Biological implications of high-energy cosmic ray induced muon flux in the extragalactic shock model

A ~ 62 My periodicity in fossil biodiversity has been observed in independent studies of paleontology databases over ~0.5Gy. The period and phase of this biodiversity cycle coincides with the oscillation of our solar system normal to the galactic disk with an amplitude ~70 parsecs and a period ~64 My. Our Galaxy is falling toward the Virgo cluster, forming a galactic shock at the north end of our galaxy due to this motion, capable of accelerating particles and exposing our galaxy's northern side to a higher flux of cosmic rays. These high-energy particles strike the Earth's atmosphere initiating extensive air showers, ionizing the atmosphere by producing charged secondary particles. Secondary particles such as muons produced as a result of nuclear interactions are able to reach the ground and enhance the biological radiation dose. Using a Monte Carlo simulation package CORSIKA, we compute the biological dose resulting from enhanced muon exposure from cosmic rays and discuss their implications for terrestrial biodiversity variations.Comment: Accepted for publication in Geophysical Research Letter

Comparison of Dynamical Approximation Schemes for Non-Linear Gravitational Clustering

I report on controlled comparison of gravitational approximation schemes linear/lognormal/adhesion/frozen-flow/Zel'dovich(ZA) and ZA's second--order generalization. In the last two cases we also created new versions of the approximation by truncation, i.e., by finding an optimum smoothing window (see text) for the initial conditions. The Zel'dovich approximation, with optimized initial smoothing, worked extremely well. Its second-order generalization was slightly better. The success of our best-choice was a result of the treatment of the phases of nonlinear Fourier components. The adhesion approximation produced the most accurate nonlinear power spectrum and density distribution, but its phase errors suggest mass condensations were moved somewhat incorrectly. Due to its better reproduction of the mass density distribution function and power spectrum, adhesion might be preferred for some uses. We recommend either n-body simulations or our modified versions of ZA, depending on the purpose. Modified ZA can rapidly generate large numbers of realizations of model universes with good accuracy down to galaxy group (or smaller) mass scales.Comment: 8 pp., plain TeX. ApJ Letters, in press. Contact [email protected] for Figure