Observational constraints on neutrino masses in rolling tachyon field model

Abstract

In the standard model of particles physics, neutrinos have no mass. In this model, there are three massless neutrino species that only interact through the weak force. Neutrinos can leave imprint in several cosmological data sets. Cosmological data provide an independent and powerful tool to tackle the absolute scale of neutrino and to study its properties. The observational measurements taken by the Planck satellite provide extremely tight upper bounds on the total neutrino mass scale $\sum m_{\nu }< 0.12 \textrm{eV}$ $(95\%$ confidence level (CL)). In this paper, the constraints on the total neutrino mass $\sum m_{\nu }$ and extra relativistic degrees of freedom $N_{\textrm{eff}}$ in a rolling tachyon model, with steep runaway type of potentials non-minimally coupled to massive neutrino matter, are investigated. The observational data include the type Ia supernovae (SN) observation (Pantheon compilation and Union2 data), CC and combination of CMB + CC + Pantheon data that are used in this work. For CMB + CC + Pantheon data, we have found that the neutrino mass is closely constrained to $\sum m_{\nu }< 0.273 \textrm{eV}$ $(95\%$ confidence level (CL)) which is in good agreement with the 2018 Planck results where the limit of the total neutrino mass is $\sum m_{\nu }< 0.27 \textrm{eV}$$95\%$ CL TT, TE, EE + lowE + Lensing [CamSpec]), and we also find $N_{\textrm{eff}}=3.29^{+0.05}_{-0.05}$ $68\%$ CL which is in good agreement with the results of Planck with $N_{\textrm{eff}}=3.27^{+0.15}_{-0.15}$$68\%$CL TE, TT, EE, LowE + lensing + BAO + R18). In order to reconstruct the history of the universe, we reconstruct the deceleration parameter q(z) based on the best fitted parameters of the model. The evolution of the model shows that the universe start from radiation dominated epoch continues toward matter-dominated epoch at deceleration–acceleration transition $z_{tr}=0.76,$ enters the acceleration phase and with current value $q_{0}=-0.58$ and moves toward stable dark energy dominated. The obtained values of $z_{tr}$ and $q_{0}$ are in good agreement with observations.

Appendix

Figures 4, 5 and 6 show the one-dimensional likelihood for parameters $\sum m_{\nu },N_{\textrm{eff}},h,$ respectively.

Fig. 4

One-dimensional likelihood for $\sum m_{\nu }$ using Union2, Pantheon and CC data

Fig. 5

One-dimensional likelihood for $N_{\textrm{eff}}$ using Union2, Pantheon, CC and CMB+CC+Pantheon data

Fig. 6

One-dimensional likelihood for parameter h using Union2, Pantheon, CC and CMB+CC+Pantheon data