Electron-Positron Jets from a Critically Magnetized Black Hole

The curved spacetime surrounding a rotating black hole dramatically alters the structure of nearby electromagnetic fields. The Wald field which is an asymptotically uniform magnetic field aligned with the angular momentum of the hole provides a convenient starting point to analyze the effects of radiative corrections on electrodynamics in curved spacetime. Since the curvature of the spacetime is small on the scale of the electron's Compton wavelength, the tools of quantum field theory in flat spacetime are reliable and show that a rotating black hole immersed in a magnetic field approaching the quantum critical value of $B_k=m^2 c^3/(e\hbar) \approx 4.4 \times 10^{13}$~G $\approx 1.3\times10^{-11}$ cm$^{-1}$ is unstable. Specifically, a maximally rotating three-solar-mass black hole immersed in a magnetic field of $2.3 \times 10^{12}$~G would be a copious producer of electron-positron pairs with a luminosity of $3 \times 10^{52}$ erg s$^{-1}$.Comment: 10 pages, 6 figures, submitted to Phys. Rev.

Generalized iterated wreath products of symmetric groups and generalized rooted trees correspondence

Consider the generalized iterated wreath product $S_{r_1}\wr \ldots \wr S_{r_k}$ of symmetric groups. We give a complete description of the traversal for the generalized iterated wreath product. We also prove an existence of a bijection between the equivalence classes of ordinary irreducible representations of the generalized iterated wreath product and orbits of labels on certain rooted trees. We find a recursion for the number of these labels and the degrees of irreducible representations of the generalized iterated wreath product. Finally, we give rough upper bound estimates for fast Fourier transforms.Comment: 18 pages, to appear in Advances in the Mathematical Sciences. arXiv admin note: text overlap with arXiv:1409.060

The Otterbein Miscellany - Fall 1986

https://digitalcommons.otterbein.edu/miscellany/1005/thumbnail.jp

Unstable states in QED of strong magnetic fields

We question the use of stable asymptotic scattering states in QED of strong magnetic fields. To correctly describe excited Landau states and photons above the pair creation threshold the asymptotic fields are chosen as generalized Licht fields. In this way the off-shell behavior of unstable particles is automatically taken into account, and the resonant divergences that occur in scattering cross sections in the presence of a strong external magnetic field are avoided. While in a limiting case the conventional electron propagator with Breit-Wigner form is obtained, in this formalism it is also possible to calculate $S$-matrix elements with external unstable particles.Comment: Revtex, 7 pages. To appear in Phys. Rev. D53(2

Area-wide eradication of the invasive European grapevine moth Lobesia botrana in California, USA

17openBothIn the fall of 2009, the first confirmed North American detection of the European grapevine moth (EGVM) Lobesia botrana (Denis & Schiffermüller) occurred in Napa County, California, USA. Based on its status as a significant grape pest in other parts of the world, the establishment of EGVM in California presented significant production and export issues for grapes, as well as for other fresh market agricultural commodities. Over the following seven years, an intensive California state-wide survey and area-wide eradication campaign was undertaken in partnership with agricultural officials at local, state and federal levels, university scientists and the wine, table grape and raisin industries. These efforts resulted in a dramatic decline in moth captures in pheromone traps from over 100 000 moths in 2010, to one in 2014, and none in 2015. In August of 2016, eradication was declared for all previously infested areas in California. The decision to pursue the eradication effort was based on the limited host range and geographic area of the EGVM infestation, the availability of effective tools for monitoring and control, and the strong support of the affected grape production and export industries. The eradication campaign employed coordinated logistical, regulatory, and technical efforts that included: 1) state-wide-monitoring using a network of pheromone-baited traps and in field monitoring; these findings were recorded in a geographic information system that was used to regularly communicate survey results to programme officials; 2) an area-wide application of mating disruption dispensers to infested vineyards, including use in urban environments within infested zones; 3) implementation by coordinators of area-wide insecticide treatments with application timing determined by degree-day modelling for each infested region; 4) a robust regulatory programme that initiated and maintained a quarantine of infested areas that regulated movement of fruit, farming equipment and winery processing waste; 5) an extensive outreach programme to grape growers, wineries, pest control specialists and the public; 6) formation of a technical working group that provided recommendations to the operational programme. An extensive methods development effort supported the programme. This included developing enhanced detection methods for vineyards under mating disruption, testing efficacy and residual control of insecticides, testing mating disruption formulations, evaluating the impacts of winery processing methods on EGVM mortality, developing methods to determine the timing of the development of successive EGVM generations (or biofix) under California conditions to improve degree-day models, developing EGVM rearing methods, testing the quality of pheromone lures and trap monitoring; and a spatial analysis of trapping data to determine programme effectiveness and to analyse invasion pathwaysopenSimmons, G.S.; Varela, L.; Daugherty, M.; Cooper, M.; Lance, D.; Mastro, V.; Carde, R.T.; Lucchi, A.; Ioriatti, C.; Bagnoli, B.; Steinhauer, R.; Broadway, R.; Stone Smith, B.; Hoffman, K.; Clark, G.; Whitmer, D.; Johnson, R.Simmons, G.S.; Varela, L.; Daugherty, M.; Cooper, M.; Lance, D.; Mastro, V.; Carde, R.T.; Lucchi, A.; Ioriatti, C.; Bagnoli, B.; Steinhauer, R.; Broadway, R.; Stone Smith, B.; Hoffman, K.; Clark, G.; Whitmer, D.; Johnson, R

