Determining neutrino properties using future galaxy redshift surveys

Neutrino mass spectrum and future beta decay experiments

The various experiments on neutrino oscillation evidence that neutrinos have indeed non‐zero masses but cannot provide the absolute neutrino mass scale. This scale of neutrino masses is very important for understanding the evolution and the structure formation of the universe as well as for nuclear and particle physics beyond the present Standard Model. Complementary to deducing constraints on the sum of all neutrino masses from cosmological observations, two different methods to determine the neutrino mass scale in the laboratory are pursued: the search for neutrinoless double β‐decay and the direct neutrino mass search by investigating single β‐decays or electron captures. The former method is not only sensitive to neutrino masses but also probes the Majorana character of neutrinos and thus lepton number violation with high sensitivity. Currently quite a few experiments using different techniques are being constructed, commissioned, or are even running, which aim for a sensitivity on the neutrino mass of (100) meV. The principal methods and these experiments are discussed in this short review.

The discovery of neutrino mass establishes the need for physics beyond the Standard Model. I summarize the status of two- and three-neutrino oscillation parameters from current solar, atmospheric, reactor and accelerator data. Future neutrinoless double beta decay experiments will probe the nature of neutrinos, as well as the absolute scale of neutrino mass, also tested by tritium beta decay spectra and cosmological observations. Sterile neutrinos do not provide a good way to account for the LSND hint, which needs further confirmation. Finally I sketch the main theoretical ideas for generating neutrino mass.

Among three typical energy scales, a neutrino mass scale (mν∼0.1 eV), a GUT scale (MGUT∼1016 GeV), and a TeV scale (MNP∼1 TeV), there is a fascinating relation, i.e. . The TeV scale, MNP, is a new physics scale beyond the standard model which is regarded as supersymmetry in this letter. We suggest a simple supersymmetric neutrinophilic Higgs doublet model, which realizes the above relation dynamically as well as the suitable mν through a tiny vacuum expectation value of the neutrinophilic Higgs doublet without additional scales other than MNP and MGUT. A gauge coupling unification, which is an excellent feature in the supersymmetric standard model, is preserved automatically in this setup.

We show that, in the presence of massive neutrinos, the Galileon gravity model provides a very good fit to the current CMB temperature, CMB lensing and BAO data. This model, which we dub ${\nu} \rm{Galileon}$, when assuming its stable attractor background solution, contains the same set of free parameters as $\Lambda\rm{CDM}$, although it leads to different expansion dynamics and nontrivial gravitational interactions. The data provide compelling evidence ($\gtrsim 6\sigma$) for nonzero neutrino masses, with $\Sigma m_\nu \gtrsim 0.4\ {\rm eV}$ at the $2\sigma$ level. Upcoming precision terrestrial measurements of the absolute neutrino mass scale therefore have the potential to test this model. We show that CMB lensing measurements at multipoles $l \lesssim 40$ will be able to discriminate between the ${\nu} \rm{Galileon}$ and $\Lambda\rm{CDM}$ models. Unlike $\Lambda\rm{CDM}$, the ${\nu} \rm{Galileon}$ model is consistent with local determinations of the Hubble parameter. The presence of massive neutrinos lowers the value of $\sigma_8$ substantially, despite of the enhanced gravitational strength on large scales. Unlike $\Lambda\rm{CDM}$, the ${\nu} \rm{Galileon}$ model predicts a negative ISW effect, which is difficult to reconcile with current observational limits.

We study the CP violation effects from two types of neutrino mass matrices with (i) $(M_\nu)_{ee}=0$, and (ii) $(M_\nu)_{ee}=(M_\nu)_{e\mu}=0$, which can be realized by the high dimensional lepton number violating operators $\bar \ell_R^c\gamma^\mu L_L (D_\mu \Phi)\Phi^2$ and $\bar \ell_R^c l_R (D_\mu{\Phi})^2\Phi^2$, respectively. In (i), the neutrino mass spectrum is in the normal ordering with the lightest neutrino mass within the range $0.002\,{\rm eV}\lesssim m_0\lesssim 0.007\,{\rm eV}$. Furthermore, for a given value of $m_0$, there are two solutions for the two Majorana phases $\alpha_{21}$ and $\alpha_{31}$, whereas the Dirac phase $\delta$ is arbitrary. For (ii), the parameters of $m_0$, $\delta$, $\alpha_{21}$, and $\alpha_{31}$ can be completely determined. We calculate the CP violating asymmetries in neutrino-antineutrino oscillations for both mass textures of (i) and (ii), which are closely related to the CP violating Majorana phases.

