Circumstellar Interaction Around Type Ib/c Supernovae and the GRB Connection

Radio observations of Type Ib/c supernovae suggest that circumstellar interaction takes place with a wide range of wind densities, comparable to that seen in Galactic Wolf-Rayet stars. Efficient production of magnetic field in the shocked region is needed. The X-ray emission observed from some Type Ib/c supernovae is higher than would be expected by the thermal or inverse Compton mechanisms; a synchrotron interpretation requires a flattening of the electron energy spectrum at high energies, as might occur in a cosmic ray dominated shock wave. The wind density variations that are indicated in two supernovae may be due to a binary companion, although variable mass loss from a single star remains a possibility. Other than the optical supernova radiation, the emission from the nearby SN 2006aj/GRB 060218 appears to be powered by a central engine, while that from SN 1998bw/GRB 980425 could be powered by either a central engine or the outer supernova ejecta.Comment: 8 pages, to appear in Circumstellar Media and Late Stages of Massive Stellar Evolution, RevMexA

Neutrinos as a Diagnostic of High Energy Astrophysical Processes

A leading candidate for the extragalactic source of high energy cosmic rays is the Fermi engine mechanism, in which protons confined by magnetic fields are accelerated to very high energy through repeated scattering by plasma shock fronts. In the process of acceleration, collisions of trapped protons with the ambient plasma produce pions which decay to electromagnetic energy and neutrinos. For optically thin sources, a strong connection between the emerging cosmic rays and secondary neutrinos can be established. In this context, we show the feasibility of using the Glashow resonance as a discriminator between the $pp$ and $p\gamma$ interactions in Fermi engines as sources of neutrinos. In particular, we demonstrate how three years of observation at the km$^3$ IceCube facility can serve as a filter for the dominance of the $pp$ interaction at the source.Comment: The previous version of this paper contained a brief discussion of how the flux of neutrinos from optically thin sources can be used as a marker of the cosmic ray Galactic/extra-galactic transition. This topic has received detailed discussion in a separate paper, arXiv:astro-ph/050322

Punitive Damages - Strict Products Liability - \u3cem\u3eErie\u3c/em\u3e Doctrine

The Pennsylvania Supreme Court has affirmed that punitive damages are not available to a plaintiff in a strict products liability action in Pennsylvania, raising an Erie doctrine conflict with decisions by Federal District Courts sitting in Pennsylvania. Martin v. Johns-Manville Corp., 508 Pa. 154, 494 A.2d 1088 (1985)

Probing QCD approach to thermal equilibrium with ultrahigh energy cosmic rays

The Pierre Auger Collaboration has reported an excess in the number of muons of a few tens of percent over expectations computed using extrapolation of hadronic interaction models tuned to accommodate LHC data. Very recently, we proposed an explanation for the muon excess assuming the formation of a deconfined quark matter (fireball) state in central collisions of ultrarelativistic cosmic rays with air nuclei. At the first stage of its evolution the fireball contains gluons as well as $u$ and $d$ quarks. The very high baryochemical potential inhibits gluons from fragmenting into $u \bar u$ and $d \bar d$, and so they fragment predominantly into $s \bar s$ pairs. In the hadronization which follows this leads to the strong suppression of pions and hence photons, but allows heavy hadrons to be emitted carrying away strangeness. In this manner, the extreme imbalance of hadron to photon content provides a way to enhance the muon content of the air shower. In this communication we study theoretical systematics from hadronic interaction models used to describe the cascades of secondary particles produced in the fireball explosion. We study the predictions of one of the leading LHC-tuned models QGSJET II-04 considered in the Auger analysis.Comment: 7 pages LaTeX, 6 .pdf figure