Magnetic Photon Splitting: the S-Matrix Formulation in the Landau Representation

Calculations of reaction rates for the third-order QED process of photon splitting in strong magnetic fields traditionally have employed either the effective Lagrangian method or variants of Schwinger's proper-time technique. Recently, Mentzel, Berg and Wunner (1994) presented an alternative derivation via an S-matrix formulation in the Landau representation. Advantages of such a formulation include the ability to compute rates near pair resonances above pair threshold. This paper presents new developments of the Landau representation formalism as applied to photon splitting, providing significant advances beyond the work of Mentzel et al. by summing over the spin quantum numbers of the electron propagators, and analytically integrating over the component of momentum of the intermediate states that is parallel to field. The ensuing tractable expressions for the scattering amplitudes are satisfyingly compact, and of an appearance familiar to S-matrix theory applications. Such developments can facilitate numerical computations of splitting considerably both below and above pair threshold. Specializations to two regimes of interest are obtained, namely the limit of highly supercritical fields and the domain where photon energies are far inferior to that for the threshold of single-photon pair creation. In particular, for the first time the low-frequency amplitudes are simply expressed in terms of the Gamma function, its integral and its derivatives. In addition, the equivalence of the asymptotic forms in these two domains to extant results from effective Lagrangian/proper-time formulations is demonstrated.Comment: 19 pages, 3 figures, REVTeX; accepted for publication in Phys. Rev.

Very-high-energy gamma radiation associated with the unshocked wind of the Crab pulsar

We show that the relativistic wind in the Crab pulsar, which is commonly thought to be invisible in the region upstream of the termination shock at R < 0.1 pc, in fact could be directly observed through its inverse Compton gamm-ray emission. The search for such specific component of radiation in the gamma-ray spectrum of the Crab can provide unique information about the unshocked pulsar wind that is not accessible at other wavelengths.Comment: 11 pages, 11 figures, to appear in one of the April issues of MNRA

Prospects for Observations of Pulsars and Pulsar Wind Nebulae with CTA

The last few years have seen a revolution in very-high gamma-ray astronomy (VHE; E>100 GeV) driven largely by a new generation of Cherenkov telescopes (namely the H.E.S.S. telescope array, the MAGIC and MAGIC-II large telescopes and the VERITAS telescope array). The Cherenkov Telescope Array (CTA) project foresees a factor of 5 to 10 improvement in sensitivity above 0.1 TeV, extending the accessible energy range to higher energies up to 100 TeV, in the Galactic cut-off regime, and down to a few tens GeV, covering the VHE photon spectrum with good energy and angular resolution. As a result of the fast development of the VHE field, the number of pulsar wind nebulae (PWNe) detected has increased from one PWN in the early '90s to more than two dozen firm candidates today. Also, the low energy threshold achieved and good sensitivity at TeV energies has resulted in the detection of pulsed emission from the Crab Pulsar (or its close environment) opening new and exiting expectations about the pulsed spectra of the high energy pulsars powering PWNe. Here we discuss the physics goals we aim to achieve with CTA on pulsar and PWNe physics evaluating the response of the instrument for different configurations.Comment: accepted for publication in Astroparticle Physic