Sachs equations for light bundles in a cold plasma

Schulze-Koops, Karen; Perlick, Volker; Schwarz, Dominik J.

doi:10.1088/1361-6382/aa8d46

Cited by 17 publications

(21 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observational relevance of the influence of the plasma in the bending angle and in the associate quantities has been analyzed by different authors and for several astrophysical situations [47,48,71,88,89]. We would like to mention here that the plasma frequency f = ω e /2π usually takes values from few kHz to 100MHz [71]. Even when on the surface of the Earth we are limited by the ionosphere to observe only frequencies above 10MHz, there exists radioastronomy projects that consider the idea of putting in orbit 50 or more nanosatellites with low-frequency antennas with a frequency sensitivity in the range of 0.1-10MHz [45,46].…”

Section: Final Remarksmentioning

confidence: 99%

Weak lensing in a plasma medium and gravitational deflection of massive particles using the Gauss-Bonnet theorem. A unified treatment

2018

View full text Add to dashboard Cite

We apply the Gauss-Bonnet theorem to the study of light rays in a plasma medium in a static and spherically symmetric gravitational field and also to the study of timelike geodesics followed for test massive particles in a spacetime with the same symmetries. The possibility to using the theorem follows from a correspondence between timelike curves followed by light rays in a plasma medium and spatial geodesics in an associated Riemannian optical metric. A similar correspondence follows for massive particles. For some examples and applications, we compute the deflection angle in weak gravitational fields for different plasma density profiles and gravitational fields.PACS numbers:

show abstract

Section: Final Remarksmentioning

confidence: 99%

Weak lensing in a plasma medium and gravitational deflection of massive particles using the Gauss-Bonnet theorem. A unified treatment

2018

View full text Add to dashboard Cite

show abstract

“…Unlike light rays, both neutrinos and GWs in some theories beyond GR are timelike signals. Even for light rays in the real Universe, it was known that their propagation becomes timelike in a cold non-magnetized plasma [21]. The deflection and GL of these signals could have qualitatively different features comparing to null signals and therefore require separate treatment.…”

Section: Introductionmentioning

confidence: 99%

Time delay in the strong field limit for null and timelike signals and its simple interpretation

Liu

Jia

2021

Eur. Phys. J. C

View full text Add to dashboard Cite

Gravitational lensing can happen not only for null signals but also timelike signals such as neutrinos and massive gravitational waves in some theories beyond GR. In this work we study the time delay between different relativistic images formed by signals with arbitrary asymptotic velocity v in general static and spherically symmetric spacetimes. A perturbative method is used to calculate the total travel time in the strong field limit, which is found to be a quasi-power series of the small parameter $$a=1-b_c/b$$ a = 1 - b c / b where b is the impact parameter and $$b_c$$ b c is its critical value. The coefficients of the series are completely fixed by the behaviour of the metric functions near the particle sphere $$r_c$$ r c and only the first term of the series contains a weak logarithmic divergence. The time delay $$\Delta t_{n,m}$$ Δ t n , m to the leading non-trivial order was shown to equal the particle sphere circumference divided by the local signal velocity and multiplied by the winding number and the redshift factor. By assuming the Sgr A* supermassive black hole is a Hayward one, we were able to validate the quasi-series form of the total time, and reveal the effects of the spacetime parameter l, the signal velocity v and the source/detector coordinate difference $$\Delta \phi _{sd}$$ Δ ϕ sd on the time delay. It is found that as l increases from 0 to its critical value $$l_c$$ l c , both $$r_c$$ r c and $$\Delta t_{n,m}$$ Δ t n , m decrease. The variation of $$\Delta t_{n+1,n}$$ Δ t n + 1 , n for l from 0 to $$l_c$$ l c can be as large as $$7.2\times 10^1$$ 7.2 × 10 1 [s], whose measurement then can be used to constrain the value of l. While for ultra-relativistic neutrino or gravitational wave, the variation of $$\Delta t_{n,m}$$ Δ t n , m is too small to be resolved. The dependence of $$\Delta t_{n,-n}$$ Δ t n , - n on $$\Delta \phi _{sd}$$ Δ ϕ sd shows that to temporally resolve the two sequences of images from opposite sides of the lens, $$|\Delta \phi _{sd}-\pi |$$ | Δ ϕ sd - π | has to be larger than a certain value, or equivalently if $$|\Delta \phi _{sd}-\pi |$$ | Δ ϕ sd - π | is small, the time resolution of the observatories has to be good.

show abstract

“…Furthermore, following the discussions given by Synge in Ref. [33], such mathematical methods and similar ones, have made possible the determination and confinement of light propagation in the spacetimes of theoretical (non-)static black holes that are surrounded by plasmic or dark fluid media [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. Despite this, the analytical treatment of light ray trajectories in non-vacuum black hole surroundings is seemed to be overlooked.…”

Section: Introductionmentioning

confidence: 99%

Analytical study of light ray trajectories in Kerr spacetime in the presence of an inhomogeneous anisotropic plasma

Fathi,

Olivares,

Villanueva

2021

Preprint

View full text Add to dashboard Cite

We calculate the exact solutions to the equations of motion that govern the light ray trajectories as they travel in a Kerr black hole's exterior that is considered to be filled with an inhomogeneous and anisotropic plasmic medium. This is approached by characterizing the plasma through conceiving a radial and an angular structure function, which are let to be constant. The description of the motion is carried out by using the Hamilton-Jacobi method, that allows defining two effective potentials, characterizing the evolution of the polar coordinates. The (hyper-)elliptic integrals of motion are then solved analytically, and the evolution of coordinates is expressed in terms of the Mino time. This way, the three-dimensional demonstrations of the light ray trajectories are given respectively.

show abstract

Sachs equations for light bundles in a cold plasma

Cited by 17 publications

References 41 publications

Weak lensing in a plasma medium and gravitational deflection of massive particles using the Gauss-Bonnet theorem. A unified treatment

Weak lensing in a plasma medium and gravitational deflection of massive particles using the Gauss-Bonnet theorem. A unified treatment

Time delay in the strong field limit for null and timelike signals and its simple interpretation

Analytical study of light ray trajectories in Kerr spacetime in the presence of an inhomogeneous anisotropic plasma

Contact Info

Product

Resources

About