Effect of Our Galaxy's Motion on Weak Lensing Measurements of Shear and Convergence

In this work we investigate the effect on weak-lensing shear and convergence measurements due to distortions from the Lorentz boost induced by our Galaxy's motion. While no ellipticity is induced in an image from the Lorentz boost to first order in beta = v/c, the image is magnified. This affects the inferred convergence at a 10 per cent level, and is most notable for low multipoles in the convergence power spectrum C {\kappa}{\kappa} and for surveys with large sky coverage like LSST and DES. Experiments which image only small fractions of the sky and convergence power spectrum determinations at l > 5 can safely neglect the boost effect to first order in beta.Comment: 4 pages, replaced to reflect changes made for publication to MNRA

First second of leptons

A poorly constrained parameter in the Standard Model of Cosmology is the lepton asymmetry l = \sum_f l_f=\sum_f(n_f+n_{\nu_f})/s. Each flavour asymmetry l_f with f=e, \mu, {\tau} is the sum of the net particle density of the charged leptons n_f and their corresponding neutrinos, normalized with the entropy density s. Constraints on l_f \leq O(0.1) from BBN and CMB allow for lepton flavour asymmetries orders of magnitudes larger then the baryon asymmetry b ~ 10^{-10}. In this article we show how such large lepton (flavour) asymmetries influence the early universe, in particular the freeze out of WIMPs and the cosmic QCD transition.Comment: 4 pages, 2 figures; prepared for the 12th international conference on Topics in Astroparticle and Underground Physics, TAUP2011. v2: matches accepted versio

Large-angle anomalies in the CMB

We review the recently found large-scale anomalies in the maps of temperature anisotropies in the cosmic microwave background. These include alignments of the largest modes of CMB anisotropy with each other and with geometry and direction of motion of the Solar System, and the unusually low power at these largest scales. We discuss these findings in relation to expectation from standard inflationary cosmology, their statistical significance, the tools to study them, and the various attempts to explain them.Comment: Review in the Advances in Astronomy special issue "Testing the Gaussianity and Statistical Isotropy of the Universe" (eds. D. Huterer, E. Komatsu and S. Shandera); 16 pages, 7 figures. v2 matches the published versio

Is the low-l microwave background cosmic?

The large-angle (low-l) correlations of the Cosmic Microwave Background exhibit several statistically significant anomalies compared to the standard inflationary big-bang model, however no connection has hitherto been drawn between them. Here we show that the quadrupole and octopole are far more correlated (99.97% C.L.) than previously thought. The quadrupole plane and the three octopole planes are remarkably aligned. Three of these planes are orthogonal to the ecliptic at a level inconsistent with gaussian random statistically isotropic skies at 99.8% C.L., and the normals to these planes are aligned at 99.9% C.L. with the direction of the cosmological dipole and with the equinoxes. The remaining octopole plane is orthogonal to the supergalactic plane at >99.9% C.L. In a combined quadrupole-octopole map, the ecliptic plane narrowly threads between a hot spot and a cold spot over approximately 1/3 of the sky, and separates the three strongest extrema (in the south ecliptic hemisphere) from the three weakest extrema (in the north ecliptic hemisphere).Comment: 4 pages, 3 figures; more figures available at: http://www.phys.cwru.edu/projects/mpvectors/ PRL in press versio

Real Space Approach to CMB deboosting

The effect of our Galaxy's motion through the Cosmic Microwave Background rest frame, which aberrates and Doppler shifts incoming photons measured by current CMB experiments, has been shown to produce mode-mixing in the multipole space temperature coefficients. However, multipole space determinations are subject to many difficulties, and a real-space analysis can provide a straightforward alternative. In this work we describe a numerical method for removing Lorentz- boost effects from real-space temperature maps. We show that to deboost a map so that one can accurately extract the temperature power spectrum requires calculating the boost kernel at a finer pixelization than one might naively expect. In idealized cases that allow for easy comparison to analytic results, we have confirmed that there is indeed mode mixing among the spherical harmonic coefficients of the temperature. We find that using a boost kernel calculated at Nside=8192 leads to a 1% bias in the binned boosted power spectrum at l~2000, while individual Cls exhibit ~5% fluctuations around the binned average. However, this bias is dominated by pixelization effects and not the aberration and Doppler shift of CMB photons that causes the fluctuations. Performing analysis on maps with galactic cuts does not induce any additional error in the boosted, binned power spectra over the full sky analysis. For multipoles that are free of resolution effects, there is no detectable deviation between the binned boosted and unboosted spectra. This result arises because the power spectrum is a slowly varying function of and does not show that, in general, Lorentz boosts can be neglected for other cosmological quantities such as polarization maps or higher-point functions.Comment: 8 pages, submitted to MNRA