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Title: Solution to the Cosmic Ray Anisotropy Problem

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 114; Journal Issue: 2; Journal ID: ISSN 0031-9007
American Physical Society
Country of Publication:
United States

Citation Formats

Mertsch, Philipp, and Funk, Stefan. Solution to the Cosmic Ray Anisotropy Problem. United States: N. p., 2015. Web. doi:10.1103/PhysRevLett.114.021101.
Mertsch, Philipp, & Funk, Stefan. Solution to the Cosmic Ray Anisotropy Problem. United States. doi:10.1103/PhysRevLett.114.021101.
Mertsch, Philipp, and Funk, Stefan. 2015. "Solution to the Cosmic Ray Anisotropy Problem". United States. doi:10.1103/PhysRevLett.114.021101.
title = {Solution to the Cosmic Ray Anisotropy Problem},
author = {Mertsch, Philipp and Funk, Stefan},
abstractNote = {},
doi = {10.1103/PhysRevLett.114.021101},
journal = {Physical Review Letters},
number = 2,
volume = 114,
place = {United States},
year = 2015,
month = 1

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevLett.114.021101

Citation Metrics:
Cited by: 17works
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Web of Science

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  • Bouncing cosmologies are often proposed as alternatives to standard inflation for the explanation of the homogeneity and flatness of the universe. In such scenarios, the present cosmological expansion is preceded by a contraction phase. However, during the contraction, in general the anisotropy of the universe grows and eventually leads to a chaotic mixmaster behavior. This would either be hard to reconcile with observations or even lead to a singularity instead of the bounce. In order to preserve a smooth and isotropic bounce, the source for the contraction must have a super-stiff equation of state with P/ρ = w > 1.more » In this letter we propose a new mechanism to solve the anisotropy problem for any low-energy value of w by arguing that high energy physics leads to a modification of the equation of state, with the introduction of non-linear terms. In such a scenario, the anisotropy is strongly suppressed during the high energy phase, allowing for a graceful isotropic bounce, even when the low-energy value of w is smaller than unity.« less
  • An analytical solution to a model of the modulation of galactic cosmic rays in the presence of particle drifts is presented and discussed. The solution assumes an energy-independent radial diffusion coefficient kappa/sub rr/ proportional to r and no latitudinal diffusion, and includes energy-independent particle drift velocities v/sub D/, which are similar to those expected in a Parker spiral magnetic field with an equatorial current sheet. The solutions clearly demonstrate the large effects of drifts on the modulated cosmic ray intensity. For values of kappa/sub rr/ and v/sub D/ which are plausible for 1 GV rigidity protons, the logarithmic radial gradientmore » in the inner solar system is reduced by more than a factor of 5 over the value calculated in the absence of drifts. We find that even for much smaller values of v/sub D/ and kappa/sub rr/, such as might be expected for approx.10 MeV protons, the effects of the drifts can be substantial.« less
  • Increasing evidence suggests that most of the energy density of the universe consists of a dark energy component with negative pressure that causes the cosmic expansion to accelerate. We address why this component comes to dominate the universe only recently. We present a class of theories based on an evolving scalar field where the explanation is based entirely on internal dynamical properties of the solutions. In the theories we consider, the dynamics causes the scalar field to lock automatically into a negative pressure state at the onset of matter domination such that the present epoch is the earliest possible timemore » consistent with nucleosynthesis restrictions when it can start to dominate.« less
  • We cross-correlate the cosmic microwave background (CMB) temperature anisotropy maps from the Wilkinson Microwave Anisotropy Probe (WMAP), MAXIMA-1, and MAXIMA-2 experiments. We use the cross spectrum, which is the spherical harmonic transform of the angular two-point correlation function, to quantify the correlation as a function of angular scale. We find that the three possible pairs of cross spectra are in close agreement with each other and with the power spectra of the individual maps. The probability that there is no correlation between the maps is smaller than 1 x 10(-8). We also calculate power spectra for maps made of differencesmore » between pairs of maps and show that they are consistent with no signal. The results conclusively show that the three experiments not only display the same statistical properties of the CMB anisotropy, but also detect the same features wherever the observed sky areas overlap. We conclude that the contribution of systematic errors to these maps is negligible and that MAXIMA and WMAP have accurately mapped the CMB anisotropy.« less