Dark matter

For other uses, see Dark Matter (disambiguation).Not to be confused with Antimatter or Dark energy.

Unsolved problem in physics:

What is dark matter? How was it generated?

(more unsolved problems in physics)

In astronomy, dark matter is an invisible and 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, ^[1] gravitational lensing, ^[2] the observable universe's current structure, mass position in galactic collisions, ^[3] the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.

In the standard Lambda-CDM model of cosmology, the mass–energy content of the universe is 5% ordinary matter, 26.8% dark matter, and 68.2% a form of energy known as dark energy. ^{[4] [5] [6] [7]} Thus, dark matter constitutes 85% of the total mass, while dark energy and dark matter constitute 95% of the total mass–energy content. ^{[8] [9] [10] [11]}

Dark matter is not known to interact with ordinary baryonic matter and radiation except through gravity, making it difficult to detect in the laboratory. The most prevalent explanation is that dark matter is some as-yet-undiscovered subatomic particle, such as either weakly interacting massive particles (WIMPs) or axions. ^[12] The other main possibility is that dark matter is composed of primordial black holes. ^{[13] [14] [15]}

Dark matter is classified as "cold", "warm", or "hot" according to velocity (more precisely, its free streaming length). Recent models have favored a cold dark matter scenario, in which structures emerge by the gradual accumulation of particles.

Although the astrophysics community generally accepts the existence of dark matter, ^[16] a minority of astrophysicists, intrigued by specific observations that are not well explained by ordinary dark matter, argue for various modifications of the standard laws of general relativity. These include modified Newtonian dynamics, tensor–vector–scalar gravity, or entropic gravity. So far none of the proposed modified gravity theories can describe every piece of observational evidence at the same time, suggesting that even if gravity has to be modified, some form of dark matter will still be required. ^[17]

History

Early history

The hypothesis of dark matter has an elaborate history. ^{[18] [19]} Wm. Thomson, Lord Kelvin, discussed the potential number of stars around the Sun in the appendices of a book based on a series of lectures given in 1884 in Baltimore. ^{[20] [18]} He inferred their density using the observed velocity dispersion of the stars near the Sun, assuming that the Sun was 20–100 million years old. He posed what would happen if there were a thousand million stars within 1  kiloparsec of the Sun (at which distance their parallax would be 1  milli-arcsecond). Kelvin concluded

Many of our supposed thousand million stars – perhaps a great majority of them – may be dark bodies. ^{[20] [21]}

In 1906, Poincaré ^[22] used the French term [matière obscure] ("dark matter") in discussing Kelvin's work. ^{[22] [21]} He found that the amount of dark matter would need to be less than that of visible matter, incorrectly, it turns out. ^{[21] [18]}

The second to suggest the existence of dark matter using stellar velocities was Dutch astronomer Jacobus Kapteyn in 1922. ^{[23] [24]}

A publication from 1930 by Swedish astronomer Knut Lundmark points to him being the first to realise that the universe must contain much more mass than can be observed. ^[25] Dutch radio astronomy pioneer Jan Oort also hypothesized the existence of dark matter in 1932. ^{[24] [26] [27]} Oort was studying stellar motions in the galactic neighborhood and found the mass in the galactic plane must be greater than what was observed, but this measurement was later determined to be incorrect. ^[28]

In 1933, Swiss astrophysicist Fritz Zwicky studied galaxy clusters while working at Cal Tech and made a similar inference. ^{[29] [a] [30]} Zwicky applied the virial theorem to the Coma Cluster and obtained evidence of unseen mass he called dunkle Materie ('dark matter'). Zwicky estimated its mass based on the motions of galaxies near its edge and compared that to an estimate based on its brightness and number of galaxies. He estimated the cluster had about 400 times more mass than was visually observable. The gravity effect of the visible galaxies was far too small for such fast orbits, thus mass must be hidden from view. Based on these conclusions, Zwicky inferred some unseen matter provided the mass and associated gravitational attraction to hold the cluster together. ^[31] Zwicky's estimates were off by more than an order of magnitude, mainly due to an obsolete value of the Hubble constant; ^[32] the same calculation today shows a smaller fraction, using greater values for luminous mass. Nonetheless, Zwicky did correctly conclude from his calculation that most of the gravitational matter present was dark. ^[21] However unlike modern theories, Zwicky considered "dark matter" to be non-luminous ordinary matter. ^{[18] : III.A}

Further indications of mass-to-light ratio anomalies came from measurements of galaxy rotation curves. In 1939, H.W. Babcock reported the rotation curve for the Andromeda nebula (now called the Andromeda Galaxy), which suggested the mass-to-luminosity ratio increases radially. ^[33] He attributed it to either light absorption within the galaxy or modified dynamics in the outer portions of the spiral, rather than to unseen matter. Following Babcock's 1939 report of unexpectedly rapid rotation in the outskirts of the Andromeda Galaxy and a mass-to-light ratio of 50; in 1940, Oort discovered and wrote about the large non-visible halo of NGC 3115. ^[34]

1970s

The hypothesis of dark matter largely took root in the 1970s. Several different observations were synthesized to argue that galaxies should be surrounded by halos of unseen matter. In two papers that appeared in 1974, this conclusion was drawn in tandem by independent groups: in Princeton, New Jersey, by Jeremiah Ostriker, Jim Peebles, and Amos Yahil, and in Tartu, Estonia, by Jaan Einasto, Enn Saar, and Ants Kaasik. ^[35]

One of the observations that served as evidence for the existence of galactic halos of dark matter was the shape of galaxy rotation curves. These observations were done in optical and radio astronomy. In optical astronomy, Vera Rubin and Kent Ford worked with a new spectrograph to measure the velocity curve of edge-on spiral galaxies with greater accuracy. ^{[36] [37] [38]}

At the same time, radio astronomers were making use of new radio telescopes to map the 21 cm line of atomic hydrogen in nearby galaxies. The radial distribution of interstellar atomic hydrogen (H^I) often extends to much greater galactic distances than can be observed as collective starlight, expanding the sampled distances for rotation curves – and thus of the total mass distribution – to a new dynamical regime. Early mapping of Andromeda with the 300-foot (91 m) telescope at Green Bank ^[39] and the 250-foot (76 m) dish at Jodrell Bank ^[40] already showed the H^I rotation curve did not trace the decline expected from Keplerian orbits.

As more sensitive receivers became available, Roberts & Whitehurst (1975) ^[41] were able to trace the rotational velocity of Andromeda to 30 kpc, much beyond the optical measurements. Illustrating the advantage of tracing the gas disk at large radii; that paper's Figure 16 ^[41] combines the optical data ^[38] (the cluster of points at radii of less than 15 kpc with a single point further out) with the H^I data between 20 and 30 kpc, exhibiting the flatness of the outer galaxy rotation curve; the solid curve peaking at the center is the optical surface density, while the other curve shows the cumulative mass, still rising linearly at the outermost measurement. In parallel, the use of interferometric arrays for extragalactic H^I spectroscopy was being developed. Rogstad & Shostak (1972) ^[42] published H^I rotation curves of five spirals mapped with the Owens Valley interferometer; the rotation curves of all five were very flat, suggesting very large values of mass-to-light ratio in the outer parts of their extended H^I disks. ^[42] In 1978, Albert Bosma showed further evidence of flat rotation curves using data from the Westerbork Synthesis Radio Telescope. ^[43]

By the late 1970s the existence of dark matter halos around galaxies was widely recognized as real, and became a major unsolved problem in astronomy. ^[35]

1980–1990s

A stream of observations in the 1980–1990s supported the presence of dark matter. Persic, Salucci & Stel (1996) is notable for the investigation of 967 spirals. ^[44] The evidence for dark matter also included gravitational lensing of background objects by galaxy clusters, ^{[45] (pp 14–16)} the temperature distribution of hot gas in galaxies and clusters, and the pattern of anisotropies in the cosmic microwave background.

According to the current consensus among cosmologists, dark matter is composed primarily of some type of not-yet-characterized subatomic particle. ^{[46] [47]} The search for this particle, by a variety of means, is one of the major efforts in particle physics. ^[48]

Technical definition

See also: Friedmann equations

In standard cosmological calculations, "matter" means any constituent of the universe whose energy density scales with the inverse cube of the scale factor, i.e., ρ ∝ a⁻³. This is in contrast to "radiation", which scales as the inverse fourth power of the scale factor ρ ∝ a⁻⁴, and a cosmological constant, which does not change with respect to a (ρ ∝ a⁰). ^[49] The different scaling factors for matter and radiation are a consequence of radiation redshift. For example, after doubling the diameter of the observable Universe via cosmic expansion, the scale, a, has doubled. The energy of the cosmic microwave background radiation has been halved (because the wavelength of each photon has doubled); ^[50] the energy of ultra-relativistic particles, such as early-era standard-model neutrinos, is similarly halved. ^[b] The cosmological constant, as an intrinsic property of space, has a constant energy density regardless of the volume under consideration. ^[49]

In principle, "dark matter" means all components of the universe which are not visible but still obey ρ ∝ a⁻³. In practice, the term "dark matter" is often used to mean only the non-baryonic component of dark matter, i.e., excluding "missing baryons". ^[51] Context will usually indicate which meaning is intended.

Observational evidence

Galaxy rotation curves

Main article: Galaxy rotation curve

Animation of rotating disc galaxies. Dark matter –shown in red –is more concentrated near the center and it rotates more rapidly.

The arms of spiral galaxies rotate around their galactic center. The luminous mass density of a spiral galaxy decreases as one goes from the center to the outskirts. If luminous mass were all the matter, then the galaxy can be modelled as a point mass in the centre and test masses orbiting around it, similar to the Solar System. ^[c] From Kepler's Third Law, it is expected that the rotation velocities will decrease with distance from the center, similar to the Solar System. This is not observed. ^[52] Instead, the galaxy rotation curve remains flat or even increases as distance from the center increases.

If Kepler's laws are correct, then the obvious way to resolve this discrepancy is to conclude the mass distribution in spiral galaxies is not similar to that of the Solar System. In particular, there may be a lot of non-luminous matter (dark matter) in the outskirts of the galaxy.

Velocity dispersions

Main article: Velocity dispersion

Stars in bound systems must obey the virial theorem. The theorem, together with the measured velocity distribution, can be used to measure the mass distribution in a bound system, such as elliptical galaxies or globular clusters. With some exceptions, velocity dispersion estimates of elliptical galaxies ^[53] do not match the predicted velocity dispersion from the observed mass distribution, even assuming complicated distributions of stellar orbits. ^[54]

As with galaxy rotation curves, the obvious way to resolve the discrepancy is to postulate the existence of non-luminous matter.

Galaxy clusters

Galaxy clusters are particularly important for dark matter studies since their masses can be estimated in three independent ways:

• From the scatter in radial velocities of the galaxies within clusters
• From X-rays emitted by hot gas in the clusters. From the X-ray energy spectrum and flux, the gas temperature and density can be estimated, hence giving the pressure; assuming pressure and gravity balance determines the cluster's mass profile.
• Gravitational lensing (usually of more distant galaxies) can measure cluster masses without relying on observations of dynamics (e.g., velocity).

Generally, these three methods are in reasonable agreement that dark matter outweighs visible matter by approximately 5 to 1. ^[55]

Gravitational lensing

One of the consequences of general relativity is the gravitational lens. Gravitational lensing occurs when massive objects between a source of light and the observer act as a lens to bend light from this source. Lensing does not depend on the properties of the mass; it only requires there to be a mass. The more massive an object, the more lensing is observed. An example is a cluster of galaxies lying between a more distant source such as a quasar and an observer. In this case, the galaxy cluster will lens the quasar.

Strong lensing is the observed distortion of background galaxies into arcs when their light passes through such a gravitational lens. It has been observed around many distant clusters including Abell 1689. ^[56] By measuring the distortion geometry, the mass of the intervening cluster can be obtained. In the weak regime, lensing does not distort background galaxies into arcs, causing minute distortions instead. By examining the apparent shear deformation of the adjacent background galaxies, the mean distribution of dark matter can be characterized. The measured mass-to-light ratios correspond to dark matter densities predicted by other large-scale structure measurements. ^{[57] [58]}

Cosmic microwave background

Main article: Cosmic microwave background

Although both dark matter and ordinary matter are matter, they do not behave in the same way. In particular, in the early universe, ordinary matter was ionized and interacted strongly with radiation via Thomson scattering. Dark matter does not interact directly with radiation, but it does affect the cosmic microwave background (CMB) by its gravitational potential (mainly on large scales) and by its effects on the density and velocity of ordinary matter. Ordinary and dark matter perturbations, therefore, evolve differently with time and leave different imprints on the CMB.

