496 research outputs found

    Shadows of Relic Neutrino Masses and Spectra on Highest Energy GZK Cosmic Rays

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    The Ultra High Energy (UHE) neutrino scattering onto relic cosmic neutrinos in galactic and local halos offers an unique way to overcome GZK cut-off. The UHE nu secondary of UHE photo-pion decays may escape the GZK cut-off and travel on cosmic distances hitting local light relic neutrinos clustered in dark halos. The Z resonant production and the competitive W^+W^-, ZZ pair production define a characteristic imprint on hadronic consequent UHECR spectra. This imprint keeps memory both of the primary UHE nu spectra as well as of the possible relic neutrino masses values, energy spectra and relic densities. Such an hadronic showering imprint should reflect into spectra morphology of cosmic rays near and above GZK 10^{19}-10^{21}eV cut-off energies. A possible neutrino degenerate masses at eVs or a more complex and significant neutrino mass split below or near Super-Kamiokande \triangle m_{\nu_{SK}}= 0.1 eV masses might be reflected after each corresponding Z peak showering, into new twin unexpected UHECR flux modulation behind GZK energies: E_{p} sim 3(frac{triangle m_{\nu_{SK}}}/m_{\nu}10^{21}),eV. Other shadowsof lightest, nearly massless, neutrinos m_{nu_{2K} simeq 0.001eV simeq kT_{\nu}, their lowest relic temperatures, energies and densities might be also reflected at even higher energies edges near Grand Unification: E_{p} \sim 2.2(m_{\nu_{2K}/E_{\nu}})10^{23}, eV .Comment: 14 pages, 6 Figures,Invited Talk Heidelberg DARK 200

    Nonlinear interplay of Alfven instabilities and energetic particles in tokamaks

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    The confinement of energetic particles (EP) is crucial for an efficient heating of tokamak plasmas. Plasma instabilities such as Alfven Eigenmodes (AE) can redistribute the EP population making the plasma heating less effective, and leading to additional loads on the walls. The nonlinear dynamics of toroidicity induced AE (TAE) is investigated by means of the global gyrokinetic particle-in-cell code ORB5, within the NEMORB project. The nonperturbative nonlinear interplay of TAEs and EP due to the wave-particle nonlinearity is studied. In particular, we focus on the nonlinear modification of the frequency, growth rate and radial structure of the TAE, depending on the evolution of the EP distribution in phase space. For the ITPA benchmark case, we find that the frequency increases when the growth rate decreases, and the mode shrinks radially. This nonlinear evolution is found to be correctly reproduced by means of a quasilinear model, namely a model where the linear effects of the nonlinearly modified EP distribution function are retained.Comment: Submitted to Plasma Phys. Control. Fusio

    An extended hybrid magnetohydrodynamics gyrokinetic model for numerical simulation of shear Alfv\'en waves in burning plasmas

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    Adopting the theoretical framework for the generalized fishbonelike dispersion relation, an extended hybrid magnetohydrodynamics gyrokinetic simulation model has been derived analytically by taking into account both thermal ion compressibility and diamagnetic effects in addition to energetic particle kinetic behaviors. The extended model has been used for implementing an eXtended version of Hybrid Magnetohydrodynamics Gyrokinetic Code (XHMGC) to study thermal ion kinetic effects on Alfv\'enic modes driven by energetic particles, such as kinetic beta induced Alfv\'en eigenmodes in tokamak fusion plasmas

    Nonlinear dynamics of beta induced Alfv\'en eigenmode driven by energetic particles

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    Nonlinear saturation of beta induced Alfv\'en eigenmode, driven by slowing down energetic particles via transit resonance, is investigated by the nonlinear hybrid magnetohyrodynamic gyro-kinetic code (XHMGC). Saturation is characterized by frequency chirping and symmetry breaking between co- and counter-passing particles, which can be understood as the the evidence of resonance-detuning. The scaling of the saturation amplitude with the growth rate is also demonstrated to be consistent with radial resonance detuning due to the radial non-uniformity and mode structure

    Cosmological Parameters from the 2003 flight of BOOMERANG

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    We present the cosmological parameters from the CMB intensity and polarization power spectra of the 2003 Antarctic flight of the BOOMERANG telescope. The BOOMERANG data alone constrains the parameters of the Λ\LambdaCDM model remarkably well and is consistent with constraints from a multi-experiment combined CMB data set. We add LSS data from the 2dF and SDSS redshift surveys to the combined CMB data set and test several extensions to the standard model including: running of the spectral index, curvature, tensor modes, the effect of massive neutrinos, and an effective equation of state for dark energy. We also include an analysis of constraints to a model which allows a CDM isocurvature admixture.Comment: 18 pages, 10 figures, submitted to Ap

