Helioseismology can test the Maxwell-Boltzmann distribution

Reports on Progress in Physics, 2011

Neutrinos are fundamental particles ubiquitous in the Universe and whose properties remain elusive despite more than 50 years of intense research activity. This review illustrates the importance of solar neutrinos in Astrophysics, Nuclear Physics, and Particle Physics. After a description of the historical context, we remind the reader of the noticeable properties of these particles and of the stakes of the solar neutrino puzzle. The Standard Solar Model triggered persistent efforts in fundamental Physics to predict the solar neutrino fluxes, and its constantly evolving predictions have been regularly compared to the detected neutrino signals. Anticipating that this standard model could not reproduce the internal solar dynamics, a Seismic Solar Model was developed which enriched theoretical neutrino flux predictions with in situ observation of acoustic and gravity waves propagating in the Sun. This seismic model contributed to the stabilization of the neutrino flux predictions. This review reminds the main historical steps, from the pioneering Homestake mine experiment and the GALLEX-SAGE experiments capturing the first pp neutrinos. It emphasizes the importance of the Superkamiokande and SNO detectors. Both experiments demonstrated that the solar-emitted electronic neutrinos are partially transformed into other neutrino flavors before reaching the Earth. This sustained experimental effort opens the door to Neutrino Astronomy, with long-base lines and underground detectors. The success of BOREXINO in detecting the 7 Be neutrino signal alone instills confidence in the physicists ability to detect each neutrino source separately. It justifies the building of a new generation of detectors to measure the entire solar neutrino spectrum with greater detail, as well as supernova neutrinos. A coherent picture emerged from neutrino physics and helioseismology. Today, new paradigms take shape in these two fields: the neutrinos are massive particles, but their masses are still unknown, and the research on the solar interior is focusing on the dynamical aspects and on signature of dark matter. The magnetic moment of the neutrino begins to be an actor of stellar evolution. The third part of the review is dedicated to this prospect. The understanding of the crucial role of both rotation and magnetism in solar physics benefit from SoHO, SDO, and PICARD space observations, and from new prototype like GOLF-NG. The magnetohydrodynamical view of the solar interior is a new way of understanding the impact of the Sun on the Earth environment and climate. For now, the particle and stellar challenges seem decoupled, but this is only a superficial appearance. The development of asteroseismology-with the COROT and KEPLER spacecrafts-and of neutrino physics will both contribute to improvements in our understanding of, for instance, supernova explosions. This shows the far-reaching impact of Neutrino and Stellar Astronomy.

Nuclear Physics A, 1997

Constraints on the neutrino fluxes ~p, ~B, ¢CNO and ~B~ are derived from the available experimental results. Physical implications are discussed by means of non-extensive statistics which takes into account many-body effects and long-range interactions. The different reduction factors for TBe and SB fluxes with respect to their standard solar model values are physically understood, with proper shapes of the shape of the electron and proton distribution functions.

Nuclear Physics B - Proceedings Supplements, 1996

We review recent advances concerning helioseismology, solar models and solar neutrinos. Particularly we shall address the following points: i) helioseismic tests of recent SSMs; ii)the accuracy of the helioseismic determination of the sound speed near the solar center; iii)predictions of neutrino fluxes based on helioseismology, (almost) independent of SSMs; iv)helioseismic tests of exotic solar models. Fig. 1. The isothermal sound speed profile, u = P/ρ, as derived from helioseismic observations, from 2 . Fig. 2. The predicted BP98 sound speeds compared with five different helioseismological measurements 7 , from 1

Physics Letters B, 2001

We show that models for screening of nuclear reactions in the Sun can be tested by means of helioseismology. As well known, solar models using the weak screening factors are in agreement with data. We find that the solar model calculated with the anti screening factors of Tsytovitch is not consistent with helioseismology, both for the sound speed profile and for the depth of the convective envelope. Moreover, the difference between the no-screening and weak screening model is significant in comparison with helioseismic uncertainty. In other words, the existence of screening can be proved by means of helioseismology.

The Astrophysical Journal, 2001

Three helioseismic instruments on the Solar and Heliospheric Observatory have observed the Sun almost continuously since early 1996. This has led to detailed study of the biases induced by the instruments that measure intensity or Doppler velocity variation. Photospheric turbulence hardly influences the tiny signature of conditions in the energy-generating core in the low-order modes, which are therefore very informative. We use sound-speed and density profiles inferred from GOLF and MDI data including these modes, together with recent improvements to stellar model computations, to build a spherically symmetric seismically adjusted model in agreement with the observations. The model is in hydrostatic and thermal balance and produces the present observed luminosity. In constructing the model, we adopt the best physics available, although we adjust some fundamental ingredients, well within the commonly estimated errors, such as the p-p reaction rate (ϩ1%) and the heavy-element abundance (ϩ3.5%); we also examine the sensitivity of the density profile to the nuclear reaction rates. Then, we deduce the corresponding emitted neutrino fluxes and consequently demonstrate that it is unlikely that the deficit of the neutrino fluxes measured on Earth can be explained by a spherically symmetric classical model without neutrino flavor transitions. Finally, we discuss the limitations of our results and future developments.