The CMB is very close to a perfect blackbody but contains very small temperature anisotropies of a few parts in 100,000. A sky map of anisotropies can be decomposed into an angular power spectrum, which is observed to contain a series of acoustic peaks at near-equal spacing but different heights. The locations of these peaks depend on cosmological parameters. Matching theory to data, therefore, constrains cosmological parameters. ^[59]

The CMB anisotropy was first discovered by COBE in 1992, though this had too coarse resolution to detect the acoustic peaks. After the discovery of the first acoustic peak by the balloon-borne BOOMERanG experiment in 2000, the power spectrum was precisely observed by WMAP in 2003–2012, and even more precisely by the Planck spacecraft in 2013–2015. The results support the Lambda-CDM model. ^{[60] [61]}

The observed CMB angular power spectrum provides powerful evidence in support of dark matter, as its precise structure is well fitted by the Lambda-CDM model, ^[61] but difficult to reproduce with any competing model such as modified Newtonian dynamics (MOND). ^{[61] [62]}

Structure formation

Main article: Structure formation

Dark matter map for a patch of sky based on gravitational lensing analysis of a Kilo-Degree survey

Structure formation refers to the period after the Big Bang when density perturbations collapsed to form stars, galaxies, and clusters. Prior to structure formation, the Friedmann solutions to general relativity describe a homogeneous universe. Later, small anisotropies gradually grew and condensed the homogeneous universe into stars, galaxies and larger structures. Ordinary matter is affected by radiation, which is the dominant element of the universe at very early times. As a result, its density perturbations are washed out and unable to condense into structure. ^[64] If there were only ordinary matter in the universe, there would not have been enough time for density perturbations to grow into the galaxies and clusters currently seen.

Dark matter provides a solution to this problem because it is unaffected by radiation. Therefore, its density perturbations can grow first. The resulting gravitational potential acts as an attractive potential well for ordinary matter collapsing later, speeding up the structure formation process. ^{[64] [65]}

Bullet Cluster

Main article: Bullet Cluster

The Bullet Cluster is the result of a recent collision of two galaxy clusters. It is of particular note because the location of the center of mass as measured by gravitational lensing is different from the location of the center of mass of visible matter. This is difficult for modified gravity theories, which generally predict lensing around visible matter, to explain. ^{[66] [67] [68] [69]} Standard dark matter theory however has no issue: the hot, visible gas in each cluster would be cooled and slowed down by electromagnetic interactions, while dark matter (which does not interact electromagnetically) would not. This leads to the dark matter separating from the visible gas, producing the separate lensing peak as observed. ^[70]

Type Ia supernova distance measurements

Main articles: Type Ia supernova and Shape of the universe

Type Ia supernovae can be used as standard candles to measure extragalactic distances, which can in turn be used to measure how fast the universe has expanded in the past. ^[71] Data indicates the universe is expanding at an accelerating rate, the cause of which is usually ascribed to dark energy. ^[72] Since observations indicate the universe is almost flat, ^{[73] [74] [75]} it is expected the total energy density of everything in the universe should sum to 1 (Ω_tot ≈ 1). The measured dark energy density is Ω_Λ ≈ 0.690; the observed ordinary (baryonic) matter energy density is Ω_b ≈ 0.0482 and the energy density of radiation is negligible. This leaves a missing Ω_dm ≈ 0.258 which nonetheless behaves like matter (see technical definition section above) –dark matter. ^[76]

Sky surveys and baryon acoustic oscillations

Main article: Baryon acoustic oscillations

Baryon acoustic oscillations (BAO) are fluctuations in the density of the visible baryonic matter (normal matter) of the universe on large scales. These are predicted to arise in the Lambda-CDM model due to acoustic oscillations in the photon–baryon fluid of the early universe and can be observed in the cosmic microwave background angular power spectrum. BAOs set up a preferred length scale for baryons. As the dark matter and baryons clumped together after recombination, the effect is much weaker in the galaxy distribution in the nearby universe, but is detectable as a subtle (≈1 percent) preference for pairs of galaxies to be separated by 147 Mpc, compared to those separated by 130–160 Mpc. This feature was predicted theoretically in the 1990s and then discovered in 2005, in two large galaxy redshift surveys, the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey. ^[77] Combining the CMB observations with BAO measurements from galaxy redshift surveys provides a precise estimate of the Hubble constant and the average matter density in the Universe. ^[78] The results support the Lambda-CDM model.

Redshift-space distortions

Large galaxy redshift surveys may be used to make a three-dimensional map of the galaxy distribution. These maps are slightly distorted because distances are estimated from observed redshifts; the redshift contains a contribution from the galaxy's so-called peculiar velocity in addition to the dominant Hubble expansion term. On average, superclusters are expanding more slowly than the cosmic mean due to their gravity, while voids are expanding faster than average. In a redshift map, galaxies in front of a supercluster have excess radial velocities towards it and have redshifts slightly higher than their distance would imply, while galaxies behind the supercluster have redshifts slightly low for their distance. This effect causes superclusters to appear squashed in the radial direction, and likewise voids are stretched. Their angular positions are unaffected. This effect is not detectable for any one structure since the true shape is not known, but can be measured by averaging over many structures. It was predicted quantitatively by Nick Kaiser in 1987, and first decisively measured in 2001 by the 2dF Galaxy Redshift Survey. ^[79] Results are in agreement with the Lambda-CDM model.

Lyman-alpha forest

Main article: Lyman-alpha forest

In astronomical spectroscopy, the Lyman-alpha forest is the sum of the absorption lines arising from the Lyman-alpha transition of neutral hydrogen in the spectra of distant galaxies and quasars. Lyman-alpha forest observations can also constrain cosmological models. ^[80] These constraints agree with those obtained from WMAP data.

Theoretical classifications

Main articles: Cold dark matter, Warm dark matter, and Hot dark matter

Dark matter can be divided into cold, warm, and hot categories. ^[81] These categories refer to velocity rather than an actual temperature, and indicate how far corresponding objects moved due to random motions in the early universe, before they slowed due to cosmic expansion. This distance is called the free streaming length (FSL). The categories of dark matter are set with respect to the size of a protogalaxy (an object that later evolves into a dwarf galaxy): dark matter particles are classified as cold, warm, or hot if their FSL is much smaller (cold), similar to (warm), or much larger (hot) than a protogalaxy. ^{[82] [83] [84]} Mixtures of the above are also possible: a theory of mixed dark matter was popular in the mid-1990s, but was rejected following the discovery of dark energy.^{[ citation needed ]}

The significance of the free streaming length is that the universe began with some primordial density fluctuations from the Big Bang (in turn arising from quantum fluctuations at the microscale). Particles from overdense regions will naturally spread to underdense regions, but because the universe is expanding quickly, there is a time limit for them to do so. Faster particles (hot dark matter) can beat the time limit while slower particles cannot. The particles travel a free streaming length's worth of distance within the time limit; therefore this length sets a minimum scale for later structure formation. Because galaxy-size density fluctuations get washed out by free-streaming, hot dark matter implies the first objects that can form are huge supercluster-size pancakes, which then fragment into galaxies, while the reverse is true for cold dark matter.

Deep-field observations show that galaxies formed first, followed by clusters and superclusters as galaxies clump together, ^[48] and therefore that most dark matter is cold. This is also the reason why neutrinos, which move at nearly the speed of light and therefore would fall under hot dark matter, cannot make up the bulk of dark matter. ^[64]

Composition

Different dark matter candidates as a function of their mass in units of electronvolt (eV)

The identity of dark matter is unknown, but there are many hypotheses about what dark matter could consist of, as set out in the table below.

Some dark matter hypotheses

Light bosons	quantum chromodynamics axions
	axion-like particles
	fuzzy cold dark matter
neutrinos	Standard Model [d]
	sterile neutrinos
weak scale	supersymmetry
	extra dimensions
	little Higgs
	effective field theory
	simplified models
other particles	weakly interacting massive particle
	self-interacting dark matter
	atomic dark matter [86] [87] [88] [89]
strangelet [90]
superfluid vacuum theory
dynamical dark matter [91]
macroscopic	primordial black holes [13] [14] [92] [15] [93] [94] [95] [96] [97] [98]
	massive compact halo objects (MACHOs)
	macroscopic dark matter (Macros)
modified gravity (MOG)	modified Newtonian dynamics (MoND)
	tensor–vector–scalar gravity (TeVeS)
	entropic gravity

Fermi-LAT observations of dwarf galaxies provide new insights on dark matter.

Baryonic matter

Not to be confused with Missing baryon problem.

Dark matter can refer to any substance which interacts predominantly via gravity with visible matter (e.g., stars and planets). Hence in principle it need not be composed of a new type of fundamental particle but could, at least in part, be made up of standard baryonic matter, such as protons or neutrons. Most of the ordinary matter familiar to astronomers, including planets, brown dwarfs, red dwarfs, visible stars, white dwarfs, neutron stars, and black holes, fall into this category. ^{[18] [99]} A black hole would ingest both baryonic and non-baryonic matter that comes close enough to its event horizon; afterwards, the distinction between the two is lost. ^[100]

These massive objects that are hard to detect are collectively known as MACHOs. Some scientists initially hoped that baryonic MACHOs could account for and explain all the dark matter. ^{[45] : 286  [101]}

However, multiple lines of evidence suggest the majority of dark matter is not baryonic:

• Sufficient diffuse, baryonic gas or dust would be visible when backlit by stars.
• The theory of Big Bang nucleosynthesis predicts the observed abundance of the chemical elements. If there are more baryons, then there should also be more helium, lithium and heavier elements synthesized during the Big Bang. ^{[102] [103]} Agreement with observed abundances requires that baryonic matter makes up between 4–5% of the universe's critical density. In contrast, large-scale structure and other observations indicate that the total matter density is about 30% of the critical density. ^[76]
• Astronomical searches for gravitational microlensing in the Milky Way found at most only a small fraction of the dark matter may be in dark, compact, conventional objects (MACHOs, etc.); the excluded range of object masses is from half the Earth's mass up to 30 solar masses, which covers nearly all the plausible candidates. ^{[104] [105] [106] [107] [108] [109]}
• Detailed analysis of the small irregularities (anisotropies) in the cosmic microwave background by WMAP and Planck indicate that around five-sixths of the total matter is in a form that only interacts significantly with ordinary matter or photons through gravitational effects. ^[110]

Non-baryonic matter

If baryonic matter cannot make up most of dark matter, then dark matter must be non-baryonic. There are two main candidates for non-baryonic dark matter: new hypothetical particles and primordial black holes.

Unlike baryonic matter, nonbaryonic particles do not contribute to the formation of the elements in the early universe (Big Bang nucleosynthesis) ^[46] and so its presence is felt only via its gravitational effects (such as weak lensing). In addition, some dark matter candidates can interact with themselves (self-interacting dark matter) or with ordinary particles (e.g. WIMPs or Weakly Interacting Massive Particles), possibly resulting in observable by-products such as gamma rays and neutrinos (indirect detection). ^[85] Candidates abound (see the table above), each with their own strengths and weaknesses.

Undiscovered massive particles

Main article: Weakly Interacting Massive Particles

There exists no formal definition of a Weakly Interacting Massive Particle, but broadly, it is an elementary particle which interacts via gravity and any other force (or forces) which is as weak as or weaker than the weak nuclear force, but also non-vanishing in strength. Many WIMP candidates are expected to have been produced thermally in the early Universe, similarly to the particles of the Standard Model ^[111] according to Big Bang cosmology, and usually will constitute cold dark matter. Obtaining the correct abundance of dark matter today via thermal production requires a self-annihilation cross section of ${\displaystyle \langle \sigma v\rangle \simeq 3\times 10^{-26}\mathrm {cm} ^{3}\;\mathrm {s} ^{-1}}$, which is roughly what is expected for a new particle in the 100  GeV mass range that interacts via the electroweak force.

Because supersymmetric extensions of the Standard Model of particle physics readily predict a new particle with these properties, this apparent coincidence is known as the "WIMP miracle", and a stable supersymmetric partner has long been a prime explanation for dark matter. ^[112] Experimental efforts to detect WIMPs include the search for products of WIMP annihilation, including gamma rays, neutrinos and cosmic rays in nearby galaxies and galaxy clusters; direct detection experiments designed to measure the collision of WIMPs with nuclei in the laboratory, as well as attempts to directly produce WIMPs in colliders, such as the Large Hadron Collider at CERN.

