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Limit on primordial small-scale magnetic fields from cosmic microwave background distortions
1Max-Planck-Institut fur Astrophysik, 85748 Garching bei Munchen, Germany.
Physical Review Letters
|September 16, 2000
Summary
Primordial magnetic fields dissipate before cosmic recombination, creating observable distortions in the cosmic microwave background. This finding sets new, strong limits on small-scale magnetic fields.
Area of Science:
- Cosmology
- Astrophysics
- Particle Physics
Background:
- Primordial magnetic fields may decay due to the viscosity of the baryon-photon fluid before cosmic recombination.
- This dissipation process could leave detectable imprints on the cosmic microwave background (CMB).
Purpose of the Study:
- To investigate the potential for dissipation of spatially varying primordial magnetic fields.
- To determine if this dissipation leads to observable distortions in the CMB spectrum, specifically chemical potential (μ) and Compton y distortions.
- To establish constraints on the strength of small-scale primordial magnetic fields.
Main Methods:
- Theoretical modeling of magnetic field dissipation in the early universe.
- Analysis of the effects of dissipation on the baryon-photon fluid.
- Comparison of theoretical predictions with observational data from the Far Infrared Absolute Spectrophotometer (FIRAS) instrument.
Main Results:
- Spatially varying primordial magnetic fields can be efficiently dissipated by the baryon-photon fluid.
- This dissipation generates observable chemical potential (μ) and Compton y distortions in the CMB spectrum.
- Current FIRAS upper limits on μ and y constrain primordial magnetic fields.
Conclusions:
- Primordial magnetic fields with strengths B0 < 3x10^-8 G (present-day scaled) and comoving coherence lengths between approximately 400 pc and 0.6 Mpc are constrained.
- These represent the most stringent upper limits to date on small-scale primordial magnetic fields.
- The study highlights the importance of CMB distortions as probes of early universe physics.
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