The CMBR spectrum: new upper limits for the distortion parameters y and mu
| Autor: | Elia S. Battistelli, C. Macculi, V. Fulcoli |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2000 |
| Předmět: |
Physics
Diffraction media_common.quotation_subject Cosmic microwave background Astronomy and Astrophysics Astrophysics Function (mathematics) Computational physics Space and Planetary Science Sky Distortion Emissivity Waveguide (acoustics) Instrumentation: detectors COBE-FIRAS Cosmology: theory Distortion parameters Black-body radiation Instrumentation media_common |
| Popis: | The CMBR Spectrum has been measured by the COBE-FIRAS experiment. Upper limits only have been found for distortion parameters y and μ : y up =1.5×10 −5 and μ up =9×10 −5 at 95% of confidence. FIRAS made differential measurements between sky and blackbody calibrator. The knowledge of its emissivity is important as far as y and μ measurements as concerned. We have re-estimated the XCAL emissivity by using Ray-Tracing techniques. Diffraction problems have been analyzed by a model based on waveguide approximation: it allowed us to define a propagation function τ inside the XCAL V-groove. The emission of the external calibrator distorted with respect to the Black-Body emission may result in lower upper limits to y and μ . New upper limits for distortion parameters y and μ have been calculated considering the new XCAL emissivity. The results are: y up =3.1×10 −5 and μ up =4.5×10 −4 at 95% of confidence. |
| Databáze: | OpenAIRE |
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