In the early 2010s, results from direct-detection experiments along with the lack of evidence for supersymmetry at the Large Hadron Collider (LHC) experiment ^{[113] [114]} have cast doubt on the simplest WIMP hypothesis. ^[115]

Undiscovered ultralight particles

Main article: Axion

Axions are hypothetical elementary particles 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). QCD effects produce an effective periodic potential in which the axion field moves. ^[116] Expanding the potential about one of its minima, one finds that the product of the axion mass with the axion decay constant is determined by the topological susceptibility of the QCD vacuum. An axion with mass much less than 60 keV is long-lived and weakly interacting: A perfect dark matter candidate.

The oscillations of the axion field about the minimum of the effective potential, the so-called misalignment mechanism, generate a cosmological population of cold axions with an abundance depending on the mass of the axion. ^{[117] [118] [119]} With a mass above 5  μeV/c² (10⁻¹¹ times the electron mass) axions could account for dark matter, and thus be both a dark-matter candidate and a solution to the strong CP problem. If inflation occurs at a low scale and lasts sufficiently long, the axion mass can be as low as 1 peV/c². ^{[120] [121] [122]}

Because axions have extremely low mass, their de Broglie wavelength is very large, in turn meaning that quantum effects could help resolve the small-scale problems of the Lambda-CDM model. A single ultralight axion with a decay constant at the grand unified theory scale provides the correct relic density without fine-tuning. ^[123]

Axions as a dark matter candidate has gained in popularity in recent years, because of the non-detection of WIMPS. ^[124]

Primordial Black holes

Main article: Primordial black hole

Primordial black holes 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 and also not classified as baryonic dark matter.

The idea that black holes could form in the early universe was first suggested by Yakov Zeldovich and Igor Dmitriyevich Novikov in 1967, and independently by Stephen Hawking in 1971. It quickly became clear that such black holes might account for at least part of dark matter. Primordial black holes as a dark matter candidate has the major advantage that it is based on a well-understood theory (General Relativity) and objects (black holes) that are already known to exist. However, producing primordial black holes requires exotic cosmic inflation or physics beyond the standard model of particle physics, ^[125] and might also require fine-tuning. ^[126] Primordial black holes can also span nearly the entire possible mass range, from atom-sized to supermassive.

The idea that primordial black holes make up dark matter gained prominence in 2015 ^[127] following results of gravitational wave measurements which detected the merger of intermediate-mass black holes. Black holes with about 30 solar masses are not predicted to form by either stellar collapse (typically less than 15 solar masses) or by the merger of black holes in galactic centers (millions or billions of solar masses), which suggests that the detected black holes might be primordial. A later survey of about a thousand supernovae detected no gravitational lensing events, when about eight would be expected if intermediate-mass primordial black holes above a certain mass range accounted for over 60% of dark matter. ^[128] However, that study assumed that all black holes have the same or similar mass to the LIGO/Virgo mass range, which might not be the case (as suggested by subsequent James Webb Space Telescope observations). ^{[129] [92]}

The possibility that atom-sized primordial black holes account for a significant fraction of dark matter was ruled out by measurements of positron and electron fluxes outside the Sun's heliosphere by the Voyager 1 spacecraft. Tiny black holes are theorized to emit Hawking radiation. However the detected fluxes were too low and did not have the expected energy spectrum, suggesting that tiny primordial black holes are not widespread enough to account for dark matter. ^[130] Nonetheless, research and theories proposing dense dark matter accounts for dark matter continue as of 2018, including approaches to dark matter cooling, ^{[131] [132]} and the question remains unsettled. In 2019, the lack of microlensing effects in the observation of Andromeda suggests that tiny black holes do not exist. ^[133]

Nonetheless, there still exists a largely unconstrained mass range smaller than that which can be limited by optical microlensing observations, where primordial black holes may account for all dark matter. ^{[134] [135]}

Dark matter aggregation and dense dark matter objects

If dark matter is composed of weakly interacting particles, then an obvious question is whether it can form objects equivalent to planets, stars, or black holes. Historically, the answer has been it cannot, ^{[e] [136] [137] [138]} because of two factors:

It lacks an efficient means to lose energy ^[136]

Ordinary matter forms dense objects because it has numerous ways to lose energy. Losing energy would be essential for object formation, because a particle that gains energy during compaction or falling "inward" under gravity, and cannot lose it any other way, will heat up and increase velocity and momentum. Dark matter appears to lack a means to lose energy, simply because it is not capable of interacting strongly in other ways except through gravity. The virial theorem suggests that such a particle would not stay bound to the gradually forming object – as the object began to form and compact, the dark matter particles within it would speed up and tend to escape.

It lacks a diversity of interactions needed to form structures ^[138]

Ordinary matter interacts in many different ways, which allows the matter to form more complex structures. For example, stars form through gravity, but the particles within them interact and can emit energy in the form of neutrinos and electromagnetic radiation through fusion when they become energetic enough. Protons and neutrons can bind via the strong interaction and then form atoms with electrons largely through electromagnetic interaction. There is no evidence that dark matter is capable of such a wide variety of interactions, since it seems to only interact through gravity (and possibly through some means no stronger than the weak interaction, although until dark matter is better understood, this is only speculation).

Detection of dark matter particles

If dark matter is made up of subatomic particles, then millions, possibly billions, of such particles must pass through every square centimeter of the Earth each second. ^{[139] [140]} Many experiments aim to test this hypothesis. Although WIMPs have been the main search candidates, ^[48] axions have drawn renewed attention, with the Axion Dark Matter Experiment (ADMX) searches for axions and many more planned in the future. ^[141] Another candidate is heavy hidden sector particles which only interact with ordinary matter via gravity.

These experiments can be divided into two classes: direct detection experiments, which search for the scattering of dark matter particles off atomic nuclei within a detector; and indirect detection, which look for the products of dark matter particle annihilations or decays. ^[85]

Direct detection

Further information: Weakly interacting massive particle § Direct detection

Main article: Direct detection of dark matter

Direct detection experiments aim to observe low-energy recoils (typically a few keVs) of nuclei induced by interactions with particles of dark matter, which (in theory) are passing through the Earth. After such a recoil, the nucleus will emit energy in the form of scintillation light or phonons as they pass through sensitive detection apparatus. To do so effectively, it is crucial to maintain an extremely low background, which is the reason why such experiments typically operate deep underground, where interference from cosmic rays is minimized. Examples of underground laboratories with direct detection experiments include the Stawell mine, the Soudan mine, the SNOLAB underground laboratory at Sudbury, the Gran Sasso National Laboratory, the Canfranc Underground Laboratory, the Boulby Underground Laboratory, the Deep Underground Science and Engineering Laboratory and the China Jinping Underground Laboratory.

These experiments mostly use either cryogenic or noble liquid detector technologies. Cryogenic detectors operating at temperatures below 100 mK, detect the heat produced when a particle hits an atom in a crystal absorber such as germanium. Noble liquid detectors detect scintillation produced by a particle collision in liquid xenon or argon. Cryogenic detector experiments include such projects as CDMS, CRESST, EDELWEISS, and EURECA, while noble liquid experiments include LZ, XENON, DEAP, ArDM, WARP, DarkSide, PandaX, and LUX, the Large Underground Xenon experiment. Both of these techniques focus strongly on their ability to distinguish background particles (which predominantly scatter off electrons) from dark matter particles (that scatter off nuclei). Other experiments include SIMPLE and PICASSO, which use alternative methods in their attempts to detect dark matter.

Currently there has been no well-established claim of dark matter detection from a direct detection experiment, leading instead to strong upper limits on the mass and interaction cross section with nucleons of such dark matter particles. ^[142] The DAMA/NaI and more recent DAMA/LIBRA experimental collaborations have detected an annual modulation in the rate of events in their detectors, ^{[143] [144]} which they claim is due to dark matter. This results from the expectation that as the Earth orbits the Sun, the velocity of the detector relative to the dark matter halo will vary by a small amount. This claim is so far unconfirmed and in contradiction with negative results from other experiments such as LUX, SuperCDMS ^[145] and XENON100. ^[146]

A special case of direct detection experiments covers those with directional sensitivity. This is a search strategy based on the motion of the Solar System around the Galactic Center. ^{[147] [148] [149] [150]} A low-pressure time projection chamber makes it possible to access information on recoiling tracks and constrain WIMP-nucleus kinematics. WIMPs coming from the direction in which the Sun travels (approximately towards Cygnus) may then be separated from background, which should be isotropic. Directional dark matter experiments include DMTPC, DRIFT, Newage and MIMAC.

Indirect detection

Main article: Indirect detection of dark matter

Collage of six cluster collisions with dark matter maps. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide.

Video about the potential gamma-ray detection of dark matter annihilation around supermassive black holes. (Duration 0:03:13, also see file description.)

Indirect detection experiments search for the products of the self-annihilation or decay of dark matter particles in outer space. For example, in regions of high dark matter density (e.g., the centre of the Milky Way) two dark matter particles could annihilate to produce gamma rays or Standard Model particle–antiparticle pairs. ^[152] Alternatively, if a dark matter particle is unstable, it could decay into Standard Model (or other) particles. These processes could be detected indirectly through an excess of gamma rays, antiprotons or positrons emanating from high density regions in the Milky Way and other galaxies. ^[153] A major difficulty inherent in such searches is that various astrophysical sources can mimic the signal expected from dark matter, and so multiple signals are likely required for a conclusive discovery. ^{[48] [85]}

A few of the dark matter particles passing through the Sun or Earth may scatter off atoms and lose energy. Thus dark matter may accumulate at the center of these bodies, increasing the chance of collision/annihilation. This could produce a distinctive signal in the form of high-energy neutrinos. ^[154] Such a signal would be strong indirect proof of WIMP dark matter. ^[48] High-energy neutrino telescopes such as AMANDA, IceCube and ANTARES are searching for this signal. ^{[45] : 298} The detection by LIGO in September 2015 of gravitational waves opens the possibility of observing dark matter in a new way, particularly if it is in the form of primordial black holes. ^{[155] [156] [157]}

Many experimental searches have been undertaken to look for such emission from dark matter annihilation or decay, examples of which follow.

The Energetic Gamma Ray Experiment Telescope observed more gamma rays in 2008 than expected from the Milky Way, but scientists concluded this was most likely due to incorrect estimation of the telescope's sensitivity. ^[158]

The Fermi Gamma-ray Space Telescope is searching for similar gamma rays. ^[159] In 2009, an as yet unexplained surplus of gamma rays from the Milky Way's galactic center was found in Fermi data. This Galactic Center GeV excess might be due to dark matter annihilation or to a population of pulsars. ^[160] In April 2012, an analysis of previously available data from Fermi's Large Area Telescope instrument produced statistical evidence of a 130 GeV signal in the gamma radiation coming from the center of the Milky Way. ^[161] WIMP annihilation was seen as the most probable explanation. ^[162]

At higher energies, ground-based gamma-ray telescopes have set limits on the annihilation of dark matter in dwarf spheroidal galaxies ^[163] and in clusters of galaxies. ^[164]

The PAMELA experiment (launched in 2006) detected excess positrons. They could be from dark matter annihilation or from pulsars. No excess antiprotons were observed. ^[165]

In 2013, results from the Alpha Magnetic Spectrometer on the International Space Station indicated excess high-energy cosmic rays which could be due to dark matter annihilation. ^{[166] [167] [168] [169] [170] [171]}

Collider searches for dark matter

An alternative approach to the detection of dark matter particles in nature is to produce them in a laboratory. Experiments with the Large Hadron Collider (LHC) may be able to detect dark matter particles produced in collisions of the LHC proton beams. Because a dark matter particle should have negligible interactions with normal visible matter, it may be detected indirectly as (large amounts of) missing energy and momentum that escape the detectors, provided other (non-negligible) collision products are detected. ^[172] Constraints on dark matter also exist from the LEP experiment using a similar principle, but probing the interaction of dark matter particles with electrons rather than quarks. ^[173] Any discovery from collider searches must be corroborated by discoveries in the indirect or direct detection sectors to prove that the particle discovered is, in fact, dark matter.

