Cosmological neutrino mass and abundance measurements are reaching unprecedented precision. Testing their stability versus redshift and scale is a crucial issue, as it can serve as a guide for optimizing ongoing and future searches. Here, we perform such analyses, considering a number of redshift, scale, and redshift-and-scale nodes. Concerning the k-space analysis of Σmν, cosmic microwave background (CMB) observations are crucial, as they lead the neutrino mass constraints. Interestingly, some data combinations suggest a nonzero P value for the neutrino mass with 2σ significance. The most constraining bound we find is Σmν < 0.54 eV at 95% confidence level (CL) in the [10−3,10−2]h/Mpc k-bin, a limit that barely depends on the data combination. Regarding the redshift- and scale-dependent neutrino mass constraints, high redshifts (z?> 100) and scales in the range [10−3,10−1]h/Mpc provide the best constraints. The least constraining bounds are obtained at very low redshifts [0,0.5] and also at very small scales (k?> 0.1 h/Mpc) due to the absence of observations. Highly relevant is the case of the [100, 1100], [10−2,10−1]h/Mpc redshift-scale bin, where a 2 − 3σ evidence for a nonzero neutrino mass is obtained for all data combinations. The bound from CMB alone at 68% CL is 0.63+0.20−0.24 eV, and the one for the full dataset is 0.56+0.20−0.23 eV, clearly suggesting a nonzero neutrino mass at these scales, possibly related to a deviation of the integrated Sachs-Wolfe amplitude in this redshift range. Concerning the analysis of Neff in the k-space, at intermediate scales ranging from k = 10−3 h/Mpc to k = 10−1 h/Mpc, accurate CMB data provide very strong bounds, the most robust one being Neff = 3.09 ± 0.14, comparable to the standard expected value without a k-bin analysis. If a nonzero neutrino mass is considered, the bounds on the Neff values at the different k-bins are largely unaffected, and the 95% CL tightest limit we find for the neutrino mass in this case is Σmν < 0.205 eV from the full dataset. Finally, the z and k analyses of Neff indicate a high constraining power of cosmological observations at high redshifts and intermediate scales [10−2,10−1] h/Mpc when extracting the binned values of this parameter.
Scale and redshift dependent limits on cosmic neutrino properties
Gariazzo, Stefano
2025-01-01
Abstract
Cosmological neutrino mass and abundance measurements are reaching unprecedented precision. Testing their stability versus redshift and scale is a crucial issue, as it can serve as a guide for optimizing ongoing and future searches. Here, we perform such analyses, considering a number of redshift, scale, and redshift-and-scale nodes. Concerning the k-space analysis of Σmν, cosmic microwave background (CMB) observations are crucial, as they lead the neutrino mass constraints. Interestingly, some data combinations suggest a nonzero P value for the neutrino mass with 2σ significance. The most constraining bound we find is Σmν < 0.54 eV at 95% confidence level (CL) in the [10−3,10−2]h/Mpc k-bin, a limit that barely depends on the data combination. Regarding the redshift- and scale-dependent neutrino mass constraints, high redshifts (z?> 100) and scales in the range [10−3,10−1]h/Mpc provide the best constraints. The least constraining bounds are obtained at very low redshifts [0,0.5] and also at very small scales (k?> 0.1 h/Mpc) due to the absence of observations. Highly relevant is the case of the [100, 1100], [10−2,10−1]h/Mpc redshift-scale bin, where a 2 − 3σ evidence for a nonzero neutrino mass is obtained for all data combinations. The bound from CMB alone at 68% CL is 0.63+0.20−0.24 eV, and the one for the full dataset is 0.56+0.20−0.23 eV, clearly suggesting a nonzero neutrino mass at these scales, possibly related to a deviation of the integrated Sachs-Wolfe amplitude in this redshift range. Concerning the analysis of Neff in the k-space, at intermediate scales ranging from k = 10−3 h/Mpc to k = 10−1 h/Mpc, accurate CMB data provide very strong bounds, the most robust one being Neff = 3.09 ± 0.14, comparable to the standard expected value without a k-bin analysis. If a nonzero neutrino mass is considered, the bounds on the Neff values at the different k-bins are largely unaffected, and the 95% CL tightest limit we find for the neutrino mass in this case is Σmν < 0.205 eV from the full dataset. Finally, the z and k analyses of Neff indicate a high constraining power of cosmological observations at high redshifts and intermediate scales [10−2,10−1] h/Mpc when extracting the binned values of this parameter.
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