In astronomy, dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.
Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter.
The following is a timeline of gravitational physics and general relativity.
An axion is a hypothetical elementary particle originally theorized in 1978 independently by Frank Wilczek and Steven Weinberg as the Goldstone boson of Peccei–Quinn theory, which had been proposed in 1977 to solve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest as a possible component of cold dark matter.
The Fermi Gamma-ray Space Telescope, formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor, is being used to study gamma-ray bursts and solar flares.
In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray with an energy greater than 1 EeV (1018 electronvolts, approximately 0.16 joules), far beyond both the rest mass and energies typical of other cosmic ray particles. The origin of these highest energy cosmic ray is not known.
A strongly interacting massive particle (SIMP) is a hypothetical particle that interacts strongly between themselves and weakly with ordinary matter, but could form the inferred dark matter despite this.
Einstein@Home is a volunteer computing project that searches for signals from spinning neutron stars in data from gravitational-wave detectors, from large radio telescopes, and from a gamma-ray telescope. Neutron stars are detected by their pulsed radio and gamma-ray emission as radio and/or gamma-ray pulsars. They also might be observable as continuous gravitational wave sources if they are rapidly spinning and non-axisymmetrically deformed. The project was officially launched on 19 February 2005 as part of the American Physical Society's contribution to the World Year of Physics 2005 event.
Geminga is a gamma ray and x-ray pulsar source thought to be a neutron star approximately 250 parsecs from the Sun in the constellation Gemini.
The IceCube Neutrino Observatory is a neutrino observatory developed by the University of Wisconsin–Madison and constructed at the Amundsen–Scott South Pole Station in Antarctica. The project is a recognized CERN experiment (RE10). Its thousands of sensors are located under the Antarctic ice, distributed over a cubic kilometer.
An exotic star is a hypothetical compact star composed of exotic matter, and balanced against gravitational collapse by degeneracy pressure or other quantum properties.
Light dark matter, in astronomy and cosmology, are dark matter weakly interacting massive particles (WIMPS) candidates with masses less than 1 GeV. These particles are heavier than warm dark matter and hot dark matter, but are lighter than the traditional forms of cold dark matter, such as Massive Compact Halo Objects (MACHOs). The Lee-Weinberg bound limits the mass of the favored dark matter candidate, WIMPs, that interact via the weak interaction to GeV. This bound arises as follows. The lower the mass of WIMPs is, the lower the annihilation cross section, which is of the order , where m is the WIMP mass and M the mass of the Z-boson. This means that low mass WIMPs, which would be abundantly produced in the early universe, freeze out much earlier and thus at a higher temperature, than higher mass WIMPs. This leads to a higher relic WIMP density. If the mass is lower than GeV the WIMP relic density would overclose the universe.
In cosmology, primordial black holes (PBHs) are hypothetical black holes that formed soon after the Big Bang. In the inflationary era and early radiation-dominated universe, extremely dense pockets of subatomic matter may have been tightly packed to the point of gravitational collapse, creating primordial black holes without the supernova compression typically needed to make black holes today. Because the creation of primordial black holes would pre-date the first stars, they are not limited to the narrow mass range of stellar black holes.
Modern searches for Lorentz violation are scientific studies that look for deviations from Lorentz invariance or symmetry, a set of fundamental frameworks that underpin modern science and fundamental physics in particular. These studies try to determine whether violations or exceptions might exist for well-known physical laws such as special relativity and CPT symmetry, as predicted by some variations of quantum gravity, string theory, and some alternatives to general relativity.
Multi-messenger astronomy is the coordinated observation and interpretation of multiple signals received from the same astronomical event. Many types of cosmological events involve complex interactions between a variety of astrophysical processes, each of which may independently emit signals of a characteristic "messenger" type: electromagnetic radiation, gravitational waves, neutrinos, and cosmic rays. When received on Earth, identifying that disparate observations were generated by the same source can allow for improved reconstruction or a better understanding of the event, and reveals more information about the source.
Daniel Wayne Hooper is an American cosmologist and particle physicist specializing in the areas of dark matter, cosmic rays, and neutrino astrophysics. He is a professor of physics at the University of Wisconsin–Madison and the director of the Wisconsin IceCube Particle Astrophysics Center (WIPAC).
Céline Bœhm is a professor of Particle Physics at the University of Sydney. She works on astroparticle physics and dark matter.
Katelin Schutz is an American particle physicist known for using cosmological observations to study dark sectors, that is new particles and forces that interact weakly with the visible world. She was a NASA Einstein Fellow and Pappalardo Fellow in the MIT Department of Physics and is currently an assistant professor of physics at McGill University.
Indirect detection of dark matter is a method of searching for dark matter that focuses on looking for the products of dark matter interactions rather than the dark matter itself. Contrastingly, direct detection of dark matter looks for interactions of dark matter directly with atoms. There are experiments aiming to produce dark matter particles using colliders. Indirect searches use various methods to detect the expected annihilation cross sections for weakly interacting massive particles (WIMPs). It is generally assumed that dark matter is stable, that dark matter interacts with Standard Model particles, that there is no production of dark matter post-freeze-out, and that the universe is currently matter-dominated, while the early universe was radiation-dominated. Searches for the products of dark matter interactions are profitable because there is an extensive amount of dark matter present in the universe, and presumably, a lot of dark matter interactions and products of those interactions ; and many currently operational telescopes can be used to search for these products. Indirect searches help to constrain the annihilation cross section the lifetime of dark matter , as well as the annihilation rate.