Alternative hypotheses

Further information: Alternatives to general relativity

Because dark matter has not yet been identified, many other hypotheses have emerged aiming to explain the same observational phenomena without introducing a new unknown type of matter. The theory underpinning most observational evidence for dark matter, general relativity, is well-tested on Solar System scales, but its validity on galactic or cosmological scales has not been well proven. ^[174] A suitable modification to general relativity can in principle conceivably eliminate the need for dark matter. The best-known theories of this class are MOND and its relativistic generalization tensor–vector–scalar gravity (TeVeS), ^[175] f(R) gravity, ^[176] negative mass, dark fluid, ^{[177] [178] [179]} and entropic gravity. ^[180] Alternative theories abound. ^{[181] [182]}

A problem with alternative hypotheses is that observational evidence for dark matter comes from so many independent approaches (see the "observational evidence" section above). Explaining any individual observation is possible but explaining all of them in the absence of dark matter is very difficult. Nonetheless, there have been some scattered successes for alternative hypotheses, such as a 2016 test of gravitational lensing in entropic gravity ^{[183] [184] [185]} and a 2020 measurement of a unique MOND effect. ^{[186] [187]}

The prevailing opinion among most astrophysicists is that while modifications to general relativity can conceivably explain part of the observational evidence, there is probably enough data to conclude there must be some form of dark matter present in the universe. ^[17]

In popular culture

Dark matter regularly appears as a topic in hybrid periodicals that cover both factual scientific topics and science fiction, ^[188] and dark matter itself has been referred to as "the stuff of science fiction". ^[189]

Mention of dark matter is made in works of fiction. In such cases, it is usually attributed extraordinary physical or magical properties, thus becoming inconsistent with the hypothesized properties of dark matter in physics and cosmology. For example:

• Dark matter serves as a plot device in the 1995 X-Files episode "Soft Light". ^[190]
• A dark-matter-inspired substance known as "Dust" features prominently in Philip Pullman's His Dark Materials trilogy. ^[191]
• Beings made of dark matter are antagonists in Stephen Baxter's Xeelee Sequence . ^[192]

More broadly, the phrase "dark matter" is used metaphorically in fiction to evoke the unseen or invisible. ^[193]

Gallery

• 
  DM map by the Cosmic Evolution Survey (COSMOS) using the Hubble Space Telescope (2007) ^{[194] [195]}
• 
  DM map by the CFHT Lensing Survey (CFHTLenS) using the Canada–France–Hawaii Telescope (2012) ^{[196] [197]} (COSMOS map at the center)
• 
  DM map by the Kilo-Degree Survey (KiDS) using the VLT Survey Telescope (2015) ^{[198] [199]}
• 
  DM map by the Hyper Suprime-Cam Survey (HSCS) using the Subaru Telescope (2018) ^{[200] [201]}
• 
  DM map by the Dark Energy Survey (DES) using the Víctor M. Blanco Telescope (2021) ^{[202] [203]}

See also

Related theories

• Dark energy  – Energy driving the accelerated expansion of the universe
• Conformal gravity  – Gravity theories that are invariant under Weyl transformations
• Density wave theory – A theory in which waves of compressed gas, which move slower than the galaxy, maintain galaxy's structure
• Entropic gravity  – Theory in modern physics that describes gravity as an entropic force
• Dark radiation  – Postulated type of radiation that mediates interactions of dark matter
• Massive gravity  – Theory of gravity in which the graviton has nonzero mass
• Unparticle physics  – Speculative theory that conjectures a form of matter that cannot be explained in terms of particles

Experiments

• DEAP  – Dark matter search experiment, a search apparatus
• LZ experiment  – experiment in South Dakota, United StatesPages displaying wikidata descriptions as a fallback, large underground dark matter detector
• Dark Matter Particle Explorer (DAMPE) – Chinese science satellite, a space mission
• General antiparticle spectrometer
• MultiDark, a research program
• Illustris project  – Computer-simulated universes, astrophysical simulations
• Future Circular Collider  – Proposed particle accelerator, a particle accelerator research infrastructure

Dark matter candidates

• Feebly Interacting Particles
• Light dark matter  – Dark matter weakly interacting massive particles candidates with masses less than 1 GeV
• Mirror matter  – Hypothetical counterpart to ordinary matter
• Exotic matter  – Physics term for multiple concepts
• Neutralino  – Neutral mass eigenstate formed from superpartners of gauge and Higgs bosons
• Dark galaxy  – A hypothesized galaxy with no, or very few, stars
• Scalar field dark matter  – Classical, minimally coupled, scalar field postulated to account for the inferred dark matter
• Self-interacting dark matter  – Hypothetical form of dark matter consisting of particles with strong self-interactions
• Weakly interacting massive particle (WIMP) – Hypothetical particles that may constitute dark matter
• Weakly interacting slim particle (WISP) –Low-mass counterpart to WIMP
• Strongly interacting massive particle (SIMP) – Hypothetical particle
• Chameleon particle  – Hypothetical scalar particle that couples to matter more weakly than gravity

Other

• Galactic Center GeV excess  – Unexplained gamma rays from the Galactic Center
• Luminiferous aether – A once theorized invisible and infinite material with no interaction with physical objects, used to explain how light could travel through a vacuum (now disproven)

Notes

1. "Um, wie beobachtet, einen mittleren Dopplereffekt von 1000 km/sek oder mehr zu erhalten, müsste also die mittlere Dichte im Comasystem mindestens 400 mal grösser sein als die auf Grund von Beobachtungen an leuchtender Materie abgeleitete. Falls sich dies bewahrheiten sollte, würde sich also das überraschende Resultat ergeben, dass dunkle Materie in sehr viel grösserer Dichte vorhanden ist als leuchtende Materie." ^{[29] (p 125)}

   [In order to obtain an average Doppler effect of 1000 km/s or more, as observed, the average density in the Coma system would thus have to be at least 400 times greater than that derived on the basis of observations of luminous matter. If this were to be confirmed, the surprising result would then follow that dark matter is present in very much greater density than luminous matter.]

2. However, in the modern cosmic era, this neutrino field has cooled and started to behave more like matter and less like radiation.
3. This is a consequence of the shell theorem and the observation that spiral galaxies are spherically symmetric to a large extent (in 2D).
4. The three neutrino types already observed are indeed abundant, and dark, and matter, but their individual masses are almost certainly too tiny to account for more than a small fraction of dark matter, due to limits derived from large-scale structure and high-redshift galaxies. ^[85]
5. "One widely held belief about dark matter is it cannot cool off by radiating energy. If it could, then it might bunch together and create compact objects in the same way baryonic matter forms planets, stars, and galaxies. Observations so far suggest dark matter doesn't do that – it resides only in diffuse halos ... As a result, it is extremely unlikely there are very dense objects like stars made out of entirely (or even mostly) dark matter." — Buckley & Difranzo (2018) ^[136]

