Imaging sub-milliarcsecond stellar features with intensity interferometry using air Cherenkov telescope arrays

Recent proposals have been advanced to apply imaging air Cherenkov telescope arrays to stellar intensity interferometry (SII). Of particular interest is the possibility of model-independent image recovery afforded by the good (u, v)-plane coverage of these arrays, as well as recent developments in phase retrieval techniques. The capabilities of these instruments used as SII receivers have already been explored for simple stellar objects, and here the focus is on reconstructing stellar images with non-uniform radiance distributions. We find that hot stars (T > 6000 K) containing hot and/or cool localized regions (T \sim 500 K) as small as \sim 0.1 mas can be imaged at short wavelengths ({\lambda} = 400 nm).Comment: Accepted for publication in MNRAS. 6 pages, 10 figure

Doctor of Philosophy

dissertationWe study the effects of spatial dispersion in disordered noncentrosymmetric metals. Specifically, we consider the kinetic magnetoelectric effect, and natural optical activity of metals, as well as the so-called dynamic chiral magnetic effect as a particular case of natural optical activity. These effects stem from the magnetic moments of quasiparticles near the Fermi surface. In addition to the well-known intrinsic contribution, we identify new disorder-induced extrinsic contributions to these magnetic moments that come from the skew-scattering and side-jump processes, familiar from the theory of the anomalous Hall effect. We show that at low frequencies the spatial dispersion of the conductivity tensor comes mainly from either the skew-scattering or intrinsic contribution, and there is always a region of frequencies in which the intrinsic mechanism dominates. However, our results imply that in clean three-dimensional metals, the kinetic magnetoelectric effect is in general determined by impurity skew scattering, rather than intrinsic contributions. Further, we study the kinetic magnetoelectric effect in three-dimensional conductors, specializing to the case of p-doped trigonal tellurium. We include both the intrinsic and extrinsic contributions to the effect, which stem from the band structure of the crystal, and from disorder scattering, respectively. Specifically, we determine the dependence of the kinetic magnetoelectric response on the hole doping in tellurium, and show that the intrinsic effects dominate for low levels of doping while extrinsic effects, in particular the skew-scattering mechanism, dominate for high levels of doping. The results of this work imply that three-dimensional helical metals are promising candidates for spintronics applications and in particular, they can provide robust control over current-induced magnetic torques

Monte-Carlo simulation of stellar intensity interferometry

honors thesisCollege of SciencePhysics & AstronomyStephan LeBohecStellar intensity interferometers will allow for achieving stellar imaging with a tenth of a milli-arcsecond resolution in the optical band by taking advantage of the large light collecting area and broad range of inter-telescope distances offered by future gamma-ray Air Cherenkov Telescope (ACT) arrays. Up to now, studies characterizing the capabilities of ACTs used as intensity interferometers have not accounted for certain realistic effects that will be encountered when collecting actual data. In this paper, we present the semi-classical quantum optics Monte-Carlo simulation we developed in order to investigate these experimental limitations. Using this tool we present our first results using our simulation model to investigate sensitivity and imaging capability limitations associated with telescopes spatial extension, photodetectors and electronics pulse shape, and excess noise