09 - Cosmic neutrinos
- Julien Lesgourgues ()
09 - Cosmic neutrinos
- Julien Lesgourgues ()
Martina Gerbino (University of Rome 'Sapienza')
12/15/15, 2:00 PM
The absolute scale of neutrino masses is one of the main open issues both in cosmology and particle physics. Current experimental strategies involve i) measurements exploiting kinematics effects in beta decay, ii) searches for neutrinoless double beta decay ('0n2b'), and iii) cosmological observations. The three approaches are complementary, each of them presenting its own advantages and...
Dr Carmelita Carbone (National Institute for Astrophysics - INAF)
12/15/15, 2:21 PM
I will present the first set of cosmological simulations produced within the “Dark Energy and Massive Neutrino Universe” (DEMNUni) project. These simulations are characterized by L=2 Gpc/h, Npart=2 x 2048^3, a baseline LCDM-Planck cosmology, and four different total neutrino masses, Mnu=0, 0.17, 0.3, 0.53 eV, with a degenerate mass spectrum. They are the largest N-body simulations to date...
Dr Simeon Bird (Johns Hopkins University)
12/15/15, 2:42 PM
The massive neutrino background makes up a component of the dark matter, and as such affects the growth of large-scale structure, such as galaxy clusters. This affords us an opportunity to measure the neutrino mass. However, to do this we must accurately and efficiently characterize how neutrinos affect structure growth. I will describe a new method for including massive neutrinos in N-body...
12/15/15, 3:03 PM
I will present the constraint on massive neutrinos that was obtained recently using Lyman-alpha forest, BAO and CMB data. I will first describe the measurement of the power spectrum in the Lyman-alpha forest observed in quasars of the SDSS/BOSS survey. I will then present the extensive suite of N-body/hydro simulations that has been developed specifically for the purpose of this study, and...
Francisco Villaescusa-Navarro (OATS-INAF)
12/15/15, 3:24 PM
Neutrinos are described as fundamental particles by the standard model of particle physics. The fact that neutrinos are massive, as demonstrated by neutrino oscillations experiments, point towards physics beyond the standard model. Thus, one of the most important questions in modern physics is: which are the masses of the neutrinos? Current tightest constrain on the sum of the neutrino masses...
Massimiliano Lattanzi (University of Ferrara)
12/15/15, 4:15 PM
Cosmological observations represent a powerful tool to constrain neutrino physics. In particular, observations of the temperature and polarization anisotropies of the cosmic microwave background (CMB) have the potential to constrain the properties of relic neutrinos, and possibly of additional light relic particles in the Universe. Even if all current cosmological data are well in agreement...
12/15/15, 4:36 PM
The motivation for new non-standard interactions in the sterile neutrino sector arises from the tension between oscillation data and cosmological data, indeed the former point towards the existence of one (or more) light sterile neutrino in the eV mass range, while the latter disfavor additional massive species with high statistical significance. However a partial thermalization induced by...
Dr Antonella Garzilli (Leiden University)
12/15/15, 4:57 PM
We reconsider the problem of determining the warmness of dark matter from the growth of large scale structures. In particular, we have re-analyzed the previous work of Viel et al 2013, based on high resolution Lyman-alpha forest spectra. In fact, the flux power spectrum exhibits a cut-off below ~ 1.5 Mpc/h, this may be explained by the temperature of the intergalactic medium (IGM) or be...
310. A loophole to the electromagnetic cascade theory : Solving the lithium problem with a sterile neutrino.
Vivian Poulin (Unite Reseaux du CNRS (FR))
12/15/15, 5:18 PM
After a recap of the standard e.m. cascade theory, I will discuss a loophole that can have a large effect in the early universe, notably in altering primordial nucleosynthesis bounds on electromagnetically decaying relic particles. I will finally show how this may greatly simplify the possibility to address the long-standing "lithium problem" in terms of new physics models, and solve it...
Pablo Fernández de Salas (IFIC - CSIC/Universidad de Valencia)
12/15/15, 5:39 PM
We have performed a new numerical calculation of the decoupling process of neutrinos in the early Universe, including the values of all mixing parameters from a recent analysis, taking into account the full set of differential equations for the neutrino density matrices (equivalent to the occupation numbers for mixed neutrinos). Our results are important for fixing the radiation content of the...
Florian Führer (Institut für Theoretische Physik, Universität Heidelberg)
12/15/15, 6:00 PM
I will present a new first principle approach for higher order perturbation theory for hot and warm dark matter in large scale structure. The approach is based on a non-linear generalization of Gilbert's equation. Combined with standard perturbation theory, it allows to calculate N-point statistics of density perturbations in mixed cold+hot dark matter cosmologies. I apply the theory to...
12/15/15, 6:20 PM
There is now no doubt that neutrinos are massive particles fully involved in the nonlinear growth of the large-scale structure of the universe. A problem is that their nonlinear behavior is particularly difficult to describe by theoretical models. In my talk, I will present a new method allowing to deal with massive neutrinos beyond the linear regime. The key idea is to describe neutrinos as a...
12/15/15, 6:40 PM
The transition of cosmological massive neutrinos into the non-relativistic regime acts as a decoherence process which also changes the oscillation probability, reaching different values for the asymptotic flavour composition. Furthermore, this effect could also increase the entropy inside the neutrino ensemble, triggering the formation of bulk viscosity and introducing fluctuations in the...
Graziano Rossi (Sejong University)
12/15/15, 6:43 PM
We present joint constraints on the number of effective neutrino species Neff and the sum of neutrino masses, using a technique based on state-of-the-art hydrodynamical simulations with massive neutrinos, which allows one to exploit the full information contained in the one-dimensional Lyman-Alpha forest flux power spectrum complemented by additional cosmological probes. Our results provide...