References

1. Siegfried, T. (5 July 1999). "Hidden space dimensions may permit parallel universes, explain cosmic mysteries". The Dallas Morning News.
2. Trimble, V. (1987). "Existence and nature of dark matter in the universe" (PDF). Annual Review of Astronomy and Astrophysics . 25: 425–472. Bibcode:1987ARA&A..25..425T. doi:10.1146/annurev.aa.25.090187.002233. ISSN   0066-4146. S2CID   123199266. Archived (PDF) from the original on 18 July 2018.
3. "A history of dark matter". 2017.
4. "Planck Mission Brings Universe into Sharp Focus". NASA Mission Pages. 21 March 2013. Archived from the original on 12 November 2020. Retrieved 1 May 2016.
5. "Dark Energy, Dark Matter". NASA Science: Astrophysics. 5 June 2015.
6. Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; et al. (Planck Collaboration) (22 March 2013). "Planck 2013 results. I. Overview of products and scientific results – Table 9". Astronomy and Astrophysics . 1303: 5062. arXiv: 1303.5062 . Bibcode:2014A&A...571A...1P. doi:10.1051/0004-6361/201321529. S2CID   218716838.
7. Francis, Matthew (22 March 2013). "First Planck results: the Universe is still weird and interesting". Ars Technica.
8. "Planck captures portrait of the young Universe, revealing earliest light". University of Cambridge. 21 March 2013. Retrieved 21 March 2013.
9. Carroll, Sean (2007). Dark Matter, Dark Energy: The dark side of the universe. The Teaching Company. Guidebook Part 2 p. 46. ... dark matter: An invisible, essentially collisionless component of matter that makes up about 25 percent of the energy density of the universe ... it's a different kind of particle... something not yet observed in the laboratory ...
10. Ferris, Timothy (January 2015). "Dark matter". Hidden cosmos. National Geographic Magazine. Archived from the original on 25 December 2014. Retrieved 10 June 2015.
11. Jarosik, N.; et al. (2011). "Seven-year Wilson microwave anisotropy probe (WMAP) observations: Sky maps, systematic errors, and basic results". Astrophysical Journal Supplement . 192 (2): 14. arXiv: 1001.4744 . Bibcode:2011ApJS..192...14J. doi:10.1088/0067-0049/192/2/14. S2CID   46171526.
12. Timmer, John (21 April 2023). "No WIMPS! Heavy particles don't explain gravitational lensing oddities". Ars Technica. Retrieved 21 June 2023.
13. Carr, B. J.; Clesse, S.; García-Bellido, J.; Hawkins, M. R. S.; Kühnel, F. (26 February 2024). "Observational evidence for primordial black holes: A positivist perspective". Physics Reports. 1054: 1–68. arXiv: 2306.03903 . Bibcode:2024PhR..1054....1C. doi:10.1016/j.physrep.2023.11.005. ISSN   0370-1573. See Figure 39.
14. Bird, Simeon; Albert, Andrea; Dawson, Will; Ali-Haïmoud, Yacine; Coogan, Adam; Drlica-Wagner, Alex; Feng, Qi; Inman, Derek; Inomata, Keisuke; Kovetz, Ely; Kusenko, Alexander; Lehmann, Benjamin V.; Muñoz, Julian B.; Singh, Rajeev; Takhistov, Volodymyr; Tsai, Yu-Dai (1 August 2023). "Primordial black hole dark matter". Physics of the Dark Universe. 41: 101231. arXiv: 2203.08967 . doi:10.1016/j.dark.2023.101231. ISSN   2212-6864. S2CID   247518939.
15. Carr, Bernard; Kühnel, Florian (2 May 2022). "Primordial black holes as dark matter candidates". SciPost Physics Lecture Notes: 48. arXiv: 2110.02821 . doi: 10.21468/SciPostPhysLectNotes.48 . S2CID   238407875 . Retrieved 13 February 2023. (See also the accompanying slide presentation.
16. Hossenfelder, Sabine; McGaugh, Stacy S. (August 2018). "Is dark matter real?". Scientific American. 319 (2): 36–43. Bibcode:2018SciAm.319b..36H. doi:10.1038/scientificamerican0818-36. PMID   30020902. S2CID   51697421. Right now a few dozens of scientists are studying modified gravity, whereas several thousand are looking for particle dark matter.
17. Carroll, Sean (9 May 2012). "Dark matter vs. modified gravity: A trialogue" . Retrieved 14 February 2017.
18. Bertone, Gianfranco; Hooper, Dan (15 October 2018). "History of dark matter". Reviews of Modern Physics. 90 (4): 045002. arXiv: 1605.04909 . Bibcode:2018RvMP...90d5002B. doi:10.1103/RevModPhys.90.045002. S2CID   18596513.
19. de Swart, J.G.; Bertone, G.; van Dongen, J. (2017). "How dark matter came to matter". Nature Astronomy . 1 (59): 59. arXiv: 1703.00013 . Bibcode:2017NatAs...1E..59D. doi:10.1038/s41550-017-0059. S2CID   119092226.
20. Thompson, W., Lord Kelvin (1904). Baltimore Lectures on Molecular Dynamics and the Wave Theory of Light. London, UK: C.J. Clay and Sons. p. 274 – via hathitrust.org.
21. "A history of dark matter". Ars Technica . 3 February 2017. Retrieved 8 February 2017.
22. Poincaré, H. (1906). "La Voie lactée et la théorie des gaz" [The Milky Way and the theory of gases]. Bulletin de la Société astronomique de France (in French). 20: 153–165.
23. Kapteyn, J.C. (1922). "First attempt at a theory of the arrangement and motion of the sidereal system". Astrophysical Journal. 55: 302–327. Bibcode:1922ApJ....55..302K. doi:10.1086/142670. It is incidentally suggested when the theory is perfected it may be possible to determine the amount of dark matter from its gravitational effect. [emphasis in original]
24. Rosenberg, Leslie J. (30 June 2014). Status of the Axion Dark-Matter Experiment (ADMX) (PDF). 10th PATRAS Workshop on Axions, WIMPs and WISPs. p. 2. Archived (PDF) from the original on 5 February 2016.
25. Lundmark, K. (1 January 1930). "Über die Bestimmung der Entfernungen, Dimensionen, Massen, und Dichtigkeit fur die nächstgelegenen anagalacktischen Sternsysteme" [On determination of distances, dimensions, masses, and densities for the nearest non-galactic star systems]. Meddelanden Fran Lunds Astronomiska Observatorium (in German). 125: 1–13. Bibcode:1930MeLuF.125....1L.
26. Oort, J.H. (1932). "The force exerted by the stellar system in the direction perpendicular to the galactic plane and some related problems". Bulletin of the Astronomical Institutes of the Netherlands. 6: 249–287. Bibcode:1932BAN.....6..249O.
27. "The hidden lives of galaxies: Hidden mass". Imagine the Universe. Greenbelt, MD: NASA / GSFC.
28. Kuijken, K.; Gilmore, G. (July 1989). "The Mass Distribution in the Galactic Disc – Part III – the Local Volume Mass Density". Monthly Notices of the Royal Astronomical Society . 239 (2): 651–664. Bibcode:1989MNRAS.239..651K. doi: 10.1093/mnras/239.2.651 .
29. Zwicky, F. (1933). "Die Rotverschiebung von extragalaktischen Nebeln" [The red shift of extragalactic nebulae]. Helvetica Physica Acta . 6: 110–127. Bibcode:1933AcHPh...6..110Z.
30. Zwicky, Fritz (1937). "On the Masses of Nebulae and of Clusters of Nebulae". The Astrophysical Journal . 86: 217–246. Bibcode:1937ApJ....86..217Z. doi: 10.1086/143864 .
31. Some details of Zwicky's calculation and of more modern values are given in Richmond, M. (c. 1999). Using the virial theorem: The mass of a cluster of galaxies (lecture notes). Physics 440. Rochester, NY: Rochester Institute of Technology . Retrieved 10 July 2007– via spiff.rit.edu.
32. Freese, Katherine (2014). The Cosmic Cocktail: Three parts dark matter. Princeton University Press. ISBN   978-1-4008-5007-5.
33. Babcock, H.W. (1939). "The rotation of the Andromeda Nebula". Lick Observatory Bulletin . 19: 41–51. Bibcode:1939LicOB..19...41B. doi: 10.5479/ADS/bib/1939LicOB.19.41B .
34. Oort, J.H. (April 1940). "Some problems concerning the structure and dynamics of the galactic system and the elliptical nebulae NGC 3115 and 4494" (PDF). The Astrophysical Journal . 91 (3): 273–306. Bibcode:1940ApJ....91..273O. doi:10.1086/144167. hdl: 1887/8533 – via leidenuniv.nl.
35. de Swart, Jaco (1 August 2024). "Five decades of missing mass". Physics Today . 77: 34–43. doi: 10.1063/pt.ozhk.lfeb .
36. Overbye, D. (27 December 2016). "Vera Rubin, 88, dies; opened doors in astronomy, and for women". The New York Times (obituary). Retrieved 27 December 2016.
37. "First observational evidence of dark matter". Darkmatterphysics.com. Archived from the original on 25 June 2013. Retrieved 6 August 2013.
38. Rubin, V.C.; Ford, W.K. Jr. (February 1970). "Rotation of the Andromeda nebula from a spectroscopic survey of emission regions". The Astrophysical Journal . 159: 379–403. Bibcode:1970ApJ...159..379R. doi:10.1086/150317. S2CID   122756867.
39. Roberts, Morton S. (May 1966). "A high-resolution 21 cm hydrogen-line survey of the Andromeda nebula". The Astrophysical Journal . 159: 639–656. Bibcode:1966ApJ...144..639R. doi:10.1086/148645.
40. Gottesman, S. T.; Davies, Rod D.; Reddish, Vincent Cartledge (1966). "A neutral hydrogen survey of the southern regions of the Andromeda nebula". Monthly Notices of the Royal Astronomical Society . 133 (4): 359–387. Bibcode:1966MNRAS.133..359G. doi: 10.1093/mnras/133.4.359 .
41. Roberts, Morton S. (October 1975). "The rotation curve and geometry of M 31 at large galactocentric distances". The Astrophysical Journal . 201: 327–346. Bibcode:1975ApJ...201..327R. doi:10.1086/153889.
42. Rogstad, David H.; Shostak, G. Seth (September 1972). "Gross properties of five Scd galaxies as determined from 21 centimeter observations". The Astrophysical Journal . 176: 315–321. Bibcode:1972ApJ...176..315R. doi:10.1086/151636.
43. Bosma, A. (1978). The distribution and kinematics of neutral hydrogen in spiral galaxies of various morphological types (Ph.D. thesis). Rijksuniversiteit Groningen.
44. Persic, Massimo; Salucci, Paolo; Stel, Fulvio (1996). "The universal rotation curve of spiral galaxies — I. The dark matter connection". Monthly Notices of the Royal Astronomical Society . 281 (1): 27–47. arXiv: astro-ph/9506004 . Bibcode:1996MNRAS.281...27P. doi: 10.1093/mnras/278.1.27 .
45. Randall, Lisa (2015). Dark Matter and the Dinosaurs: The astounding interconnectedness of the Universe. New York, NY: Ecco / HarperCollins Publishers. ISBN   978-0-06-232847-2.
46. Copi, C.J.; Schramm, D.N.; Turner, M.S. (1995). "Big-Bang nucleosynthesis and the baryon density of the universe". Science . 267 (5195): 192–199. arXiv: astro-ph/9407006 . Bibcode:1995Sci...267..192C. doi:10.1126/science.7809624. PMID   7809624. S2CID   15613185.
47. Bergstrom, L. (2000). "Non-baryonic dark matter: Observational evidence and detection methods". Reports on Progress in Physics . 63 (5): 793–841. arXiv: hep-ph/0002126 . Bibcode:2000RPPh...63..793B. doi:10.1088/0034-4885/63/5/2r3. S2CID   119349858.
48. Bertone, G.; Hooper, D.; Silk, J. (2005). "Particle dark matter: Evidence, candidates, and constraints". Physics Reports . 405 (5–6): 279–390. arXiv: hep-ph/0404175 . Bibcode:2005PhR...405..279B. doi:10.1016/j.physrep.2004.08.031. S2CID   118979310.
49. Baumann, Daniel. "Cosmology: Part III" (PDF). Mathematical Tripos. Cambridge University. pp. 21–22. Archived from the original (PDF) on 2 February 2017. Retrieved 24 January 2017.
50. Siegel, Ethan (2019). "Is energy conserved when photons redshift in our expanding universe?". Starts With a Bang . Retrieved 5 November 2022.
51. Peter, Annika H. G. (18 January 2012). "Dark Matter: A Brief Review". arXiv: 1201.3942 [astro-ph.CO].
52. Salucci, P. (2019). "The distribution of dark matter in galaxies". The Astronomy and Astrophysics Review . 27 (1): 2. arXiv: 1811.08843 . Bibcode:2019A&ARv..27....2S. doi:10.1007/s00159-018-0113-1.
53. Faber, S. M.; Jackson, R. E. (1976). "Velocity dispersions and mass-to-light ratios for elliptical galaxies". The Astrophysical Journal. 204: 668–683. Bibcode:1976ApJ...204..668F. doi:10.1086/154215.
54. Binny, James; Merrifield, Michael (1998). Galactic Astronomy. Princeton University Press. pp. 712–713.
55. Allen, Steven W.; Evrard, August E.; Mantz, Adam B. (2011). "Cosmological Parameters from Clusters of Galaxies". Annual Review of Astronomy and Astrophysics . 49 (1): 409–470. arXiv: 1103.4829 . Bibcode:2011ARA&A..49..409A. doi:10.1146/annurev-astro-081710-102514. S2CID   54922695.
56. Taylor, A. N.; et al. (1998). "Gravitational lens magnification and the mass of Abell 1689". The Astrophysical Journal. 501 (2): 539–553. arXiv: astro-ph/9801158 . Bibcode:1998ApJ...501..539T. doi:10.1086/305827. S2CID   14446661.
57. Refregier, A. (2003). "Weak gravitational lensing by large-scale structure". Annual Review of Astronomy and Astrophysics . 41 (1): 645–668. arXiv: astro-ph/0307212 . Bibcode:2003ARA&A..41..645R. doi:10.1146/annurev.astro.41.111302.102207. S2CID   34450722.
58. Wu, X.; Chiueh, T.; Fang, L.; Xue, Y. (1998). "A comparison of different cluster mass estimates: consistency or discrepancy?". Monthly Notices of the Royal Astronomical Society . 301 (3): 861–871. arXiv: astro-ph/9808179 . Bibcode:1998MNRAS.301..861W. CiteSeerX   10.1.1.256.8523 . doi: 10.1046/j.1365-8711.1998.02055.x . S2CID   1291475.
59. The details are technical. For an intermediate-level introduction, see Hu, Wayne (2001). "Intermediate Guide to the Acoustic Peaks and Polarization".
60. Hinshaw, G.; et al. (2009). "Five-year Wilkinson microwave anisotropy probe (WMAP) observations: Data processing, sky maps, and basic results". The Astrophysical Journal Supplement. 180 (2): 225–245. arXiv: 0803.0732 . Bibcode:2009ApJS..180..225H. doi:10.1088/0067-0049/180/2/225. S2CID   3629998.
61. Ade, P.A.R.; et al. (2016). "Planck 2015 results. XIII. Cosmological parameters". Astron. Astrophys. 594 (13): A13. arXiv: 1502.01589 . Bibcode:2016A&A...594A..13P. doi:10.1051/0004-6361/201525830. S2CID   119262962.
62. Skordis, C.; et al. (2006). "Large scale structure in Bekenstein's theory of relativistic modified Newtonian dynamics". Phys. Rev. Lett. 96 (1): 011301. arXiv: astro-ph/0505519 . Bibcode:2006PhRvL..96a1301S. doi:10.1103/PhysRevLett.96.011301. PMID   16486433. S2CID   46508316.
63. "Dark matter may be smoother than expected – Careful study of large area of sky imaged by VST reveals intriguing result". www.eso.org. Retrieved 8 December 2016.
64. Jaffe, A. H. "Cosmology 2012: Lecture Notes" (PDF). Archived from the original (PDF) on 17 July 2016.
65. Low, L. F. (12 October 2016). "Constraints on the composite photon theory". Modern Physics Letters A. 31 (36): 1675002. Bibcode:2016MPLA...3175002L. doi:10.1142/S021773231675002X.
66. Markevitch, M.; Randall, S.; Clowe, D.; Gonzalez, A. & Bradac, M. (16–23 July 2006). Dark matter and the Bullet Cluster (PDF). 36th COSPAR Scientific Assembly. Beijing, China. Archived (PDF) from the original on 21 August 2006. Abstract only
67. Clowe, Douglas; et al. (2006). "A Direct Empirical Proof of the Existence of Dark Matter". The Astrophysical Journal Letters. 648 (2): L109 –L113. arXiv: astro-ph/0608407 . Bibcode:2006ApJ...648L.109C. doi:10.1086/508162. S2CID   2897407.
68. Lee, Chris (21 September 2017). "Science-in-progress: Did the Bullet Cluster withstand scrutiny?". Ars Technica.
69. Siegel, Ethan (9 November 2017). "The Bullet Cluster proves dark matter exists, but not for the reason most physicists think". Forbes.
70. "Bullet Cluster: Direct Proof of Dark Matter" (PDF). NASA.
71. Planck Collaboration; Aghanim, N.; Akrami, Y.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S. (2020). "Planck 2018 results. VI. Cosmological parameters". Astronomy & Astrophysics. 641: A6. arXiv: 1807.06209 . Bibcode:2020A&A...641A...6P. doi:10.1051/0004-6361/201833910. S2CID   119335614.