The next generation interferometric radio telescope, the Square Kilometre Array (SKA), which will be the most sensitive and largest radio telescope ever constructed, could greatly contribute to the detection, survey and characterization of Gamma Ray Bursts (GRBs). By the SKA, it will be possible to perform the follow up of GRBs even for several months. This approach would be extremely useful to extend the Spectrum Energetic Distribution (SED) from the gamma to the to radio band and would increase the number of radio detectable GRBs. In principle, the SKA could help to understand the physics of GRBs by setting constraints on theoretical models. This goal could be achieved by taking into account multiple observations at different wavelengths in order to obtain a deeper insight of the sources. Here, we present an estimation of GRB radio detections, showing that the GRBs can really be observed by the SKA. The approach that we present consists in determining blind detection rates derived by a very large sample consisting of merging several GRB catalogues observed by current missions as Swift, Fermi, Agile and INTEGRAL and by previous missions as BeppoSAX, CGRO, GRANAT, HETE-2, Ulysses and Wind. The final catalogue counts 7516 distinct sources. We compute the fraction of GRBs that could be observed by the SKA at high and low frequencies, above its observable sky. Considering the planned SKA sensitivity and through an extrapolation based on previous works and observations, we deduce the minimum fluence in the range 15-150 keV. This is the energy interval where a GRB should emit to be detectable in the radio band by the SKA. Results seem consistent with observational capabilities.

In some classes of flavour models based on unified theories with a type I see-saw mechanism, the prediction for the mass of the lightest right-handed neutrino is in conflict with the lower bound from the requirement of successful thermal leptogenesis. We investigate how lifting the absolute neutrino mass scale by adding a type II see-saw contribution proportional to the unit matrix can solve this problem. Generically, lifting the neutrino mass scale increases the prediction for the mass of the lightest right-handed neutrino while the decay asymmetry is enhanced and washout effects are reduced, relaxing the lower bound on the mass of the lightest right-handed neutrino from thermal leptogenesis. For instance in classes of unified theories where the lightest right-handed neutrino dominates the type I see-saw contribution, we find that thermal leptogenesis becomes possible if the neutrino mass scale is larger than about 0.15 eV, making this scenario testable by neutrinoless double beta decay experiments in the near future.

We determine the forecast errors on the absolute neutrino mass scale and the equation of state of dark energy by combining synthetic data from the Dark Energy Survey (DES) and the Cosmic Microwave Background (CMB) Planck surveyor. We use angular clustering of galaxies for DES in 7 redshift shells up to $z\sim 1.7$ including cross-correlations between different redshift shells. We study models with massless and massive neutrinos and three different dark energy models: $\Lambda$CDM ($w=-1$), wCDM (constant $w$), and waCDM (evolving equation of state parameter $w(a)=w_0 + w_{a}(1-a)$). We include the impact of uncertainties in modeling galaxy bias using a constant and a redshift-evolving bias model. For the $\Lambda$CDM model we obtain an upper limit for the sum of neutrino masses from DES+Planck of $\Sigma m_\nu < 0.08$ eV (95\% C.L.) for a fiducial mass of $\Sigma m_\nu = 0.047$ eV, with a 1$\sigma$ error of 0.02 eV, assuming perfect knowledge of galaxy bias. For the wCDM model the limit is $\Sigma m_\nu < 0.10 $ eV. For a wCDM model where galaxy bias evolves with redshift, the upper limit on the sum of neutrino masses increases to 0.19 eV. DES will be able to place competitive upper limits on the sum of neutrino masses of 0.1-0.2 eV and could therefore strongly constrain the inverted mass hierarchy of neutrinos. In a wCDM model the 1$\sigma$ error on constant $w$ is $\Delta w= 0.03$ from DES galaxy clustering and Planck. Allowing $\Sigma m_\nu$ as a free parameter increases the error on $w$ by a factor of 2, with $\Delta w=0.06$. In a waCDM model, in which the dark energy equation of state varies with time, the errors are $\Delta w_0 = 0.2$ and $\Delta w_a = 0.42$. Including neutrinos and redshift dependent galaxy bias increases the errors to $\Delta w_0 = 0.35$ and $\Delta w_a = 0.89$.

We investigate the gravitational lensing effects on neutrino oscillations within the framework of Modified Gravity (MOG). By modeling neutrinos as both plane waves and Gaussian wave packets, we analyze how the presence of a massive lensing object between the neutrino source and detector modifies the flavor transition probabilities. In the plane-wave approximation, we derive analytical expressions for lensing-induced interference patterns, showing explicit dependence on the MOG parameter α , the impact parameters, and the neutrino mass hierarchy. Extending the analysis to a wave-packet framework, we account for decoherence effects and quantify the damping of oscillation amplitudes due to finite energy and spatial spreads of the wave packets. We compute the decoherence length and damping factor for a realistic Sun–Earth system and demonstrate how both the absolute neutrino mass scale and the MOG parameter influence coherence loss. Our results indicate that gravitational lensing in alternative gravity theories can leave observable imprints on neutrino oscillation patterns, offering a novel probe of both neutrino properties and modifications of General Relativity.

The absolute neutrino mass scale is currently unknown, but can be constrained from cosmology. The WiggleZ high redshift star-forming blue galaxy sample is less sensitive to systematics from non-linear structure formation, redshift-space distortions and galaxy bias than previous surveys. We obtain a upper limit on the sum of neutrino masses of 0.60eV (95% confidence) for WiggleZ+Wilkinson Microwave Anisotropy Probe. Combining with priors on the Hubble Parameter and the baryon acoustic oscillation scale gives an upper limit of 0.29eV, which is the strongest neutrino mass constraint derived from spectroscopic galaxy redshift surveys.

