• Journal of The Korean Astronomical Society
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• v.48 no.2
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• pp.155-164
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• 2015

In Kang (2015) we calculated the acceleration of cosmic-ray electrons at weak spherical shocks that are expected to form in the cluster outskirts, and estimated the diffuse synchrotron radiation emitted by those electrons. There we demonstrated that, at decelerating spherical shocks, the volume integrated spectra of both electrons and radiation deviate significantly from the test-particle power-laws predicted for constant planar shocks, because the shock compression ratio and the flux of inject electrons decrease in time. In this study, we consider spherical blast waves propagating through a constant density core surrounded by an isothermal halo with ρ ∝ r⁻ⁿ in order to explore how the deceleration of the shock affects the radio emission from accelerated electrons. The surface brightness profile and the volumeintegrated radio spectrum of the model shocks are calculated by assuming a ribbon-like shock surface on a spherical shell and the associated downstream region of relativistic electrons. If the postshock magnetic field strength is about 0.7 or 7 µG, at the shock age of ∼ 50 Myr, the volume-integrated radio spectrum steepens gradually with the spectral index from α_inj to α_inj + 0.5 over 0.1–10 GHz, where α_inj is the injection index at the shock position expected from the diffusive shock acceleration theory. Such gradual steepening could explain the curved radio spectrum of the radio relic in cluster A2266, which was interpreted as a broken power-law by Trasatti et al. (2015), if the relic shock is young enough so that the break frequency is around 1 GHz.

• Journal of English Language & Literature
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• v.57 no.6
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• pp.939-958
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• 2011

Ezra Pound has an idea of poetry as a field of energy in which words interact with each other with kinetic energy. The energy field which Pound creates in his poem is analogous to the theory of electromagnetism developed by Michael Faraday and James Maxwell, who look upon the space around magnets, electric charges and currents not as empty but as filled with energy and activity. Pound argues that "words are charged with force like electricity," demonstrating that words charged with their own images or energies of positive or negative valence interact one another. This idea is similar to Faraday's concept of "line of force" which he used to represent the disposition of electric and magnetic forces in space. Pound's concept of "image" as an "intellectual and emotional complex in an instant" is remarkably consonant with the confluence of electric and magnetic fields that are coupled to each other as they travel through space in the form of electromagnetic waves. The instant profusion of conception and perception, much like that of electric and magnetic fields, enables Pound to move beyond the sequential and linear hierarchy in time and space. Particularly, Maxwell's stunning discovery that the electromagnetic waves propagate in space at 'the speed of light' has allowed Pound a relativistic sense of escape from the limitations of Newtonian absolute time and space. Pound's poetry transcends any geographical space and sequential time by rendering and juxtaposing images simultaneously. Pound was fully aware of light and electricity fundamental to what he called his world "the electric world." Pound's experiments in Imagism and Vorticism can be considered an attempt to rediscover a place for poetry in the modern world of science and technology. Almost all the appliances that we think of today as modern were laid down in the closing decades of the 19th century and the first decades of the 20th century, in response to the availability of electromagnetic energy. This paper explores how Pound responded to the age of modern technology and science, examining his conception of "image" through his many analogies and similes drawn from electromagnetism. Pound's imagist poetics and poetry come to embody, not only the characteristics of the electric age in the early twentieth century, but the principles of electromagnetism the electric age is based upon.