576 research outputs found

    Using Big Bang Nucleosynthesis to Extend CMB Probes of Neutrino Physics

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    We present calculations showing that upcoming Cosmic Microwave Background (CMB) experiments will have the power to improve on current constraints on neutrino masses and provide new limits on neutrino degeneracy parameters. The latter could surpass those derived from Big Bang Nucleosynthesis (BBN) and the observationally-inferred primordial helium abundance. These conclusions derive from our Monte Carlo Markov Chain (MCMC) simulations which incorporate a full BBN nuclear reaction network. This provides a self-consistent treatment of the helium abundance, the baryon number, the three individual neutrino degeneracy parameters and other cosmological parameters. Our analysis focuses on the effects of gravitational lensing on CMB constraints on neutrino rest mass and degeneracy parameter. We find for the PLANCK experiment that total (summed) neutrino mass Mν>0.29M_{\nu} > 0.29 eV could be ruled out at 2σ2\sigma or better. Likewise neutrino degeneracy parameters ξνe>0.11\xi_{\nu_{e}} > 0.11 and ∣ξνμ/τ∣>0.49| \xi_{\nu_{\mu/\tau}} | > 0.49 could be detected or ruled out at 2σ2\sigma confidence, or better. For POLARBEAR we find that the corresponding detectable values are Mν>0.75eVM_\nu > 0.75 {\rm eV}, ξνe>0.62\xi_{\nu_{e}} > 0.62, and ∣ξνμ/τ∣>1.1| \xi_{\nu_{\mu/\tau}}| > 1.1, while for EPIC we obtain Mν>0.20eVM_\nu > 0.20 {\rm eV}, ξνe>0.045\xi_{\nu_{e}} > 0.045, and ∣ξνμ/τ∣>0.29|\xi_{\nu_{\mu/\tau}}| > 0.29. Our forcast for EPIC demonstrates that CMB observations have the potential to set constraints on neutrino degeneracy parameters which are better than BBN-derived limits and an order of magnitude better than current WMAP-derived limits.Comment: 27 pages, 11 figures, matches published version in JCA

    CMB Polarization Systematics Due to Beam Asymmetry: Impact on Cosmological Birefringence

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    The standard cosmological model is assumed to respect parity symmetry. Under this assumption the cross-correlations of the CMB's temperature anisotropy and `gradient'-like polarization, with the `curl'-like polarization identically vanish over the full sky. However, extensions of the standard model which allow for light scalar field or axion coupling to the electromagnetic field, or coupling to the Riemann gravitational field-strength, as well as other modifications of field theories, may induce a rotation of the CMB polarization plane on cosmological scales and manifest itself as nonvanishing TB and EB cross-correlations. Recently, the degree of parity violation (reflected in polarization rotation) was constrained using data from BOOMERANG, WMAP and QUAD. Forecasts have been made for near-future experiments (e.g. PLANCK) to further constrain parity- and Lorentz-violating terms in the fundamental interactions of nature. Here we consider a real-world effect induced by a class of telescope beam systematics which can mimic the rotation of polarization plane or otherwise induce nonvanishing TB and EB correlations. In particular, adopting the viewpoint that the primary target of future experiments will be the inflationary B-mode signal, we assume the beam-systematics of the upcoming PLANCK and POLARBEAR experiments are optimized towards this goal, and explore the implications of the allowed levels of beam systematics on the resulting precision of polarization-rotation measurements.Comment: 9 pages. Minor typos corrected. Matches published version in PRD Vol. 79 No. 1

    The Effects of Game Size on the Physical Activity Levels and Ball Touches of Elementary School Children in Physical Education

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    The purpose of this study was to determine the impact of participating in small (3v3), medium (6v6), and large-sided (12v12) games on the physical activity levels (pedometer step counts, accelerometer counts, and minutes of moderate-to-vigorous physical activity) and ball touches of children in physical education class. Participants were 29 students (55% boys and 45% girls) age 10-11 yrs. All participants wore a Yamax SW-200 pedometer and had their ball touches monitored and recorded. Twelve participants also wore an ActiGraph GT3X accelerometer. Repeated measure ANOVAs were computed to test for significant differences for each dependant variable with corresponding post hoc tests. Results indicated the 3v3 and 6v6 game conditions yielded significantly higher accelerometer counts and ball touches than the 12v12 condition. The 3v3 game condition also produced significantly higher ball touches than the 6v6 condition. These findings highlight the importance of utilizing smaller-sided games in physical education to promote increased involvement and physical activity

