/Lensing/
Extractions: An international team of astronomers based in France has obtained the first-ever glimpse of the distribution of dark matter over a large section of sky. The team used images from the Canada-France-Hawaii Telescope's high-resolution wide-field imaging camera to analyze the light of 200,000 distant galaxies, looking for distortions caused by intervening dark matter. The results give cosmologists their first clear window into the possible roles of dark matter in the evolution of the Universe. The 13-member team, headed by Dr. Yannick Mellier of the Institut d'Astrophysique de Paris and the Observatoire de Paris, drew on a wide range of expertise, including cosmology, astrophysics, statistics, data analysis and instrument technology by bringing together researchers from France, Germany, Canada and the United States. The nature of dark matter is one of the greatest unsolved mysteries of modern science. While dark matter makes up at least 90% of the mass of the Universe, both its composition and its distribution are unknown. Knowledge of dark matter is, however, critical to understanding the evolution and fate of the Universe.
Inquiring Minds The particle physics and astrophysics communities share the need for new measurements, Fermilab physicists search for dark matter directly through the http://www.fnal.gov/pub/inquiring/physics/astrophysics/
Extractions: Fermilab is recognized worldwide as a laboratory where advances in particle physics, astrophysics and cosmology converge. The experimental results and theoretical predictions of accelerator-based particle physics experiments shed light on the birth and evolution of the universe immediately after the Big Bang. Similarly, advances in the understanding of the large-scale structure and evolution of the universe give new insight into the nature of matter at the smallest scale. Results from recent particle physics research and its theoretical interpretations guide astrophysical thought in new directions. At the same time, astrophysical observations and computations have provided evidence for such phenomena as dark matter, invisible mass that cannot be accounted for by elementary particles thus far identified in laboratory experiments, and dark energy, a mysterious force that is driving the universe apart. The particle physics and astrophysics communities share the need for new measurements, new mathematical approaches and powerful computers for simulations. Fermilab's 50 theoretical and experimental astrophysicists are actively involved in several astrophysical projects, with research focused on understanding the nature of dark matter and dark energy. These projects will also shed light on the mass of neutrinos and on inflation, the mechanism believed to be responsible for structure in the universe.
Inquiring Minds Many speculations exist about the origin and composition of dark matter.The Cryogenic dark matter Search (CDMS) experiment is looking for dark matter in http://www.fnal.gov/pub/inquiring/physics/astrophysics/colddarkmatter.html
Extractions: Based on thorough observations of the sky, astrophysicists noticed years ago that the shape and motion of galaxies and other objects cannot be explained with visible matter, the matter we know from stars and planets. The data suggested gravitional forces that can only be explained by what physicists called dark matter. Many speculations exist about the origin and composition of dark matter. The Cryogenic Dark Matter Search (CDMS) experiment is looking for dark matter in the form of Weakly Interacting Massive Particles, or WIMPs. One attempt to solve the dark matter problem hypothesizes the existance of an undiscovered particle already existed in the very early universe. One can calculate the abundance of these particles in the universe today. If these particles are to provide the mass necessary to prevent the universe from expanding for ever, their interaction with other matter must be very weak and their mass should be in the range 10 GeV to 10,000 GeV. (For comparison: the mass of a proton equals 1 GeV.) These properties gave rise to the name WIMP. Gravitational forces should keep WIMPs within our galaxy. We can imagine a cloud of WIMPs clumped around our galaxy, with the solar system sweeping through this cloud as we orbit the center of the Milky Way. WIMPs could easily travel through regular matter, like the earth, and the particles should have a mean velocity relative to the earth of about 300 km/s.
