Non baryonic matter
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Non-Baryonic Dark Matter: Observational Evidence and Detection Methods
Introduction to Non-Baryonic Dark Matter
Non-baryonic dark matter is a critical component of the universe's mass-energy content, distinct from ordinary (baryonic) matter such as protons, neutrons, and electrons. Observational evidence suggests that non-baryonic dark matter constitutes a significant portion of the universe's total mass density, contributing between 20% and 40% of the critical mass density required to make the universe geometrically flat on large scales Bergström2000Kitano2004. This type of dark matter is essential to explain various cosmological phenomena that cannot be accounted for by baryonic matter alone Gondolo2005Del Popolo2013.
The Need for Non-Baryonic Dark Matter
Recent advances in cosmology have provided a consistent picture of the universe's matter and energy content. Observations indicate that less than 2% of the universe's matter is luminous, and no more than 20% is made of ordinary matter. The remaining 80% or more is non-baryonic dark matter, which is crucial for understanding the universe's structure and evolution Gondolo2005Carr2000. This non-baryonic component is necessary to explain the observed gravitational effects on galaxies and galaxy clusters, which cannot be attributed solely to visible matter Bergström2000Bergström2000.
Popular Candidates for Non-Baryonic Dark Matter
Several theoretically favored candidates for non-baryonic dark matter have been proposed, including:
- Axions: Hypothetical particles that could solve the strong CP problem in quantum chromodynamics and contribute to dark matter Bergström2000Usón2000.
- Supersymmetric Particles: Particles predicted by supersymmetry theories, such as neutralinos, which are considered strong candidates for cold dark matter Bergström2000Kitano2004.
- Massive Neutrinos: Although less significant, massive neutrinos are also considered potential contributors to non-baryonic dark matter Bergström2000Del Popolo2013.
Detection Methods for Non-Baryonic Dark Matter
Direct Detection
Direct detection methods aim to observe dark matter particles interacting with ordinary matter. Experiments are designed to detect the rare collisions between dark matter particles and atomic nuclei. Current experiments are reaching the sensitivity required to discover or rule out some dark matter candidates, with significant improvements planned for the future Bergström2000Usón2000.
Indirect Detection
Indirect detection methods involve searching for the byproducts of dark matter interactions, such as high-energy neutrinos, gamma rays, and positrons. These methods can provide complementary evidence for the existence of dark matter and help identify its properties Gondolo2005Carr2000.
Conclusion
Non-baryonic dark matter is a fundamental component of the universe, essential for explaining various cosmological observations. While several candidates have been proposed, including axions, supersymmetric particles, and massive neutrinos, ongoing and future experiments aim to detect these elusive particles directly or indirectly. Understanding non-baryonic dark matter remains one of the most significant challenges in modern cosmology, with the potential to unlock new insights into the universe's fundamental nature.
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