Physica A: Statistical Mechanics and its Applications, 2003

The Super-Kamiokande best global fit, which includes data from SNO, Gallium and Chlorine experiments, results in a hep neutrino contribution to the signals that, even after oscillation, is greater than the SSM prediction. The solar hep neutrino flux that would yield this contribution is four times larger than the one predicted by the SSM. Recent detailed calculations exclude that the astrophysical factor S hep (0) could be wrong by such a large factor. Given the reliability of the temperature and densities profiles inside the Sun, this experimental result indicates that plasma effects are important for this reaction. We show that a slight enhancement of the high-energy tail, enhancement that is of the order of the deviations from the Maxwell-Boltzmann distribution expected in the solar core plasma, produces an increment of the hep rate of the magnitude required. We verified that the other neutrino fluxes remain compatible with experimental signals and SSM predictions. Better measurements of the high-energy tail of the neutrino spectrum would improve our understanding of reaction rates in the solar plasma.

Physical Review D, 1994

For standard neutrinos, recent solar neutrino results together with the assumption of a nuclearly powered Sun imply severe constraints on the individual components of the total neutrino flux: Φ Be ≤ 0.7 × 10 9 cm -2 s -1 , Φ CNO ≤ 0.6×10 9 cm -2 s -1 , and 64×10 9 cm -2 s -1 ≤ Φ pp+pep ≤ 65×10 9 cm -2 s -1 (at 1σ level). The bound on Φ Be is in strong disagreement with the standard solar model (SSM) prediction Φ SSM Be ≈ 5 × 10 9 cm -2 s -1 . We study a large variety of non-standard solar models with low inner temperature, finding that the temperature profiles T (m) follow the homology relationship: T (m) = kT SSM (m), so that they are specified just by the central temperature T c . There is no value of T c which can account for all the available experimental results. Even if we only consider the Gallium and Kamiokande results, they remain incompatible. Lowering the cross section p + 7 Be → γ + 8 B is not a remedy. The shift of the nuclear fusion chain towards the pp-I termination could be induced by a hypothetical low energy resonance in the 3 He + 3 He reaction. This mechanism gives a somehow better, but still bad fit to the combined experimental data. We also discuss what can be learnt from new generation experiments, planned for the detection of monochromatic solar neutrinos, about the properties of neutrinos and of the Sun.

Physical Review D, 1999

The 3 He abundance is not constrained by helioseismic data. Mixing of 3 He inside the solar core by processes not included in the solar standard model (SSM) has been recently proposed as possible solution to the solar neutrino problem. We have performed a model independent analysis of solar neutrino fluxes using practically arbitrary 3 He mixing. In addition, we have been simultaneously varying within very wide ranges the temperature in the neutrino production zone and the astrophysical factors, S 17 and S 34 , of the p + 7 Be and 3 He + 4 He cross sections. Seismic data are used as constraints, but the solarluminosity constraint is not imposed. It is demonstrated that even allowing 3 He abundances higher by factors up to 16 than in the SSM, temperatures 5% (or more) lower, the astrophysical factor S 17 up to 40% higher, and varying S 34 in the range (-20% ,+40%), the best fit is still more than 5σ away from the observed fluxes. We conclude that practically arbitrary 3 He mixing combined with independent variations of temperature and cross-sections cannot explain the observed solar neutrino fluxes.

Physical review letters, 1996

Recent solar neutrino experiments have shown that both φ(8 B) and the neutrino flux ratio φ(7 Be)/φ(8 B) are substantially below their standard solar model values, leading some to discount the possibility of an astrophysical solution to the solar neutrino puzzle. We test this conclusion phenomenologically and find that the discrepancies can be significantly reduced by a distinctive pattern of core mixing on timescales characteristic of 3 He equilibration.

The Astrophysical Journal, 2006

A search has been made for neutrinos from the hep reaction in the Sun and from the diffuse supernova neutrino background (DSNB) using data collected during the first operational phase of the Sudbury Neutrino Observatory, with an exposure of 0.65 kilotonne-years. For the hep neutrino search, two events are observed in the effective electron energy range of 14.3 MeV < Teff < 20 MeV where 3.1 background events are expected. After accounting for neutrino oscillations, an upper limit of 2.3 x 104 cm-2s-1 at the 90 percent confidence level is inferred on the integral total flux of hep neutrinos. For DSNB neutrinos, no events are observed in the effective electron energy range of 21 MeV < Teff < 35 MeV and, consequently, an upper limit on the nu e component of the DSNB fluxin the neutrino energy range of 22.9 MeV < E nu < 36.9 MeV of 70 cm-2-1 is inferred eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. at the 90 percent confidence level. This is an improvement by a factor of 6.5 on the previous best upper limit on the hep neutrino flux and by two orders of magnitude on the previous upper limit on the nu e component of the DSNB flux. arXiv:hep-ex/0607010 v2 ABSTRACT A search has been made for neutrinos from the hep reaction in the Sun and from the diffuse supernova neutrino background (DSNB) using data collected during the first operational phase of the Sudbury Neutrino Observatory, with an exposure of 0.65 kilotonne-years. For the hep neutrino search, two events are observed in the effective electron energy range of 14.3 MeV < T eff < 20 MeV where 3.1 background events are expected. After accounting for neutrino oscillations, an upper limit of 2.3 × 10 4 cm −2 s −1 at the 90% confidence level is inferred on the integral total flux of hep neutrinos. For DSNB neutrinos, no events are observed in the effective electron energy range of 21 MeV < T eff < 35 MeV and, consequently, an upper limit on the ν e component of the DSNB flux in the neutrino energy range of 22.9 MeV < E ν < 36.9 MeV of 70 cm −2 s −1 is inferred at the 90% confidence level. This is an improvement by a factor of 6.5 on the previous best upper limit on the hep neutrino flux and by two orders of magnitude on the previous upper limit on the ν e component of the DSNB flux.