Reducing the $H_0$ and ${\sigma }_8$ tensions with dark matter-neutrino interactions

The introduction of dark matter-neutrino interactions modifies the cosmic microwave background (CMB) angular power spectrum at all scales, thus affecting the reconstruction of the cosmological parameters. Such interactions can lead to a slight increase of the value of $H_0$ and a slight decrease of $S_8\equiv {\sigma }_8\sqrt{{\mathrm{\Omega }}_m/0.3}$, which can help reduce somewhat the tension between the CMB and weak lensing or Cepheids data sets. Here we show that it is impossible to solve both tensions simultaneously. While the 2015 Planck temperature and low multipole polarization data combined with the Cepheids data sets prefer large values of the Hubble rate (up to $H_0={72.1}_{-1.7}^{+1.5}\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$, when $N_{\mathrm{eff}}$ is free to vary), the ${\sigma }_8$ parameter remains too large to reduce the ${\sigma }_8$ tension. Adding high multipole Planck polarization data does not help since this data shows a strong preference for low values of $H_0$, thus worsening current tensions, even though they also prefer smaller value of ${\sigma }_8$.

Figure 1

The temperature and polarization CMB angular power spectra in the presence of dark matter-neutrino interactions.

Figure 2

The lensing potential power spectrum in the presence of dark matter-neutrino interactions.

Figure 3

Triangle plot showing the 1D and 2D posterior distributions of the cosmological parameters for Planck $\mathrm{TT}+\mathrm{lowTEB}$ in the $\mathrm{\Lambda }\mathrm{CDM}+u+N_{\mathrm{eff}}$ scenario.

Figure 4

Triangle plot showing the 1D and 2D posterior distributions of the cosmological parameters for Planck $\mathrm{TT}+\mathrm{lowTEB}$ in the $\mathrm{\Lambda }\mathrm{CDM}+u+\mathrm{\Sigma }{m}_{\nu }$ scenario.

Figure 5

Triangle plot showing the 1D and 2D posterior distributions of the cosmological parameters for Planck $\mathrm{TT}+\mathrm{lowTEB}$ in the $\mathrm{\Lambda }\mathrm{CDM}+u+N_{\mathrm{eff}}+\mathrm{\Sigma }{m}_{\nu }$ scenario.

Figure 6

Triangle plot showing the 1D and 2D posterior distributions of the cosmological parameters for Planck $\mathrm{TTTEEE}+\mathrm{lowTEB}$ in the $\mathrm{\Lambda }\mathrm{CDM}+u$ scenario.