The KArlsruhe TRItium Neutrino (KATRIN) experiment will measure the absolute mass scale of neutrinos with a sensitivity of mν = 200 meV/c2 by high-precision spectroscopy close to the tritium β-decay endpoint at 18.6 keV. Its Windowless Gaseous Tritium Source (WGTS) is a β-decay source of high intensity (1011 s−1) and stability, where high-purity molecular tritium at 30 K is circulated in a closed loop with a yearly throughput of 10 kg. To limit systematic effects the column density of the source has to be stabilized at the 10−3 level. This requires extensive sensor instrumentation and dedicated control and monitoring systems for parameters such as the beam tube temperature, injection pressure, gas composition and so on. In this paper, we give an overview of these systems including a dedicated laser-Raman system as well as several β-decay activity monitors. We also report on the results of the WGTS demonstrator and other large-scale test experiments giving proof-of-principle that all parameters relevant to the systematics can be controlled and monitored on the 10−3 level or better. As a result of these works, the WGTS systematics can be controlled within stringent margins, enabling the KATRIN experiment to explore the neutrino mass scale with the design sensitivity.

The binding-energy differences for163Hoq+and163Dyq+ions with ionization degreesq=38, 39, and 40 are calculated. The calculations are performed using the large-scale relativistic configuration-interaction and relativistic coupled-clusters methods. The contributions from quantum-electrodynamics, nuclear-recoil, and frequency-dependent Breit-interaction effects are taken into account. The final uncertainty does not exceed 1 eV. Combining the obtained results with the binding-energy difference for neutral atoms calculated in [I.M.Savelyev, M.Y. Kaygorodov, Y.S. Kozhedub, I.I. Tupitsyn, and V.M. Shabaev, Phys. Rev. A105, 012806 (2022)], we get the secondary differences of the ion–atom binding energies. These values can be used to evaluate the amount of energy released in the electron capture process in163Hoatom (theQvalue), provided mass differences of highly charged ions163Hoq+and163Dyq+is known from experiment. TheQvalue is required by experiments on the determination of the absolute scale of the electron neutrino mass by studying the beta-decay process.

The Square Kilometre Array (SKA) project is responsible for developing the SKA Observatory, the world’s largest radio telescope, with eventually over a square kilometre of collecting area and including a general headquarters as well as two radio telescopes: SKA1-Mid in South Africa and SKA1-Low in Australia. The SKA project consists of a number of subsystems (elements) among which the Telescope Manager (TM) is the one involved in controlling and monitoring the SKA telescopes. The TM element has three primary responsibilities: management of astronomical observations, management of telescope hardware and software subsystems, management of data to support system operations and all stakeholders (operators, maintainers, engineers and science users) in achieving operational, maintenance and engineering goals. Operators, maintainers, engineers and science users will interact with TM via appropriate user interfaces (UI). The TM UI framework envisaged is a complete set of general technical solutions (components, technologies and design information) for implementing a generic computing system (UI platform). Such a system will enable UI components to be instantiated to allow for human interaction via screens, keyboards, mouse and to implement the necessary logic for acquiring or deriving the information needed for interaction. It will provide libraries and specific Application Programming Interfaces (APIs) to implement operator and engineer interactive interfaces. This paper will provide a status update of the TM UI framework, UI platform and UI components design effort, including the technology choices, and discuss key challenges in the TM UI architecture, as well as our approaches to addressing them.

Fast radio bursts (FRBs) are mysterious extragalactic radio signals. Revealing their origin is one of the central foci in modern astronomy. Previous studies suggest that occurrence rates of non-repeating and repeating FRBs could be controlled by the cosmic stellar-mass density (CSMD) and cosmic star formation-rate density (CSFRD), respectively. The Square Kilometre Array (SKA) is one of the best future instruments to address this subject due to its high sensitivity and high-angular resolution. Here, we predict the number of FRBs to be detected with the SKA. In contrast to previous predictions, we estimate the detections of non-repeating and repeating FRBs separately, based on latest observational constraints on their physical properties including the spectral indices, FRB luminosity functions, and their redshift evolutions. We consider two cases of redshift evolution of FRB luminosity functions following either the CSMD or CSFRD. At $z$ ≳ 2, $z$ ≳ 6, and $z$ ≳ 10, non-repeating FRBs will be detected with the SKA at a rate of ∼104, ∼102, and ∼10 (sky−1 d−1), respectively, if their luminosity function follows the CSMD evolution. At $z$ ≳ 1, $z$ ≳ 2, and $z$ ≳ 4, sources of repeating FRBs will be detected at a rate of ∼103, ∼102, and ≲10 (sky−1 d−1), respectively, assuming that the redshift evolution of their luminosity function is scaled with the CSFRD. These numbers could change by about one order of magnitude depending on the assumptions on the CSMD and CSFRD. In all cases, abundant FRBs will be detected by the SKA, which will further constrain the luminosity functions and number density evolutions.