Two families of elliptical plasma lenses

Abstract

Plasma lensing is the refraction of low-frequency electromagnetic rays due to free electrons in the interstellar medium. Although the phenomenon has a distinct similarity to gravitational lensing, particularly in its mathematical description, plasma lensing introduces other additional features, such as wavelength dependence, radial rather than tangential image distortions, and strong demagnification of background sources. Axisymmetrical models of plasma lenses have been well-studied in the literature, but density distributions with more complicated shapes can provide new and exotic image configurations and increase the richness of the magnification properties. As a first step towards non-axisymmetrical distributions, we study two families of elliptical plasma lens, softened power-law and exponential plasma distributions. We perform numerical studies on each lens model, and present them over a parameter space. In addition to deriving elliptical plasma lens formulae, we also investigate the number of critical curves that the lens can produce by studying the lens parameter space, in particular the dependence on the lensing ellipticity. We find that the introduction of ellipticity into the plasma distribution can enhance the lensing effects as well as the complexity of the magnification map.

The physics of fast radio bursts

“…The electron density distribution on the lens plane will influence the deflection angle to a great extent and different lens models have been developed. The most commonlyadopted model is one-dimension Gaussian lens [50,52] and more complicated light curves can be realized if other lens models are assumed [53,54].…”

Deflection of light rays by spherically symmetric black hole in dispersive medium

“…Substituting p 2 ϕ from ( 31) into (33), we find that the equation for the radius of a circular light orbit can be compactified to the following simple form:…”

“…In a recent paper [30], we have investigated gravitational microlensing in the presence of plasma ('hill-hole' effect). For some other recent studies see [31][32][33][34][35][36][37][38]. Recent review of plasma effects in gravitational lensing can be found in [39].…”

Hills and holes in the microlensing light curve due to plasma environment around gravitational lens

“…In contrast to the converging achromatic behaviour of the vacuum gravitational lenses, the frequency-dependent lensing occurs from the refraction of electromagnetic rays by the plasma along an observer's line of sight and has the diverging character for spherically symmetric distributions with falling density. Such plasma lensing has been recently studied numerically by methods of gravitational lens formalism in series of works of Er & Rogers (2018); Rogers & Er (2019); Er & Rogers (2019), see also Clegg et al (1998). Note that in studies of interstellar scintillation the plasma column density is used instead of the volume density, see Rickett (1977).…”

“…For the wave effects in presence of Solar gravity and Solar corona, see Turyshev & Toth (2019a,b). For some recent studies see Schulze-Koops, Perlick & Schwarz (2017); Crisnejo & Gallo (2018); Crisnejo, Gallo & Rogers (2019); Er & Rogers (2018); Rogers & Er (2019); Er & Rogers (2019) ;Javed, Abbas & Övgün (2019); Sárený and Balek (2019); Crisnejo, Gallo & Jusufi (2019). Recent review of plasma effects in gravitational lensing was made by Bisnovatyi-Kogan & Tsupko (2017).…”