    Revealing Cosmic Rotation

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    Cosmological Birefringence (CB), a rotation of the polarization plane of radiation coming to us from distant astrophysical sources, may reveal parity violation in either the electromagnetic or gravitational sectors of the fundamental interactions in nature. Until only recently this phenomenon could be probed with only radio observations or observations at UV wavelengths. Recently, there is a substantial effort to constrain such non-standard models using observations of the rotation of the polarization plane of cosmic microwave background (CMB) radiation. This can be done via measurements of the BB-modes of the CMB or by measuring its TB and EB correlations which vanish in the standard model. In this paper we show that EBEB correlations-based estimator is the best for upcoming polarization experiments. The EBEB based estimator surpasses other estimators because it has the smallest noise and of all the estimators is least affected by systematics. Current polarimeters are optimized for the detection of BB-mode polarization from either primordial gravitational waves or by large scale structure via gravitational lensing. In the paper we also study optimization of CMB experiments for the detection of cosmological birefringence, in the presence of instrumental systematics, which by themselves are capable of producing EBEB correlations; potentially mimicking CB.Comment: 10 pages, 3 figures, 2 table

    Constraints on the Neutrino Mass from SZ Surveys

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    Statistical measures of galaxy clusters are sensitive to neutrino masses in the sub-eV range. We explore the possibility of using cluster number counts from the ongoing PLANCK/SZ and future cosmic-variance-limited surveys to constrain neutrino masses from CMB data alone. The precision with which the total neutrino mass can be determined from SZ number counts is limited mostly by uncertainties in the cluster mass function and intracluster gas evolution; these are explicitly accounted for in our analysis. We find that projected results from the PLANCK/SZ survey can be used to determine the total neutrino mass with a (1\sigma) uncertainty of 0.06 eV, assuming it is in the range 0.1-0.3 eV, and the survey detection limit is set at the 5\sigma significance level. Our results constitute a significant improvement on the limits expected from PLANCK/CMB lensing measurements, 0.15 eV. Based on expected results from future cosmic-variance-limited (CVL) SZ survey we predict a 1\sigma uncertainty of 0.04 eV, a level comparable to that expected when CMB lensing extraction is carried out with the same experiment. A few percent uncertainty in the mass function parameters could result in up to a factor \sim 2-3 degradation of our PLANCK and CVL forecasts. Our analysis shows that cluster number counts provide a viable complementary cosmological probe to CMB lensing constraints on the total neutrino mass.Comment: Replaced with a revised version to match the MNRAS accepted version. arXiv admin note: text overlap with arXiv:1009.411

    Cosmic Microwave Background Temperature at Galaxy Clusters

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    We have deduced the cosmic microwave background (CMB) temperature in the Coma cluster (A1656, z=0.0231z=0.0231), and in A2163 (z=0.203z=0.203) from spectral measurements of the Sunyaev-Zel'dovich (SZ) effect over four passbands at radio and microwave frequencies. The resulting temperatures at these redshifts are TComa=2.789−0.065+0.080T_{Coma} = 2.789^{+0.080}_{-0.065} K and TA2163=3.377−0.102+0.101T_{A2163} = 3.377^{+0.101}_{-0.102} K, respectively. These values confirm the expected relation T(z)=T0(1+z)T(z)=T_{0}(1+z), where T0=2.725±0.002T_{0}= 2.725 \pm 0.002 K is the value measured by the COBE/FIRAS experiment. Alternative scaling relations that are conjectured in non-standard cosmologies can be constrained by the data; for example, if T(z)=T0(1+z)1−aT(z) = T_{0}(1+z)^{1-a} or T(z)=T0[1+(1+d)z]T(z)=T_{0}[1+(1+d)z], then a=−0.16−0.32+0.34a=-0.16^{+0.34}_{-0.32} and d=0.17±0.36d = 0.17 \pm 0.36 (at 95% confidence). We briefly discuss future prospects for more precise SZ measurements of T(z)T(z) at higher redshifts.Comment: 13 pages, 1 figure, ApJL accepted for publicatio
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