Related papers: Are cosmological neutrinos free-streaming?
We show that if the evolution of cosmic ray sources follows that of active galactic nuclei, the upper limit on the diffuse flux of tau neutrinos from the Pierre Auger Observatory marginally constrains the proton fraction at the end of the…
We discuss decays of ultra-relativistic neutrinos over cosmological distances by solving the decay equation in terms of its redshift dependence. We demonstrate that there are significant conceptual differences compared to more simplified…
Perturbations in the cosmic neutrino background produce a characteristic phase shift in the acoustic oscillations imprinted in the anisotropies of the cosmic microwave background (CMB), providing a unique observational probe of neutrino…
There are well-known bounds on light neutrino masses from cosmological energy density arguments. These arguments assume the neutrinos to be non-degenerate. We show how these bounds are affected if the neutrinos are degenerate. In this case,…
We present here a scenario, based on a low reheating temperature T_R << 100 MeV at the end of (the last episode of) inflation, in which the coupling of sterile neutrinos to active neutrinos can be as large as experimental bounds permit…
We consider heavy sterile neutrinos $\nu_s$, with mass in the range 10 MeV $\lesssim m_s \lesssim m_{\pi} \sim 135$ MeV, thermally produced in the early universe and freezing out after the QCD phase transition. The existence of these…
Cosmology cannot rule out the solution nu_mu <-> nu_s to the atmospheric neutrino data and thus only Earth experiments will be able to give a definitive answer. This conclusion holds when a generation of lepton number is taken into account…
We reconsider neutrino decay as an explanation for atmospheric neutrino observations. We show that if the mass-difference relevant to the two mixed states \nu_\mu and \nu_\tau is very small (< 10^{-4} eV^2), then a very good fit to the…
Within the context of hot big-bang cosmology, a cosmic background of presently low energy neutrinos is predicted to exist in concert with the photons of the cosmic background radiation. The number density of the cosmological neutrinos is of…
It is possible that the strongest interactions between dark matter and the Standard Model occur via the neutrino sector. Unlike gamma rays and charged particles, neutrinos provide a unique avenue to probe for astrophysical sources of dark…
If massive sterile neutrinos exist, their decays into photons and/or electron-positron pairs may give rise to observable consequences. We consider the possibility that MeV sterile neutrino decays lead to the diffuse positron annihilation…
The low second acoustic peak in the recent Boomerang data may indicate a cosmological baryon density which is larger than allowed by standard big bang nucleosynthesis. We show that the decay of the tau-neutrino: nu_tau -> nu_e + phi, where…
We solve the Boltzmann equation for cosmological neutrinos around the epoch of the electron-positron annihilation in order to verify the freeze-out approximation and to compute accurately the cosmological neutrino distribution function. We…
Sterile neutrinos are one of the most promising Warm Dark Matter candidates. By considering their radiative- and pion-decay channels, we derive the allowed contribution of sterile neutrinos to the X-ray, optical and near-infrared cosmic…
We have performed a careful analysis of constraints on the neutrino mass from current cosmological data. Combining data from the cosmic microwave background and the 2dF galaxy survey yields an upper limit on the sum of the three neutrino…
Cosmology at present provides the nominally strongest constraint on the masses of standard model neutrinos. However, this constraint extremely dependent on the nature of the dark energy component of the Universe. When the dark energy…
Effective field theory of dark matter fluid on large scales predicts the presence of viscosity of the order of $10^{-6} H_0 M_P^2$. It has been shown that this magnitude of viscosities can resolve the discordance between large scale…
Present cosmological observations yield an upper bound on the neutrino mass which is significantly stronger than laboratory bounds. However, the exact value of the cosmological bound is model dependent and therefore less robust. Here, I…
Sterile neutrinos with mass ~1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these…
In this paper we investigate a time-varying neutrino mass model, motivated by the mild tension between cosmic microwave background (CMB) measurements of the matter fluctuations and those obtained from low-redshift data. We modify the…