Extractions: We review some recent determinations of the amount of dark matter on galactic, cluster, and large scales, noting some puzzles and their possible resolutions. We discuss the interpretation of big bang nucleosynthesis for dark matter, and then review the motivation for and basic physics of several dark matter candidates, including Machos, Wimps, axions, and neutrinos. Finally, we discuss how the uncertainty in the models of the Milky Way dark halo will affect the dark matter detection experiments. References and citations for this submission:
SPACE.com -- Astrophysics Challenged By Dark Energy Finding Astrophysics Challenged By dark Energy Finding By Ray Villard In the case ofdark energy the simpler explanation is that dark matter http://www.space.com/scienceastronomy/generalscience/darkenergy_folo_010410.html
Center For Space Science And Astrophysics: Courses What is the cosmic dark matter? Can we predict the future evolution of the cosmos? Introduction to Extragalactic Astrophysics and Cosmology http://www.stanford.edu/group/CSSA/courses.html
Extractions: Although Stanford University does not have a degree program in astronomy or astrophysics, teaching and research in various branches of these disciplines is an ongoing activity in the departments of Applied Physics, Electrical Engineering, and Physics. For the convenience of students interested in the general areas of astronomy, astrophysics, and cosmology, a course program for undergraduate and graduate study is listed below. The program is especially committed to providing introductory courses for the student who wishes to be informed about the fields of astronomy without the need for prerequisites beyond high school algebra and physics. Astronomy courses numbered below 100 are designed to serve this group of students. Astronomy courses numbered 100-199 serve the student interested in an initial scientific study of astronomy. The courses numbered 200 and above are for graduate students and advanced undergraduates, subject to prior approval by the course instructor. PHYSICS 15A. The Nature of the Universe Introduction to the structure, origin, and evolution of the universe. The objects which make up the universe: galaxies, stars, planets, etc. Enigmas of modern astronomy: dark matter, quasars, x-ray sources, black holes, and pulsars. Topics: the formation of the sun and planets; the formation and evolution of stars and the dynamics and evolution of our galaxy; the organization and dynamics of luminous and nonluminous matter in the universe; the creation, evolution, and ultimate fate of the universe; and the search for life beyond our solar system. GER:2a (DR:5) 3 units
Stanford University Astronomy Program The Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) Focusing on Cryogenic dark matter Search (CDMS) Directdetection search for weakly http://www.stanford.edu/dept/astro/
Extractions: Although Stanford University does not have a degree program in Astronomy or Space Science, teaching and research in various branches of these disciplines is an ongoing activity in the Departments of Physics Aeronautics and Astronautics Applied Physics , and Electrical Engineering , as well as at the W.W. Hansen Experimental Physics Laboratory (HEPL) and the Stanford Linear Accelerator Center (SLAC) . Bridging the research efforts on the Stanford campus and at SLAC, as well as between theoretical and experimental physics communities, is the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC)
Theoretical Astrophysics And Cosmology We also have close ties to the Fermilab Theoretical Astrophysics Group, Current research topics include the nature of dark matter and dark energy, http://physics.uchicago.edu/t_astro.html
Extractions: Physics Home ON THIS PAGE: Sean M. Carroll Eugene N. Parker Robert Rosner Michael S. Turner The University of Chicago is a leader in interdisciplinary research in theoretical astrophysics and cosmology, including connections to particle physics, general relativity, and computational physics. Collaboration with the Department of Astronomy and Astrophysics is organized under the Enrico Fermi Institute . The NSF-funded Center for Cosmological Physics organizes research, symposia, a visitors program, and education/outreach activities at the interface of phyiscs and astrophysics. We also have close ties to the Fermilab Theoretical Astrophysics Group , which focuses on both early- and late-universe cosmology, and the ASCI Flash Center at Chicago, which carries out numerical studies of astrophysical thermonuclear flashes. Current research topics include the nature of dark matter and dark energy, inflationary cosmology, plasma physics and magnetohydrodynamics, solar and stellar astrophysics, large-scale structure, the cosmic microwave background, and connections to string theory and quantum gravity. Sean M. Carroll
CDMS Publications B. Sadoulet, dark matter, A Challenge for Particle Astrophysics, to appear inproceedings of the NATO Advanced Study Institute on Frontiers of Particle http://cosmology.berkeley.edu/preprints/cdms/cdms.html
Extractions: (listed in reverse chronological order) D.S. Akerib et al., Limits on spin-dependent WIMP-nucleon interactions from the Cryogenic Dark Matter Search , submitted to PRL, astro-ph/0509269 D.S. Akerib et al., Limits on spin-independent WIMP-nucleon interactions from the two-tower run of the Cryogenic Dark Matter Search , submitted to PRL, astro-ph/0509259 D.S. Akerib et al., Exclusion Limits on the WIMP-Nucleon Cross-Section from the First Run of the Cryogenic Dark Matter Search in the Soudan Underground Lab , to appear in PRD, astro-ph/0507190 (listed in reverse chronological order) D.S. Akerib et al., First Results from the Cryogenic Dark Matter Search in the Soudan Underground Lab , Phys. Rev. Lett. astro-ph/0405033 P.L. Brink et al., Further results from the CDMS experiment , LTD-10, 10th International Workshop on Low Temperature Detectors, Genoa, Italy 7-11 July 2003; NIM A 520 (2004) 105-107. (pdf) C.L. Chang et al., Installation and commissioning of the CDMSII experiment at Soudan , LTD-10, 10th International Workshop on Low Temperature Detectors, Genoa, Italy 7-11 July 2003; NIM A 520 (2004) 116-119.