72. Kowalski, M.; et al. (2008). "Improved Cosmological Constraints from New, Old, and Combined Supernova Data Sets". The Astrophysical Journal. 686 (2): 749–778. arXiv: 0804.4142 . Bibcode:2008ApJ...686..749K. doi:10.1086/589937. S2CID   119197696.
73. "Will the Universe expand forever?". NASA. 24 January 2014. Retrieved 28 March 2021.
74. "Our flat universe". FermiLab/SLAC. 7 April 2015. Retrieved 28 March 2021.
75. Yoo, Marcus Y. (2011). "Unexpected connections". Engineering & Science. 74 (1): 30.
76. "Planck Publications: Planck 2015 Results". European Space Agency. February 2015. Retrieved 9 February 2015.
77. Percival, W. J.; et al. (2007). "Measuring the Baryon Acoustic Oscillation scale using the Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey". Monthly Notices of the Royal Astronomical Society . 381 (3): 1053–1066. arXiv: 0705.3323 . Bibcode:2007MNRAS.381.1053P. doi: 10.1111/j.1365-2966.2007.12268.x .
78. Komatsu, E.; et al. (2009). "Five-Year Wilkinson Microwave Anisotropy Probe Observations: Cosmological Interpretation". The Astrophysical Journal Supplement. 180 (2): 330–376. arXiv: 0803.0547 . Bibcode:2009ApJS..180..330K. doi:10.1088/0067-0049/180/2/330. S2CID   119290314.
79. Peacock, J.; et al. (2001). "A measurement of the cosmological mass density from clustering in the 2dF Galaxy Redshift Survey". Nature. 410 (6825): 169–173. arXiv: astro-ph/0103143 . Bibcode:2001Natur.410..169P. doi:10.1038/35065528. PMID   11242069. S2CID   1546652.
80. Viel, M.; Bolton, J. S.; Haehnelt, M. G. (2009). "Cosmological and astrophysical constraints from the Lyman α forest flux probability distribution function". Monthly Notices of the Royal Astronomical Society . 399 (1): L39 –L43. arXiv: 0907.2927 . Bibcode:2009MNRAS.399L..39V. doi: 10.1111/j.1745-3933.2009.00720.x . S2CID   12470622.
81. Silk, Joseph (2000). "IX". The Big Bang: Third Edition. Henry Holt and Company. ISBN   978-0-8050-7256-3.
82. Bambi, Cosimo; D. Dolgov, Alexandre (2016). Introduction to Particle Cosmology. UNITEXT for Physics. Springer Berlin, Heidelberg. p. 178. doi:10.1007/978-3-662-48078-6. ISBN   978-3-662-48078-6.
83. Vittorio, N.; J. Silk (1984). "Fine-scale anisotropy of the cosmic microwave background in a universe dominated by cold dark matter". Astrophysical Journal Letters. 285: L39 –L43. Bibcode:1984ApJ...285L..39V. doi:10.1086/184361.
84. Umemura, Masayuki; Satoru Ikeuchi (1985). "Formation of Subgalactic Objects within Two-Component Dark Matter". Astrophysical Journal. 299: 583–592. Bibcode:1985ApJ...299..583U. doi:10.1086/163726.
85. Bertone, G.; Merritt, D. (2005). "Dark Matter Dynamics and Indirect Detection". Modern Physics Letters A . 20 (14): 1021–1036. arXiv: astro-ph/0504422 . Bibcode:2005MPLA...20.1021B. doi:10.1142/S0217732305017391. S2CID   119405319.
86. Bansal, Saurabh; Barron, Jared; Curtin, David; Tsai, Yuhsin (16 October 2023). "Precision cosmological constraints on atomic dark matter". Journal of High Energy Physics. 2023 (10): 95. arXiv: 2212.02487 . Bibcode:2023JHEP...10..095B. doi:10.1007/JHEP10(2023)095. ISSN   1029-8479.
87. Bansal, Saurabh; Barron, Jared; Curtin, David; Tsai, Yuhsin (27 July 2023), "Precision Cosmological Constraints on Atomic Dark Matter", Journal of High Energy Physics, 2023 (10): 95, arXiv: 2212.02487 , Bibcode:2023JHEP...10..095B, doi:10.1007/JHEP10(2023)095, leading to a better fit than ΛCDM or ΛCDM + dark radiation
88. Sutter, Paul Sutter (7 June 2023). "Dark matter atoms may form shadowy galaxies with rapid star formation". Space.com. Retrieved 9 January 2024.
89. Armstrong, Isabella; et al. (2024). "Electromagnetic Signatures of Mirror Stars". The Astrophysical Journal. 965 (1): 42. arXiv: 2311.18086 . Bibcode:2024ApJ...965...42A. doi: 10.3847/1538-4357/ad283c .
90. VanDevender, J. Pace; VanDevender, Aaron P.; Sloan, T.; Swaim, Criss; Wilson, Peter; Schmitt, Robert G.; Zakirov, Rinat; Blum, Josh; Cross, James L.; McGinley, Niall (18 August 2017). "Detection of magnetized quark-nuggets, a candidate for dark matter". Scientific Reports. 7 (1): 8758. arXiv: 1708.07490 . Bibcode:2017NatSR...7.8758V. doi:10.1038/s41598-017-09087-3. ISSN   2045-2322. PMC   5562705 . PMID   28821866.
91. Dienes, Keith R.; Thomas, Brooks (24 April 2012). "Dynamical dark matter. I. Theoretical overview". Physical Review D. 85 (8): 083523. arXiv: 1106.4546 . Bibcode:2012PhRvD..85h3523D. doi:10.1103/PhysRevD.85.083523.
92. Hütsi, Gert; Raidal, Martti; Urrutia, Juan; Vaskonen, Ville; Veermäe, Hardi (2 February 2023). "Did JWST observe imprints of axion miniclusters or primordial black holes?". Physical Review D. 107 (4): 043502. arXiv: 2211.02651 . Bibcode:2023PhRvD.107d3502H. doi:10.1103/PhysRevD.107.043502. S2CID   253370365.
93. Espinosa, J. R.; Racco, D.; Riotto, A. (23 March 2018). "A Cosmological Signature of the Standard Model Higgs Vacuum Instability: Primordial Black Holes as Dark Matter". Physical Review Letters. 120 (12): 121301. arXiv: 1710.11196 . Bibcode:2018PhRvL.120l1301E. doi:10.1103/PhysRevLett.120.121301. PMID   29694085. S2CID   206309027.
94. Clesse, Sebastien; García-Bellido, Juan (2018). "Seven Hints for Primordial Black Hole Dark Matter". Physics of the Dark Universe. 22: 137–146. arXiv: 1711.10458 . Bibcode:2018PDU....22..137C. doi:10.1016/j.dark.2018.08.004. S2CID   54594536.
95. Lacki, Brian C.; Beacom, John F. (12 August 2010). "Primordial Black Holes as Dark Matter: Almost All or Almost Nothing". The Astrophysical Journal. 720 (1): L67 –L71. arXiv: 1003.3466 . Bibcode:2010ApJ...720L..67L. doi:10.1088/2041-8205/720/1/L67. ISSN   2041-8205. S2CID   118418220.
96. Kashlinsky, A. (23 May 2016). "LIGO gravitational wave detection, primordial black holes and the near-IR cosmic infrared background anisotropies". The Astrophysical Journal. 823 (2): L25. arXiv: 1605.04023 . Bibcode:2016ApJ...823L..25K. doi: 10.3847/2041-8205/823/2/L25 . ISSN   2041-8213. S2CID   118491150.
97. Frampton, Paul H.; Kawasaki, Masahiro; Takahashi, Fuminobu; Yanagida, Tsutomu T. (22 April 2010). "Primordial Black Holes as All Dark Matter". Journal of Cosmology and Astroparticle Physics. 2010 (4): 023. arXiv: 1001.2308 . Bibcode:2010JCAP...04..023F. doi:10.1088/1475-7516/2010/04/023. ISSN   1475-7516. S2CID   119256778.
98. Carneiro, S.; de Holanda, P.C.; Saa, A. (2021). "Neutrino primordial Planckian black holes". Physics Letters. B822: 136670. Bibcode:2021PhLB..82236670C. doi: 10.1016/j.physletb.2021.136670 . hdl: 20.500.12733/1987 . ISSN   0370-2693. S2CID   244196281.
99. "Baryonic Matter". COSMOS – The SAO Encyclopedia of Astronomy. Swinburne University of Technology . Retrieved 16 November 2022.
100. "Baryonic Matter". astronomy.swin.edu.au. Melbourne, Victoria, Australia: Swinburne University of Technology: Cosmos: The Swinburne Astronomy Online Encyclopedia. Retrieved 3 October 2023.
101. "MACHOs may be out of the running as a dark matter candidate". Astronomy.com. 2016. Retrieved 16 November 2022.
102. Weiss, Achim (2006). Big bang nucleosynthesis: Cooking up the first light elements. Vol. 2. Einstein Online. p. 1017. Archived from the original on 6 February 2013. Retrieved 1 June 2013.
103. Raine, D.; Thomas, T. (2001). An Introduction to the Science of Cosmology. IOP Publishing. p. 30. ISBN   978-0-7503-0405-4. OCLC   864166846.
104. Tisserand, P.; Le Guillou, L.; Afonso, C.; Albert, J.N.; Andersen, J.; Ansari, R.; et al. (2007). "Limits on the Macho content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds". Astronomy and Astrophysics. 469 (2): 387–404. arXiv: astro-ph/0607207 . Bibcode:2007A&A...469..387T. doi:10.1051/0004-6361:20066017. S2CID   15389106.
105. Graff, D. S.; Freese, K. (1996). "Analysis of a Hubble Space Telescope Search for Red Dwarfs: Limits on Baryonic Matter in the Galactic Halo". The Astrophysical Journal. 456 (1996): L49. arXiv: astro-ph/9507097 . Bibcode:1996ApJ...456L..49G. doi:10.1086/309850. S2CID   119417172.
106. Najita, J. R.; Tiede, G. P.; Carr, J. S. (2000). "From Stars to Superplanets: The Low-Mass Initial Mass Function in the Young Cluster IC 348". The Astrophysical Journal. 541 (2): 977–1003. arXiv: astro-ph/0005290 . Bibcode:2000ApJ...541..977N. doi:10.1086/309477. S2CID   55757804.
107. Wyrzykowski, L.; Skowron, J.; Kozlowski, S.; Udalski, A.; Szymanski, M.K.; Kubiak, M.; et al. (2011). "The OGLE View of Microlensing towards the Magellanic Clouds. IV. OGLE-III SMC Data and Final Conclusions on MACHOs". Monthly Notices of the Royal Astronomical Society. 416 (4): 2949–2961. arXiv: 1106.2925 . Bibcode:2011MNRAS.416.2949W. doi: 10.1111/j.1365-2966.2011.19243.x . S2CID   118660865.
108. Freese, Katherine; Fields, Brian; Graff, David (2000). "Death of stellar baryonic dark matter candidates". arXiv: astro-ph/0007444 .
109. Freese, Katherine; Fields, Brian; Graff, David (2003). "Death of Stellar Baryonic Dark Matter". The First Stars. ESO Astrophysics Symposia. pp. 4–6. arXiv: astro-ph/0002058 . Bibcode:2000fist.conf...18F. CiteSeerX   10.1.1.256.6883 . doi:10.1007/10719504_3. ISBN   978-3-540-67222-7. S2CID   119326375.
110. Canetti, L.; Drewes, M.; Shaposhnikov, M. (2012). "Matter and Antimatter in the Universe". New J. Phys. 14 (9): 095012. arXiv: 1204.4186 . Bibcode:2012NJPh...14i5012C. doi:10.1088/1367-2630/14/9/095012. S2CID   119233888.
111. Garrett, Katherine (2010). "Dark matter: A primer". Advances in Astronomy. 2011 (968283): 1–22. arXiv: 1006.2483 . Bibcode:2011AdAst2011E...8G. doi: 10.1155/2011/968283 .
112. Jungman, Gerard; Kamionkowski, Marc; Griest, Kim (1996). "Supersymmetric dark matter". Physics Reports. 267 (5–6): 195–373. arXiv: hep-ph/9506380 . Bibcode:1996PhR...267..195J. doi:10.1016/0370-1573(95)00058-5. S2CID   119067698.
113. "LHC discovery maims supersymmetry again". Discovery News.
114. Craig, Nathaniel (2013). "The State of Supersymmetry after Run I of the LHC". arXiv: 1309.0528 [hep-ph].
115. Fox, Patrick J.; Jung, Gabriel; Sorensen, Peter; Weiner, Neal (2014). "Dark matter in light of LUX". Physical Review D. 89 (10): 103526. arXiv: 1401.0216 . Bibcode:2014PhRvD..89j3526F. doi:10.1103/PhysRevD.89.103526.
116. Peccei, R. D. (2008). "The Strong CP Problem and Axions". In Kuster, Markus; Raffelt, Georg; Beltrán, Berta (eds.). Axions: Theory, Cosmology, and Experimental Searches. Lecture Notes in Physics. Vol. 741. pp. 3–17. arXiv: hep-ph/0607268 . doi:10.1007/978-3-540-73518-2_1. ISBN   978-3-540-73517-5. S2CID   119482294.
117. Preskill, J.; Wise, M.; Wilczek, F. (6 January 1983). "Cosmology of the invisible axion" (PDF). Physics Letters B. 120 (1–3): 127–132. Bibcode:1983PhLB..120..127P. CiteSeerX   10.1.1.147.8685 . doi:10.1016/0370-2693(83)90637-8.
118. Abbott, L.; Sikivie, P. (1983). "A cosmological bound on the invisible axion". Physics Letters B. 120 (1–3): 133–136. Bibcode:1983PhLB..120..133A. CiteSeerX   10.1.1.362.5088 . doi:10.1016/0370-2693(83)90638-X.
119. Dine, M.; Fischler, W. (1983). "The not-so-harmless axion". Physics Letters B. 120 (1–3): 137–141. Bibcode:1983PhLB..120..137D. doi:10.1016/0370-2693(83)90639-1.
120. di Luzio, L.; Nardi, E.; Giannotti, M.; Visinelli, L. (25 July 2020). "The landscape of QCD axion models". Physics Reports. 870: 1–117. arXiv: 2003.01100 . Bibcode:2020PhR...870....1D. doi:10.1016/j.physrep.2020.06.002. S2CID   211678181.
121. Graham, Peter W.; Scherlis, Adam (9 August 2018). "Stochastic axion scenario". Physical Review D. 98 (3): 035017. arXiv: 1805.07362 . Bibcode:2018PhRvD..98c5017G. doi:10.1103/PhysRevD.98.035017. S2CID   119432896.
122. Takahashi, Fuminobu; Yin, Wen; Guth, Alan H. (31 July 2018). "The QCD Axion Window and Low Scale Inflation". Physical Review D. 98 (1): 015042. arXiv: 1805.08763 . Bibcode:2018PhRvD..98a5042T. doi:10.1103/PhysRevD.98.015042. S2CID   54584447.
123. Marsh, David J.E. (2016). "Axion cosmology". Physics Reports. 643: 1–79. arXiv: 1510.07633 . Bibcode:2016PhR...643....1M. doi:10.1016/j.physrep.2016.06.005. S2CID   119264863.
124. "Dark matter's secret identity: WIMPs or axions?". Physics World. 25 June 2024.
125. Villanueva-Domingo, Pablo; Mena, Olga; Palomares-Ruiz, Sergio (2021). "A Brief Review on Primordial Black Holes as Dark Matter". Frontiers in Astronomy and Space Sciences. 8: 87. arXiv: 2103.12087 . Bibcode:2021FrASS...8...87V. doi: 10.3389/fspas.2021.681084 .
126. {{Carr, Bernard J.; Green, Anne M. (June 2024). "The History of Primordial Black Holes". arXiv: 2406.05736v1 [astro-ph.CO].
127. Cho, Adrian (9 February 2017). "Is dark matter made of black holes?". Science . doi:10.1126/science.aal0721.
128. "Black holes can't explain dark matter". Astronomy . 18 October 2018. Retrieved 7 January 2019– via astronomy.com.
129. Zumalacárregui, Miguel; Seljak, Uroš (1 October 2018). "Limits on Stellar-Mass Compact Objects as Dark Matter from Gravitational Lensing of Type Ia Supernovae". Physical Review Letters . 121 (14): 141101. arXiv: 1712.02240 . Bibcode:2018PhRvL.121n1101Z. doi:10.1103/PhysRevLett.121.141101. PMID   30339429. S2CID   53009603 . Retrieved 17 August 2023.
130. "Aging Voyager 1 spacecraft undermines idea that dark matter is tiny black holes". Science . 9 January 2019. Retrieved 10 January 2019– via sciencemag.org.
131. Hall, Shannon (5 February 2018). "There could be entire stars and planets made out of dark matter". New Scientist .
132. Buckley, Matthew R.; Difranzo, Anthony (2018). "Collapsed dark matter structures". Physical Review Letters . 120 (5): 051102. arXiv: 1707.03829 . Bibcode:2018PhRvL.120e1102B. doi:10.1103/PhysRevLett.120.051102. PMID   29481169. S2CID   3757868.
133. Niikura, Hiroko (1 April 2019). "Microlensing constraints on primordial black holes with Subaru/HSC Andromeda observations". Nature Astronomy . 3 (6): 524–534. arXiv: 1701.02151 . Bibcode:2019NatAs...3..524N. doi:10.1038/s41550-019-0723-1. S2CID   118986293.
134. Katz, Andrey; Kopp, Joachim; Sibiryakov, Sergey; Xue, Wei (5 December 2018). "Femtolensing by dark matter revisited". Journal of Cosmology and Astroparticle Physics. 2018 (12): 005. arXiv: 1807.11495 . Bibcode:2018JCAP...12..005K. doi:10.1088/1475-7516/2018/12/005. ISSN   1475-7516. S2CID   119215426.
135. Montero-Camacho, Paulo; Fang, Xiao; Vasquez, Gabriel; Silva, Makana; Hirata, Christopher M. (23 August 2019). "Revisiting constraints on asteroid-mass primordial black holes as dark matter candidates". Journal of Cosmology and Astroparticle Physics . 2019 (8): 031. arXiv: 1906.05950 . Bibcode:2019JCAP...08..031M. doi:10.1088/1475-7516/2019/08/031. ISSN   1475-7516. S2CID   189897766.
136. Buckley, Matthew R.; Difranzo, Anthony (1 February 2018). "Synopsis: A way to cool dark matter". Physical Review Letters . 120 (5): 051102. arXiv: 1707.03829 . Bibcode:2018PhRvL.120e1102B. doi:10.1103/PhysRevLett.120.051102. PMID   29481169. S2CID   3757868. Archived from the original on 26 October 2020.
137. "Are there any dark stars or dark galaxies made of dark matter?". Ask an Astronomer. curious.astro.cornell.edu. Cornell University. Archived from the original on 2 March 2015.
