Does dark matter emit radiation
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Does Dark Matter Emit Radiation?
Introduction to Dark Matter and Radiation
Dark matter, a mysterious and invisible component of the universe, does not interact with electromagnetic forces, making it undetectable through conventional means like light or radiation. However, the question of whether dark matter can emit any form of radiation remains a topic of significant scientific inquiry.
Exotic Compact Objects and Radiation Suppression
Certain theoretical models propose that dark matter could be composed of exotic compact objects (ECOs) such as wormholes, fuzzballs, and gravastars. These objects are expected to emit significantly less radiation compared to black holes. If primordial curvature fluctuations collapse into these ECOs instead of black holes, they would evaporate much slower, potentially constituting all dark matter with masses below (10^{-16} M_{\odot})1. This suggests that if dark matter is made up of such ECOs, its radiation emission would be minimal.
Conversion of Dark Matter to Radiation
Another perspective considers the possibility that dark matter could convert into a non-interacting form of radiation at any point during cosmological evolution. This scenario, which includes dark matter decaying or annihilating into radiation, is strongly constrained by observations of the cosmic microwave background. However, there is some evidence suggesting that large-scale structure observations might prefer a late-time conversion of dark matter to radiation, which could help address certain cosmological tensions2.
Non-Abelian Dark Matter and Dark Radiation
In some models, dark matter is charged with respect to "dark" gluons from a new non-Abelian gauge theory. These gluons constitute self-interacting dark radiation. This model predicts distinctive experimental signatures and has significant cosmological implications3.
Signatures in Neutrino and Dark Matter Detectors
There is also the possibility that dark radiation, which could be a relativistic or semi-relativistic component of dark matter, interacts non-gravitationally with standard model particles. If such dark radiation is produced by the late decay of an unstable particle, it could leave detectable imprints in experiments designed to search for weakly interacting particles, such as dark matter and underground neutrino detectors. These interactions could create a "neutrino floor" for dark matter detection, closer to current bounds than expected from standard neutrino sources4.
Nonthermal Production of Dark Radiation
Dark matter might be coupled to dark radiation, which mediates forces between dark sector particles. Cosmological constraints favor dark radiation that is colder than standard model radiation. Models involving asymmetric reheating from late decays of long-lived particles can populate a sufficiently cold dark sector while generating baryon and dark matter asymmetries. This approach helps avoid overproduction of dark radiation due to non-negligible dark-visible couplings5.
Dark Matter Annihilation and Gamma-Ray Emission
If dark matter consists of weakly self-interacting particles, they may self-annihilate and emit gamma-rays. High-resolution numerical simulations suggest that the annihilation flux from the Milky Way's central regions and its halo substructures might be detectable. However, these estimates are uncertain and depend heavily on the structure of the densest regions. Despite these uncertainties, the annihilation flux could be within the detection capabilities of next-generation gamma-ray detectors6.
Conclusion
In summary, while dark matter itself does not emit radiation in the conventional sense, various theoretical models and scenarios suggest that it could produce detectable radiation under specific conditions. These include the presence of exotic compact objects, conversion to non-interacting radiation, interactions with dark gluons, and self-annihilation processes. Ongoing and future experiments in neutrino and dark matter detection, as well as gamma-ray astronomy, are crucial for exploring these possibilities and enhancing our understanding of dark matter's nature and behavior.
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Most relevant research papers on this topic
Light primordial exotic compact objects as all dark matter
Light primordial exotic compact objects could constitute all dark matter with masses below M1016 M, opening up a large new parameter space for light primordial dark matter.
Converting nonrelativistic dark matter to radiation
Converting nonrelativistic dark matter to radiation is a viable scenario, and observations of the cosmic microwave background strongly constrain this scenario for all conversion times after big bang nucleosynthesis.
Highly CitedNon-Abelian dark matter and dark radiation
This paper explores a new non-Abelian gauge theory that suggests dark matter is charged with respect to 'dark' gluons, leading to self-interacting dark radiation and unique experimental signatures.
Highly CitedSignatures of Dark Radiation in Neutrino and Dark Matter Detectors
Dark radiation with nongravitational interactions can leave detectable imprints in sensitive neutrino and dark matter detectors, potentially providing competitive constraints on different forms of dark radiation.
Nonthermal production of dark radiation and dark matter
A model of asymmetric reheating of the visible and dark sectors from late decays of long-lived particles can populate a cold dark sector while generating baryon and dark matter asymmetries through out-of-equilibrium decay.
Dark matter annihilation in the halo of the Milky Way
High-resolution numerical simulations suggest that dark matter annihilation in the Milky Way's halo may be detectable, regardless of uncertainties about densest regions.
Highly CitedDark matter and gravitational waves from a dark big bang
The Dark Big Bang scenario, which creates dark matter and potentially dark radiation, is consistent with structure formation and the CMB constraints, and may lead to striking gravity wave signatures.
Dark matter and dark radiation
Dark electromagnetism, a new long-range U(1) gauge field, could potentially explain the structure and dynamics of dark matter in the universe.
Highly CitedDark matter and background light
Dark matter is most likely to be weakly interacting massive particles (WIMPs) or higher-dimensional sources, affecting the night sky's light patterns.
Highly CitedDark radiation and dark matter in large volume compactifications
Dark radiation and dark matter are generated from the decay of the overall volume modulus in large volume compactifications, with the axionic superpartner of the modulus playing a key role in both sequestered and non-sequestered cases.
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