Astrophysics | Dark Messengers | Economist.com Astrophysics dark messengers. Mar 17th 2005 dark matter is perceived throughits gravitational pull on the more familiar normal matter of stars and http://www.economist.com/science/displaystory.cfm?story_id=3764508
Cosmology | Things Fall Apart | Economist.com What if the dark energy and dark matter essential to modern explanations of the and colleagues published their findings in Astronomy and Astrophysics. http://www.economist.com/science/displayStory.cfm?story_id=2404626
ASTROPHYSICS: ON THE NATURE OF DARK MATTER ASTROPHYSICS dark matter AND dark ENERGY The following points are made by SeanCarroll (Nature 2004 42927) 1) Humans seem to be extremely unimportant in http://scienceweek.com/2004/sc041224-1.htm
Extractions: 1) Astrophysical observations reveal that galaxies and clusters of galaxies are gravitationally held together by vast halos of dark (i.e., nonluminous) matter. Theoretical reasoning points to two leading candidates for the particles that may make up this mysterious form of matter: weakly interacting massive particles (WIMPs) and theoretical particles called "axions". Particle accelerators have not yet detected either of the two particles, but recent astrophysical observations provide hints that both particles may exist in the Universe, although definitive data are still lacking. Dark matter need not consist exclusively of only one of these two types of particles. 2) Precise measurements of the cosmic microwave background have shown that dark matter makes up about 25% of the energy budget of the Universe; visible matter in the form of stars, gas, and dust only contributes about 4%. However, the nature of dark matter remains a mystery. To explain it, we must go beyond the standard model of elementary particles and look toward more exotic types of particles.
Encyclopedia Of Astronomy And Astrophysics » Dark Matter: Its Nature dark matter Its Nature. Author. Georg G Raffelt one of the greatest unsolvedmysteries of astrophysics, cosmology, and elementary particle physics. http://eaa.iop.org/index.cfm?action=summary&doc=eaa/2105@eaa-xml
Sheffield Particle Astrophysics: Dark Matter The search for dark matter Particle astrophysics projects throughout Europeare now coordinated by an EU Framework 6 programme known as ILIAS http://www.shef.ac.uk/physics/research/pppa/research/dmintro.htm
Extractions: This page under construction - please check again later! Many lines of astrophysical and cosmological evidence indicate that the bulk of the matter in the Universe is composed of some as yet undiscovered weakly interacting particle. The favoured candidate is the Weakly Interacting Massive Particle (WIMP) predicted by various extensions to the Standard Model of particle physics, particularly supersymmetry. Sheffield manages the UK's only deep underground physics laboratory, at Boulby Mine north of Whitby, and is a key participant in the UK Dark Matter Collaboration, one of the world's leading WIMP search groups. The work of the group includes designing and constructing state-of-the art detectors, as well as analysing data from existing experiments. Particle astrophysics projects throughout Europe are now coordinated by an EU Framework 6 programme known as ILIAS (Integrated Large Infrastructures for Astroparticle Science). Sheffield plays a role in several ILIAS activities, including transnational access to deep underground science laboratories - this includes Boulby Mine as well as centres in Italy (Gran Sasso), Spain (Canfranc) and France (Frejus);
Particle Astrophysics Seminars « Events Particle/Astrophysics Seminars, Spring 2005 Abstract The only evidence sofar for the presence of dark matter in our Galaxy is through its http://www.phys.cwru.edu/events/pa.php?abstract=7
Astrophysics And Cosmology At Florida State University What is dark matter? and What is the nature of dark Energy? Nuclear Astrophysicsis the research field which explains the origin of the elements and the http://www.physics.fsu.edu/research/Astrophysics/AstroPhysics.html
Extractions: What is dark matter? What is the nature of dark energy? How were the elements from iron to uranium made? Are there new states of matter at exceedingly high density and temperature? The Physics Department at Florida State University is making significant contributions in all these areas which depend on the synergism between scientific disciplines as diverse as earth and space-based observations, terrestrial experiments, theoretical modeling, and computer simulations. The cosmic microwave background is the afterglow radiation left over from the hot Big Bang. Its temperature is extremely uniform all over the sky. However, tiny temperature variations or fluctuations (at the part per million level) can offer great insight into the origin, evolution, and content of the universe. A variety of astrophysical measurements [galactic rotation curves, galactic binding, mappings of the cosmic microwave background radiation (CMB)] all point to the fact that nuclear matter only comprises a tiny fraction of the total matter and energy density of the universe. In addition to nuclear matter, there is also a pervasive dark energy component responsible for the apparent accelerating expansion of the universe, and a cold dark matter (CDM) component, which is responsible for large scale structure formation in the universe.
NYU Physics Astrophysics And Relativity Seminars Dust grains play a variety of critical roles in astrophysics. On a superficiallevel, Investigating the Origins of dark matter Halo Density Profiles http://www.physics.nyu.edu/cgi-bin/astro
Extractions: University of Washington Understanding the Assembly of Disk and Bulges in a Cold Dark Matter Universe I will present results from a new set of multi million particle simulations of the formation of individual disk galaxies in a cosmological context. I will show how improved resolution and a physically motivated description of energy feedback allow the formation of galaxies with realistic disks and the correct abundance of satellites. Feedback significantly delays star formation in smaller galaxies, easily reproducing the observed anti-hierarchical trend in the age-mass relation.
