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Small-scale power spectrum of cold dark matter
- Source :
- Physical Review D. 71
- Publication Year :
- 2005
- Publisher :
- American Physical Society (APS), 2005.
-
Abstract
- One of the best motivated hypotheses in cosmology states that most of the matter in the universe is in the form of weakly-interacting massive particles that decoupled early in the history of the universe and cooled adiabatically to an extremely low temperature. Nevertheless, the finite temperature and horizon scales at which these particles decoupled imprint generic signatures on their small scales density fluctuations. We show that the previously recognized cut-off in the fluctuation power-spectrum due to free-streaming of particles at the thermal speed of decoupling, is supplemented by acoustic oscillations owing to the initial coupling between the cold dark matter (CDM) and the radiation field. The power-spectrum oscillations appear on the scale of the horizon at thermal decoupling which corresponds to a mass scale of \~10^{-4}*(T_d/10MeV)^{-3} solar masses for a CDM decoupling temperature T_d. The suppression of the power-spectrum on smaller scales by the acoustic oscillations is physically independent from the free-streaming effect, although the two cut-off scales are coincidentally comparable for T_d~10MeV and a particle mass of M~100GeV. The initial conditions for recent numerical simulations of the earliest and smallest objects to have formed in the universe, need to be modified accordingly. The smallest dark matter clumps may be detectable through gamma-ray production from particle annihilation, through fluctuations in the event rate of direct detection experiments, or through their tidal gravitational effect on wide orbits of objects near the outer edge of the solar system.<br />Physical Review D, in press
- Subjects :
- Physics
Nuclear and High Energy Physics
Cold dark matter
010308 nuclear & particles physics
media_common.quotation_subject
Horizon
Astrophysics (astro-ph)
Dark matter
FOS: Physical sciences
Spectral density
Astrophysics
Decoupling (cosmology)
01 natural sciences
Universe
Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Phenomenology (hep-ph)
13. Climate action
0103 physical sciences
Baryon acoustic oscillations
010303 astronomy & astrophysics
media_common
Subjects
Details
- ISSN :
- 15502368 and 15507998
- Volume :
- 71
- Database :
- OpenAIRE
- Journal :
- Physical Review D
- Accession number :
- edsair.doi.dedup.....00d016eecbe001d8288c87ec1bb7c5b0