The WIMP capture process for dark stars in the early universe

The first stars to form in the universe may have been dark stars, powered by dark matter annihilation instead of nuclear fusion. The initial amount of dark matter gathered by the star gravitationally can sustain it only for a limited period of time. It has been suggested that capture of additional dark matter from the environment can prolong the dark star phase even to the present day. Here we show that this capture process is ineffective to prolong the life of the first generation of dark stars. We construct a Monte-Carlo simulation that follows each Weakly Interacting Massive Particle (WIMP) in the dark matter halo as its orbit responds to the formation and evolution of the dark star, as it scatters off the star's nuclei, and as it annihilates inside the star. A rapid depletion of the WIMPs on orbits that cross the star causes the demise of the first generation of dark stars. We suggest that a second generation of dark stars may in principle survive much longer through capture. We comment on the effect of relaxing our assumptions.Comment: 13 pages, 6 figure

New State Records for the Cicada Parasite Beetle Sandalus petrophya Knoch (Rhipiceridae)

Abstract: New state records are presented for Sandalus petrophya specimens from Nebraska and Iowa along with the currently known distribution of this beetle species

Trawl-induced Damage to Sponges Observed From a Research Submersible

Three experimental trawl paths subjected to a single pass with the trawl in 1996 in about 200 m of water on the eastern Gulf of Alaska continental shelf were revisited in July 1997, 1 year post-trawl. Many large, erect sponges, the taxa impacted most significantly, had been removed or damaged by the trawl. Sponges in the cold, deep water of the Gulf of Alaska were slow to recover from trawling effects. These findings contrast with recovery times for shallow, warmwater sponges and may have fishery management implications for cold-water regions

Review of Observational Evidence for Dark Matter in the Universe and in upcoming searches for Dark Stars

Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed: rotation curves of galaxies, weak lensing measurements, hot gas in clusters, primordial nucleosynthesis and microwave background experiments. In addition, a new line of research on Dark Stars is presented, which suggests that the first stars to exist in the universe were powered by dark matter heating rather than by fusion: the observational possibilities of discovering dark matter in this way are discussed.Comment: 14 pages, 7 figures, Conference Proceeding for "Dark Matter and Dark Energy" in Lyon, France, July 200

Distribution of \u3ci\u3eStrongylium Crenatum\u3c/i\u3e (Coleoptera: Tenebrionidae) in the United States and First Record From Iowa

Strongylium crenatum Mäklin (Coleoptera: Tenebrionidae) is reported from Iowa for the first time. After discovering that Iowa represented a large range extension for this species, label data were collected to update its range. Numerous insect collections and references were checked and specimens representing 17 states were located

New State Records for \u3ci\u3ePerillus Strigipes\u3c/i\u3e (Heteroptera: Pentatomidae: Asopinae)

The stink bug Perillus strigipes is reported from Alabama, Iowa, Kansas, Louisiana, Maine, and Mississippi for the first time. This insect species has a wide distribution but generally is seldom collected

Generalized Cardassian Expansion: Models in Which the Universe is Flat, Matter Dominated, and Accelerating

The Cardassian universe is a proposed modification to the Friedmann Robertson Walker (FRW) equation in which the universe is flat, matter dominated, and accelerating. Here we generalize the original Cardassian proposal to include additional variants on the FRW equation. Specific examples are presented. In the ordinary FRW equation, the right hand side is a linear function of the energy density, $H^2 \sim \rho$. Here, instead, the right hand side of the FRW equation is a different function of the energy density, $H^2 \sim g(\rho)$. This function returns to ordinary FRW at early times, but modifies the expansion at a late epoch of the universe. The only ingredients in this universe are matter and radiation: in particular, there is {\it no} vacuum contribution. Currently the modification of the FRW equation is such that the universe accelerates. The universe can be flat and yet consist of only matter and radiation, and still be compatible with observations. The energy density required to close the universe is much smaller than in a standard cosmology, so that matter can be sufficient to provide a flat geometry. The modifications may arise, e.g., as a consequence of our observable universe living as a 3-dimensional brane in a higher dimensional universe. The Cardassian model survives several observational tests, including the cosmic background radiation, the age of the universe, the cluster baryon fraction, and structure formation. As will be shown in future work, the predictions for observational tests of the generalized Cardassian models can be very different from generic quintessence models, whether the equation of state is constant or time dependent.Comment: 5 pages, Conference Proceeding, Meeting on Sources and Detection of Dark Matter and Dark Energy in the Universe, Marina del Rey, CA, February 200

Review of Statistics with Stata (Updated for Version 7)

The new book by Hamilton (2002) is reviewed. Copyright 2002 by Stata Corporation.