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Author  |
Barenboim, G.; Sanchis, H.; Kinney, W.H.; Rios, D. |
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Title |
Bound on thermal y distortion of the cosmic neutrino background |
Type |
Journal Article |
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Year |
2024 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
110 |
Issue |
12 |
Pages |
123535 - 8pp |
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Abstract |
We consider the possibility that the cosmic neutrino background might have a nonthermal spectrum, and investigate its effect on cosmological parameters relative to standard A-cold dark matter (ACDM) cosmology. As a specific model, we consider a thermal y- distortion, which alters the distribution function of the neutrino background by depleting the population of low-energy neutrinos and enhancing the highenergy tail. We constrain the thermal y- parameter of the cosmic neutrino background using cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) measurements, and place a 95%-confidence upper bound of y <= 0.043. The y- parameter increases the number of effective relativistic degrees of freedom, reducing the sound horizon radius and increasing the best-fit value for the Hubble constant H 0 . We obtain an upper bound on the Hubble constant of H 0 = 71.12 km/s/Mpc at 95% confidence, substantially reducing the tension between CMB/BAO constraints and direct measurement of the expansion rate from type-Ia supernovae. Including a spectral distortion also allows for a higher value of the spectral index of scalar fluctuations, with a best-fit of n S = 0.9720 +/- 0.0063, and a 95%-confidence upper bound of n S <= 0.9842. |
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Address |
[Barenboim, Gabriela; Sanchis, Hector] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Burjassot, Spain, Email: gabriela.barenboim@uv.es; |
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Publisher |
Amer Physical Soc |
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Language |
English |
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Original Title |
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Series Volume |
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Edition |
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ISSN |
2470-0010 |
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Notes |
WOS:001386386600005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6397 |
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