138. Siegel, Ethan (28 October 2016). "Why doesn't dark matter form black holes?". Forbes .
139. Gaitskell, Richard J. (2004). "Direct Detection of Dark Matter". Annual Review of Nuclear and Particle Science . 54: 315–359. Bibcode:2004ARNPS..54..315G. doi: 10.1146/annurev.nucl.54.070103.181244 . S2CID   11316578.
140. "Neutralino Dark Matter" . Retrieved 26 December 2011.Griest, Kim. "WIMPs and MACHOs" (PDF). Archived (PDF) from the original on 23 September 2006. Retrieved 26 December 2011.
141. Chadha-Day, Francesca; Ellis, John; Marsh, David J. E. (23 February 2022). "Axion dark matter: What is it and why now?". Science Advances. 8 (8): eabj3618. arXiv: 2105.01406 . Bibcode:2022SciA....8J3618C. doi:10.1126/sciadv.abj3618. PMC   8865781 . PMID   35196098.
142. Drees, M.; Gerbier, G. (2015). "Dark Matter" (PDF). Chin. Phys. C. 38: 090001. Archived (PDF) from the original on 22 July 2016.
143. Bernabei, R.; Belli, P.; Cappella, F.; Cerulli, R.; Dai, C. J.; d'Angelo, A.; et al. (2008). "First results from DAMA/LIBRA and the combined results with DAMA/NaI". Eur. Phys. J. C. 56 (3): 333–355. arXiv: 0804.2741 . Bibcode:2008EPJC...56..333B. doi:10.1140/epjc/s10052-008-0662-y. S2CID   14354488.
144. Drukier, A.; Freese, K.; Spergel, D. (1986). "Detecting Cold Dark Matter Candidates". Physical Review D. 33 (12): 3495–3508. Bibcode:1986PhRvD..33.3495D. doi:10.1103/PhysRevD.33.3495. PMID   9956575.
145. Davis, Jonathan H. (2015). "The past and future of light dark matter direct detection". Int. J. Mod. Phys. A. 30 (15): 1530038. arXiv: 1506.03924 . Bibcode:2015IJMPA..3030038D. doi:10.1142/S0217751X15300380. S2CID   119269304.
146. Aprile, E. (2017). "Search for electronic recoil event rate modulation with 4 years of XENON100 data". Phys. Rev. Lett. 118 (10): 101101. arXiv: 1701.00769 . Bibcode:2017PhRvL.118j1101A. doi:10.1103/PhysRevLett.118.101101. PMID   28339273. S2CID   206287497.
147. Stonebraker, Alan (3 January 2014). "Synopsis: Dark-Matter Wind Sways through the Seasons". Physics – Synopses. American Physical Society. doi:10.1103/PhysRevLett.112.011301.
148. Lee, Samuel K.; Lisanti, Mariangela; Peter, Annika H.G.; Safdi, Benjamin R. (3 January 2014). "Effect of Gravitational Focusing on Annual Modulation in Dark-Matter Direct-Detection Experiments". Phys. Rev. Lett. 112 (1): 011301 [5 pages]. arXiv: 1308.1953 . Bibcode:2014PhRvL.112a1301L. doi:10.1103/PhysRevLett.112.011301. PMID   24483881. S2CID   34109648.
149. The Dark Matter Group. "An Introduction to Dark Matter". Dark Matter Research. Sheffield: University of Sheffield. Archived from the original on 29 July 2020. Retrieved 7 January 2014.
150. "Blowing in the Wind". Kavli News. Sheffield: Kavli Foundation. Archived from the original on 7 October 2020. Retrieved 7 January 2014. Scientists at Kavli MIT are working on ... a tool to track the movement of dark matter.
151. "Dark matter even darker than once thought". Space Telescope Science Institute. Retrieved 16 June 2015.
152. Bertone, Gianfranco (2010). "Dark Matter at the Centers of Galaxies". Particle Dark Matter: Observations, Models and Searches. Cambridge University Press. pp. 83–104. arXiv: 1001.3706 . Bibcode:2010arXiv1001.3706M. ISBN   978-0-521-76368-4.
153. Ellis, J.; Flores, R. A.; Freese, K.; Ritz, S.; Seckel, D.; Silk, J. (1988). "Cosmic ray constraints on the annihilations of relic particles in the galactic halo" (PDF). Physics Letters B. 214 (3): 403–412. Bibcode:1988PhLB..214..403E. doi:10.1016/0370-2693(88)91385-8. Archived (PDF) from the original on 28 July 2018.
154. Freese, K. (1986). "Can Scalar Neutrinos or Massive Dirac Neutrinos be the Missing Mass?". Physics Letters B. 167 (3): 295–300. Bibcode:1986PhLB..167..295F. doi:10.1016/0370-2693(86)90349-7.
155. Sokol, Joshua; et al. (20 February 2016). "Surfing gravity's waves". New Scientist. No. 3061.
156. "Did gravitational wave detector find dark matter?". Johns Hopkins University. 15 June 2016. Retrieved 20 June 2015. While their existence has not been established with certainty, primordial black holes have in the past been suggested as a possible solution to the dark matter mystery. Because there is so little evidence of them, though, the primordial black hole–dark matter hypothesis has not gained a large following among scientists. The LIGO findings, however, raise the prospect anew, especially as the objects detected in that experiment conform to the mass predicted for dark matter. Predictions made by scientists in the past held conditions at the birth of the universe would produce many of these primordial black holes distributed approximately evenly in the universe, clustering in halos around galaxies. All this would make them good candidates for dark matter.
157. Bird, Simeon; Cholis, Illian (2016). "Did LIGO detect dark matter?". Physical Review Letters. 116 (20): 201301. arXiv: 1603.00464 . Bibcode:2016PhRvL.116t1301B. doi:10.1103/PhysRevLett.116.201301. PMID   27258861. S2CID   23710177.
158. Stecker, F. W.; Hunter, S.; Kniffen, D. (2008). "The likely cause of the EGRET GeV anomaly and its implications". Astroparticle Physics. 29 (1): 25–29. arXiv: 0705.4311 . Bibcode:2008APh....29...25S. doi:10.1016/j.astropartphys.2007.11.002. S2CID   15107441.
159. Atwood, W.B.; Abdo, A.A.; Ackermann, M.; Althouse, W.; Anderson, B.; Axelsson, M.; et al. (2009). "The large area telescope on the Fermi Gamma-ray Space Telescope Mission". Astrophysical Journal. 697 (2): 1071–1102. arXiv: 0902.1089 . Bibcode:2009ApJ...697.1071A. doi:10.1088/0004-637X/697/2/1071. S2CID   26361978.
160. "Physicists revive hunt for dark matter in the heart of the Milky Way". www.science.org. 12 November 2019. Retrieved 9 May 2023.
161. Weniger, Christoph (2012). "A tentative gamma-ray line from dark matter annihilation at the Fermi Large Area Telescope". Journal of Cosmology and Astroparticle Physics. 2012 (8): 7. arXiv: 1204.2797 . Bibcode:2012JCAP...08..007W. doi:10.1088/1475-7516/2012/08/007. S2CID   119229841.
162. Cartlidge, Edwin (24 April 2012). "Gamma rays hint at dark matter". Institute of Physics. Retrieved 23 April 2013.
163. Albert, J.; Aliu, E.; Anderhub, H.; Antoranz, P.; Backes, M.; Baixeras, C.; et al. (2008). "Upper Limit for γ-Ray Emission above 140 GeV from the Dwarf Spheroidal Galaxy Draco". The Astrophysical Journal. 679 (1): 428–431. arXiv: 0711.2574 . Bibcode:2008ApJ...679..428A. doi:10.1086/529135. S2CID   15324383.
164. Aleksić, J.; Antonelli, L.A.; Antoranz, P.; Backes, M.; Baixeras, C.; Balestra, S.; et al. (2010). "Magic Gamma-Ray Telescope observation of the Perseus Cluster of galaxies: Implications for cosmic rays, dark matter, and NGC 1275". The Astrophysical Journal. 710 (1): 634–647. arXiv: 0909.3267 . Bibcode:2010ApJ...710..634A. doi:10.1088/0004-637X/710/1/634. S2CID   53120203.
165. Adriani, O.; Barbarino, G.C.; Bazilevskaya, G.A.; Bellotti, R.; Boezio, M.; Bogomolov, E.A.; et al. (2009). "An anomalous positron abundance in cosmic rays with energies 1.5–100 GeV". Nature. 458 (7238): 607–609. arXiv: 0810.4995 . Bibcode:2009Natur.458..607A. doi:10.1038/nature07942. PMID   19340076. S2CID   11675154.
166. Aguilar, M.; et al. (AMS Collaboration) (3 April 2013). "First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–350 GeV". Physical Review Letters . 110 (14): 141102. Bibcode:2013PhRvL.110n1102A. doi: 10.1103/PhysRevLett.110.141102 . hdl: 1721.1/81241 . PMID   25166975.
167. AMS Collaboration (3 April 2013). "First Result from the Alpha Magnetic Spectrometer Experiment". Archived from the original on 8 April 2013. Retrieved 3 April 2013.
168. Heilprin, John; Borenstein, Seth (3 April 2013). "Scientists find hint of dark matter from cosmos". Associated Press. Retrieved 3 April 2013.
169. Amos, Jonathan (3 April 2013). "Alpha Magnetic Spectrometer zeroes in on dark matter". BBC. Retrieved 3 April 2013.
170. Perrotto, Trent J.; Byerly, Josh (2 April 2013). "NASA TV Briefing Discusses Alpha Magnetic Spectrometer Results". NASA. Retrieved 3 April 2013.
171. Overbye, Dennis (3 April 2013). "New Clues to the Mystery of Dark Matter". The New York Times. Archived from the original on 1 January 2022. Retrieved 3 April 2013.
172. Kane, G.; Watson, S. (2008). "Dark Matter and LHC:. what is the Connection?". Modern Physics Letters A. 23 (26): 2103–2123. arXiv: 0807.2244 . Bibcode:2008MPLA...23.2103K. doi:10.1142/S0217732308028314. S2CID   119286980.
173. Fox, P. J.; Harnik, R.; Kopp, J.; Tsai, Y. (2011). "LEP Shines Light on Dark Matter". Phys. Rev. D. 84 (1): 014028. arXiv: 1103.0240 . Bibcode:2011PhRvD..84a4028F. doi:10.1103/PhysRevD.84.014028. S2CID   119226535.
174. Peebles, P. J. E. (December 2004). "Probing General Relativity on the Scales of Cosmology". General Relativity and Gravitation. pp. 106–117. arXiv: astro-ph/0410284 . Bibcode:2005grg..conf..106P. doi:10.1142/9789812701688_0010. ISBN   978-981-256-424-5. S2CID   1700265.
175. For a review, see: Kroupa, Pavel; et al. (December 2012). "The failures of the Standard Model of Cosmology require a new paradigm". International Journal of Modern Physics D. 21 (4): 1230003. arXiv: 1301.3907 . Bibcode:2012IJMPD..2130003K. doi:10.1142/S0218271812300030. S2CID   118461811.
176. For a review, see: Salvatore Capozziello; Mariafelicia De Laurentis (October 2012). "The dark matter problem from f(R) gravity viewpoint". Annalen der Physik. 524 (9–10): 545. Bibcode:2012AnP...524..545C. doi: 10.1002/andp.201200109 .
177. "Bringing balance to the Universe". University of Oxford. 5 December 2018.
178. "Bringing balance to the universe: New theory could explain missing 95 percent of the cosmos". Phys.Org.
179. Farnes, J. S. (2018). "A Unifying Theory of Dark Energy and Dark Matter: Negative Masses and Matter Creation within a Modified ΛCDM Framework". Astronomy & Astrophysics. 620: A92. arXiv: 1712.07962 . Bibcode:2018A&A...620A..92F. doi:10.1051/0004-6361/201832898. S2CID   53600834.
180. "New theory of gravity might explain dark matter". phys.org. November 2016.
181. Mannheim, Phillip D. (April 2006). "Alternatives to dark matter and dark energy". Progress in Particle and Nuclear Physics. 56 (2): 340–445. arXiv: astro-ph/0505266 . Bibcode:2006PrPNP..56..340M. doi:10.1016/j.ppnp.2005.08.001. S2CID   14024934.
182. Joyce, Austin; et al. (March 2015). "Beyond the Cosmological Standard Model". Physics Reports. 568: 1–98. arXiv: 1407.0059 . Bibcode:2015PhR...568....1J. doi:10.1016/j.physrep.2014.12.002. S2CID   119187526.
183. "Verlinde's new theory of gravity passes first test". 16 December 2016.
184. Brouwer, Margot M.; et al. (April 2017). "First test of Verlinde's theory of Emergent Gravity using Weak Gravitational Lensing measurements". Monthly Notices of the Royal Astronomical Society . 466 (3): 2547–2559. arXiv: 1612.03034 . Bibcode:2017MNRAS.466.2547B. doi: 10.1093/mnras/stw3192 . S2CID   18916375.
185. "First test of rival to Einstein's gravity kills off dark matter". 15 December 2016. Retrieved 20 February 2017.
186. "Unique prediction of 'modified gravity' challenges dark matter". ScienceDaily. 16 December 2020. Retrieved 14 January 2021.
187. Chae, Kyu-Hyun; et al. (20 November 2020). "Testing the Strong Equivalence Principle: Detection of the External Field Effect in Rotationally Supported Galaxies". Astrophysical Journal . 904 (1): 51. arXiv: 2009.11525 . Bibcode:2020ApJ...904...51C. doi: 10.3847/1538-4357/abbb96 . S2CID   221879077.
188. Cramer, John G. (1 July 2003). "LSST – the dark matter telescope". Analog Science Fiction and Fact . 123 (7/8): 96. ISSN   1059-2113. ProQuest   215342129. (Registration required)
189. Ahern, James (16 February 2003). "Space travel: Outdated goal". The Record . p. O 02. ProQuest   425551312. (Registration required)
190. Halden, Grace (Spring 2015). "Incandescent: Light bulbs and conspiracies". Dandelion: Postgraduate Arts Journal and Research Network. Vol. 5, no. 2. doi: 10.16995/ddl.318 .
191. Gribbin, Mary; Gribbin, John (2007). The Science of Philip Pullman's His Dark Materials. Random House Children's Books. pp. 15–30. ISBN   978-0-375-83146-1.
192. Fraknoi, Andrew (2019). "Science fiction for scientists". Nature Physics . 12 (9): 819–820. doi:10.1038/nphys3873. S2CID   125376175.
193. Frank, Adam (9 February 2017). "Dark matter is in our DNA". Nautilus Quarterly . Retrieved 11 December 2022.
194. "First 3D map of the Universe's dark matter scaffolding". www.esa.int. Retrieved 23 November 2021.
195. Massey, Richard; Rhodes, Jason; Ellis, Richard; Scoville, Nick; Leauthaud, Alexie; Finoguenov, Alexis; Capak, Peter; Bacon, David; Aussel, Hervé; Kneib, Jean-Paul; Koekemoer, Anton (January 2007). "Dark matter maps reveal cosmic scaffolding". Nature. 445 (7125): 286–290. arXiv: astro-ph/0701594 . Bibcode:2007Natur.445..286M. doi:10.1038/nature05497. ISSN   1476-4687. PMID   17206154. S2CID   4429955.
196. "News CFHT - Astronomers reach new frontiers of dark matter". www.cfht.hawaii.edu. Retrieved 26 November 2021.
197. Heymans, Catherine; Van Waerbeke, Ludovic; Miller, Lance; Erben, Thomas; Hildebrandt, Hendrik; Hoekstra, Henk; Kitching, Thomas D.; Mellier, Yannick; Simon, Patrick; Bonnett, Christopher; Coupon, Jean (21 November 2012). "CFHTLenS: the Canada–France–Hawaii Telescope Lensing Survey: CFHTLenS". Monthly Notices of the Royal Astronomical Society. 427 (1): 146–166. arXiv: 1210.0032 . doi: 10.1111/j.1365-2966.2012.21952.x . S2CID   24731530.
198. "KiDS". kids.strw.leidenuniv.nl. Retrieved 27 November 2021.
199. Kuijken, Konrad; Heymans, Catherine; Hildebrandt, Hendrik; Nakajima, Reiko; Erben, Thomas; Jong, Jelte T. A.; Viola, Massimo; Choi, Ami; Hoekstra, Henk; Miller, Lance; van Uitert, Edo (10 October 2015). "Gravitational lensing analysis of the Kilo-Degree Survey". Monthly Notices of the Royal Astronomical Society. 454 (4): 3500–3532. arXiv: 1507.00738 . doi: 10.1093/mnras/stv2140 . ISSN   0035-8711.
200. University, Carnegie Mellon (26 September 2018). "Hyper Suprime-Cam Survey Maps Dark Matter in the Universe - News - Carnegie Mellon University". www.cmu.edu. Archived from the original on 7 September 2020.
201. Hikage, Chiaki; Oguri, Masamune; Hamana, Takashi; More, Surhud; Mandelbaum, Rachel; Takada, Masahiro; Köhlinger, Fabian; Miyatake, Hironao; Nishizawa, Atsushi J; Aihara, Hiroaki; Armstrong, Robert (1 April 2019). "Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data". Publications of the Astronomical Society of Japan. 71 (2): 43. arXiv: 1809.09148 . doi:10.1093/pasj/psz010. ISSN   0004-6264.
202. Jeffrey, N; Gatti, M; Chang, C; Whiteway, L; Demirbozan, U; Kovacs, A; Pollina, G; Bacon, D; Hamaus, N; Kacprzak, T; Lahav, O (25 June 2021). "Dark Energy Survey Year 3 results: Curved-sky weak lensing mass map reconstruction". Monthly Notices of the Royal Astronomical Society. 505 (3): 4626–4645. arXiv: 2105.13539 . doi: 10.1093/mnras/stab1495 . ISSN   0035-8711.
203. Castelvecchi, Davide (28 May 2021). "The most detailed 3D map of the Universe ever made". Nature: d41586–021–01466-1. doi:10.1038/d41586-021-01466-1. ISSN   0028-0836. PMID   34050347. S2CID   235242965.

