Dipole distortions in the intergalactic medium

Baryonic feedback can significantly modify the spatial distribution of matter on small scales and create a bulk relative velocity between the dominant cold dark matter and the hot gas. We study the consequences of such bulk motions using two high-resolution hydrodynamic simulations, one with no feedback and one with very strong feedback. We find that relative velocities of order $100\ {\rm km}\, {\rm s}^{-1}$ are produced in the strong feedback simulation, whereas it is much smaller when there is no feedback. Such relative motions induce dipole distortions to the gas, which we quantify by computing the dipole correlation function. We find halo coordinates and velocities are systematically changed in the direction of the relative velocity. Finally, we discuss potential to observe the relative velocity via large-scale structure, Sunyaev–Zel’dovich and line emission measurements. Given the non-linear nature of this effect, it should next be studied in simulations with different feedback implementations/strengths to determine the available model space.

Dipole correlation effects on the local field and the effective dielectric constant in composite dielectrics containing high-k inclusions

Mixing dielectric polymers with high permittivity (high-k) inclusions can boost their actuation and energy storage properties.

Unified Impact Theory for Velocity-Changing Effects and Speed Dependencies in Neutral Species Lineshapes

A dipole correlation function which incorporates velocity-changing (motional narrowing) effects and the effects of speed-dependent Lorentz relaxation rates into otherwise Voigt profile correlation functions is developed, based partly upon previous work by the author. For the first time simple closed expressions, which lend themselves to elementary calculation beginning only with the relevant parts of intermolecular interaction energies, are developed for the cubic time-dependent term within the exponent describing the decay of the correlation function. This term is of first order in perturber number density, as are the Lorentz parameters, and is complex, thereby allowing for narrowing, changing in shape and asymmetry in the line profile. “Soft” and “hard” collisions play no explicit role, though both are variously present for each line. Quartic time dependencies are also discussed, though they are thought to be negligible in nonhydrogen molecular spectroscopy. Finally, some comments are added about a relevant technique for hydrogen spectra.