    A Measurement of the Angular Power Spectrum of the CMB Temperature Anisotropy from the 2003 Flight of Boomerang

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    We report on observations of the Cosmic Microwave Background (CMB) obtained during the January 2003 flight of Boomerang . These results are derived from 195 hours of observation with four 145 GHz Polarization Sensitive Bolometer (PSB) pairs, identical in design to the four 143 GHz Planck HFI polarized pixels. The data include 75 hours of observations distributed over 1.84% of the sky with an additional 120 hours concentrated on the central portion of the field, itself representing 0.22% of the full sky. From these data we derive an estimate of the angular power spectrum of temperature fluctuations of the CMB in 24 bands over the multipole range (50 < l < 1500). A series of features, consistent with those expected from acoustic oscillations in the primordial photon-baryon fluid, are clearly evident in the power spectrum, as is the exponential damping of power on scales smaller than the photon mean free path at the epoch of last scattering (l > 900). As a consistency check, the collaboration has performed two fully independent analyses of the time ordered data, which are found to be in excellent agreement.Comment: 11 pages, 7 figures, 3 tables. High resolution figures and data are available at http://cmb.phys.cwru.edu/boomerang/ and http://oberon.roma1.infn.it/boomerang/b2

    Searching for non Gaussian signals in the BOOMERanG 2003 CMB maps

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    We analyze the BOOMERanG 2003 (B03) 145 GHz temperature map to constrain the amplitude of a non Gaussian, primordial contribution to CMB fluctuations. We perform a pixel space analysis restricted to a portion of the map chosen in view of high sensitivity, very low foreground contamination and tight control of systematic effects. We set up an estimator based on the three Minkowski functionals which relies on high quality simulated data, including non Gaussian CMB maps. We find good agreement with the Gaussian hypothesis and derive the first limits based on BOOMERanG data for the non linear coupling parameter f_NL as -300<f_NL<650 at 68% CL and -800<f_NL<1050 at 95% CL.Comment: accepted for publication in ApJ. Letter

    Subdegree Sunyaev-Zel'dovich Signal from Multifrequency BOOMERanG observations

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    The Sunyaev-Zel'dovich (SZ) effect is the inverse Compton-scattering of cosmic microwave background (CMB) photons by hot electrons in the intervening gas throughout the universe. The effect has a distinct spectral signature that allows its separation from other signals in multifrequency CMB datasets. Using CMB anisotropies measured at three frequencies by the BOOMERanG 2003 flight we constrain SZ fluctuations in the 10 arcmin to 1 deg angular range. Propagating errors and potential systematic effects through simulations, we obtain an overall upper limit of 15.3 uK (2 sigma) for rms SZ fluctuations in a broad bin between multipoles of of 250 and 1200 at the Rayleigh-Jeans (RJ) end of the spectrum. When combined with other CMB anisotropy and SZ measurements, we find that the local universe normalization of the density perturbations is sigma-8(SZ) < 0.96 at the 95% confidence level, consistent with sigma-8 determined from primordial perturbations.Comment: accepted for publication in ApJ. Letter

    Measuring CMB Polarization with BOOMERANG

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    BOOMERANG is a balloon-borne telescope designed for long duration (LDB) flights around Antarctica. The second LDB Flight of BOOMERANG took place in January 2003. The primary goal of this flight was to measure the polarization of the CMB. The receiver uses polarization sensitive bolometers at 145 GHz. Polarizing grids provide polarization sensitivity at 245 and 345 GHz. We describe the BOOMERANG telescope noting changes made for 2003 LDB flight, and discuss some of the issues involved in the measurement of polarization with bolometers. Lastly, we report on the 2003 flight and provide an estimate of the expected results.Comment: 12 pages, 8 figures, To be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive). Fixed typos, and reformatted citation

    B2K: The polarization-sensitive BOOMERanG experiment

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    We describe the new BOOMERanG payload, which is being prepared for a new circum-antarctic flight, with the aim to detect the linear polarization of the Cosmic Microwave Background (CMB). In addition to polarization capabilities, obtained by means of special bolometers, the instrument has been improved in the attitude reconstruction system and in the calibration system
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