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In astronomy and cosmology, baryonic dark matter is dark matter composed of baryons. Only a small proportion of the dark matter in the universe is likely to be baryonic.

Characteristics

As "dark matter", baryonic dark matter is undetectable by its emitted radiation, but its presence can be inferred from gravitational effects on visible matter. This form of dark matter is composed of "baryons", heavy subatomic particles such as protons and neutrons and combinations of these, including non-emitting ordinary atoms.
Presence

Baryonic dark matter may occur in non-luminous gas or in Massive Astrophysical Compact Halo Objects (MACHOs) - condensed objects such as black holes, neutron stars, white dwarfs, very faint stars, or non-luminous objects like planets and brown dwarfs.
Estimates of quantity

The total amount of baryonic dark matter can be inferred from models of Big Bang nucleosynthesis, and observations of the cosmic microwave background. Both indicate that the amount of baryonic dark matter is much smaller than the total amount of dark matter.
Big Bang nucleosynthesis

From the perspective of Big Bang nucleosynthesis, a larger amount of ordinary (baryonic) matter implies a denser early universe, more efficient conversion of matter to helium-4, and less unburned deuterium remaining. If all of the dark matter in the universe were baryonic, then there would be much less deuterium in the universe than is observed. This could be resolved if more deuterium were somehow generated, but large efforts in the 1970s failed to identify plausible mechanisms for this to occur. For instance, MACHOs, which include, for example, brown dwarfs (bodies of hydrogen and helium with masses less than 0.08 M☉ or 1.6×1029 kg), never begin nuclear fusion of hydrogen, but they do burn deuterium. Other possibilities that were examined include "Jupiters", which are similar to brown dwarfs but have masses ∼ {\displaystyle \sim } \sim 0.001 M☉ (2×1027 kg) and do not burn anything, and white dwarfs.[1][2]
See also

Particle chauvinism

References

G. Jungman; M. Kamionkowski & K. Griest (1996). "Supersymmetric dark matter". Physics Reports. 267: 195. arXiv:hep-ph/9506380. Bibcode:1996PhR...267..195J. doi:10.1016/0370-1573(95)00058-5.

M. S. Turner (1999). "Cosmological parameters". AIP Conference Proceedings. arXiv:astro-ph/9904051. Bibcode:1999AIPC..478..113T. doi:10.1063/1.59381.

vte

Dark matter
Forms of
dark matter

Baryonic dark matter Cold dark matter Hot dark matter Light dark matter Mixed dark matter Warm dark matter Self-interacting dark matter Scalar field dark matter Primordial black holes


Hypothetical particles

Axino Axion Dark photon Holeum LSP Minicharged particle Neutralino Sterile neutrino SIMP WIMP

Theories
and objects

Cuspy halo problem Dark fluid Dark galaxy Dark globular cluster Dark matter halo Dark radiation Dark star Dwarf galaxy problem Halo mass function Mass dimension one fermions Massive compact halo object Mirror matter Navarro–Frenk–White profile Scalar field dark matter

Search
experiments
Direct
detection

ADMX ANAIS ArDM CDEX CDMS CLEAN CoGeNT COSINE COUPP CRESST CUORE D3 DAMA/LIBRA DAMA/NaI DAMIC DarkSide DARWIN DEAP DM-Ice DMTPC DRIFT EDELWEISS EURECA KIMS LUX LZ MACRO MIMAC NAIAD NEWAGE NEWS-G PandaX PICASSO PICO ROSEBUD SABRE SIMPLE TREX-DM UKDMC WARP XENON XMASS ZEPLIN

Indirect
detection

AMS-02 ANTARES ATIC CALET CAST DAMPE Fermi HAWC HESS IceCube MAGIC MOA OGLE PAMELA VERITAS

Other projects

MultiDark PVLAS

Potential dark galaxies

HE0450-2958 HVC 127-41-330 Smith's Cloud VIRGOHI21

Related

Antimatter Dark energy Exotic matter Galaxy formation and evolution Illustris project Imaginary mass Negative mass UniverseMachine

Physics Encyclopedia

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Index

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