Further reading

• Bartusiak, Marcia (1993). Through a Universe Darkly: A cosmic tale of ancient ethers, dark matter, and the fate of the universe (1 ed.). New York: HarperCollins. ISBN   978-0-06-018310-3.
• Freeman, Ken; MacNamara, Geoff (2006). In Search of Dark Matter. Springer-Praxis Books in Popular Astronomy. Berlin, Springer, Chichester: Springer/Praxis. ISBN   978-0-387-27616-8.
• Sanders, Robert H. (2010). The Dark Matter Problem: A historical perspective. Cambridge, New York: Cambridge University Press. ISBN   978-0-511-77357-0.
• Overduin, James M.; Wesson, Paul S. (2003). Dark Sky, Dark Matter. Series in Astronomy and Astrophysics. Bristol: Institute of Physics. ISBN   978-0-7503-0684-3.
• Krauss, Lawrence M. (1989). The Fifth Essence: The search for dark matter in the universe. New York: Basic Books. ISBN   978-0-465-02375-2.
• Bertone, Gianfranco (2010). Particle Dark Matter: Observations, models and searches. Cambridge: Cambridge University Press. ISBN   978-0-521-76368-4.
• Panek, Richard (2011). The 4 Percent Universe: Dark matter, dark energy, and the race to discover the rest of reality. Boston: Houghton Mifflin Harcourt. ISBN   978-0-618-98244-8. (Recommended on BookAuthrority site) ^[1] )
• Weiss, Rainer, (July/August 2023) "The Dark Universe Comes into Focus" Scientific American , vol. 329, no. 1, pp. 7–8.

External links

• Tremaine, Scott. Lecture on dark matter (Video). IAS.
• Gray, Meghan; Merrifield, Mike; Copeland, Ed (2010). Haran, Brady (ed.). "Dark Matter". Sixty Symbols. University of Nottingham.

1. "The Best Dark Matter Books of All Time". BookAuthority. Retrieved 28 December 2024.