Diffraction of light by the gravitational field of the Sun and the solar corona

Turyshev, Slava G.; Toth, Viktor T.

doi:10.1103/physrevd.99.024044

Cited by 32 publications

(14 citation statements)

References 66 publications

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“…To develop reliable sensitivity estimates for imaging with the SGL, we need to consider the solar corona, which is the largest source of photometric noise [6]. For that, we model the solar corona as a 2-dimensional surface containing a collection of point emitters.…”

Section: Appendix A: Modeling the Solar Corona Signal In The Focal Planementioning

confidence: 99%

“…Recognizing its value for astronomy and astrophysics, recently we investigated the optical properties of the SGL and developed its wave-optical treatment [2,3,6]. With this knowledge, we studied photometric imaging with the SGL [7], estimating the total power that is incident on the aperture of an imaging telescope, thus measuring the amplitude of the incident signal.…”

Section: Introductionmentioning

confidence: 99%

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Imaging extended sources with the solar gravitational lens

Turyshev

Toth

2019

Phys. Rev. D

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We study the image formation process with the solar gravitational lens (SGL) in the case of an extended, resolved source. An imaging telescope, modeled as a convex lens, is positioned within the image cylinder formed by the light received from the source. In the strong interference region of the SGL, this light is greatly amplified, forming the Einstein ring around the Sun, representing a distorted image of the extended source. We study the intensity distribution within the Einstein ring observed in the focal plane of the convex lens. For any particular telescope position in the image plane, we model light received from the resolved source as a combination of two signals: light received from the directly imaged region of the source and light from the rest of the source. We also consider the case when the telescope points away from the extended source or, equivalently, it observes light from sources in sky positions that are some distance away from the extended source, but still in its proximity. At even larger distances from the optical axis, in the weak interference or geometric optics regions, our approach recovers known models related to microlensing, but now obtained via the wave-optical treatment. We then derive the power of the signal and related photon fluxes within the annulus that contains the Einstein ring of the extended source, as seen by the imaging telescope. We discuss the properties of the deconvolution process, especially its effects on noise in the recovered image. We compare anticipated signals from realistic exoplanetary targets against estimates of noise from the solar corona and estimate integration times needed for the recovery of high-quality images of faint sources. The results demonstrate that the SGL offers a unique, realistic capability to obtain resolved images of exoplanets in our galactic neighborhood. FIG. 1: The different optical regions of the SGL (adapted from [3]).SNRs, required integration times for a given observing scenario, to evaluate the quality of reconstructed images and, by doing so, to move the concept of imaging with the SGL from a domain of theoretical physics to the mainstream of astronomy and astrophysics.Our paper is organized as follows: Section II introduces the SGL and the solution for the EM field in the image plane in the strong interference region behind the Sun. Section III discusses the modeling of the intensity distribution observed in the focal plane behind the convex lens. We present the total signal received from the extended source as consisting of two parts: the signal from the directly imaged region of the source and the blur received from the rest of the source. Although our basic results are generic, to allow for the analytic evaluation of realistic observing scenarios, we model the source as a uniformly illuminated disk. This approach allows us to develop analytical expressions to estimate the total photon flux received by the telescope. In Section IV we study image formation in the geometric optics and weak interference regions, thus extending ...

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Section: Appendix A: Modeling the Solar Corona Signal In The Focal Planementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Imaging extended sources with the solar gravitational lens

Turyshev

Toth

2019

Phys. Rev. D

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“…With significant light amplification and impressive angular resolution of up to 2 × 10 11 and ∼ 0.5 nanoarcseconds, correspondingly (both for λ = 1 µm), the SGL may be used to image distant and faint sources. The impact of the solar corona on the optical properties of the SGL was examined in [4][5][6]. This study led to a conclusion that although for radio and microwave frequencies the optical properties of the SGL are severely affected by the plasma in the solar corona, for visible and infrared wavelengths, the contribution by the solar corona is negligible.…”

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confidence: 99%

Photometric imaging with the solar gravitational lens

Turyshev

Toth

2020

Phys. Rev. D

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We discuss the optical properties of the solar gravitational lens (SGL). We estimate the power of the EM field received by an imaging telescope. Studying the behavior of the EM field at the photometric detector, we develop expressions that describe the received power from a point source as well as from an extended resolved source. We model the source as a disk with uniform surface brightness and study the contribution of blur to a particular image pixel. To describe this process, we develop expressions describing the power received from the directly imaged region of the exoplanet, from the rest of the exoplanet and also the power for off-image pointing. We study the SGL's amplification and its angular resolution in the case of observing an extended source with a modest size telescope. The results can be applied to direct imaging of exoplanets using the SGL. I. INTRODUCTIONAccording to Einstein's general theory of relativity, the solar gravitational field changes the refractive properties of spacetime. This causes the trajectories of light to bend towards the Sun, resulting in the solar gravitational lens (SGL) [1][2][3]. With significant light amplification and impressive angular resolution of up to 2 × 10 11 and ∼ 0.5 nanoarcseconds, correspondingly (both for λ = 1 µm), the SGL may be used to image distant and faint sources. The impact of the solar corona on the optical properties of the SGL was examined in [4][5][6]. This study led to a conclusion that although for radio and microwave frequencies the optical properties of the SGL are severely affected by the plasma in the solar corona, for visible and infrared wavelengths, the contribution by the solar corona is negligible. The topic of practical use of the SGL for high-resolution imaging and spectroscopy of distant, faint objects recently also received significant attention, leading to the novel concept of a mission capable of reaching the focal region of the SGL and operating there for an extended period of time [7,8].Most of the prior work on the SGL dealt with studying the light from point sources at infinite distances from the lens. In [9], we initiated the discussion of using the SGL to image extended sources positioned at large but finite distances from the Sun, thus, moving closer to a possible practical use of this natural phenomenon. While considering the optical properties of the SGL in this case, it was realized that extended sources present an interesting challenge for imaging with the SGL. This challenge relates to a significant blurring of the images, which results in mixing light received from many widely separated areas of the surface of the source and distributing it across the entire image. Several methods of overcoming this challenge were developed. In particular, [10] demonstrated that the blurring can be removed by relying on modern deconvolution techniques developed to process microlensing images.In this paper we study the impact of blurring on photometric signals received when imaging extended resolved sources with a modest size telescop...

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“…Recent theoretical advances in the description of the wave-optical properties of the gravitational lens now allow for a precise description of its properties, including its point-spread function and the characteristics of the Einstein ring (Turyshev & Toth 2017. These properties can be used to describe the minimum and optimal physical size of a receiver in the focal plane, and its exact position in the heliocentric reference frame.…”

Section: Deep Space Nodesmentioning

confidence: 99%

Interstellar Communication Network. I. Overview and Assumptions

Hippke¹

2020

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It has recently been suggested in this journal by Benford (2019) that "Lurkers" in the form of interstellar exploration probes could be present in the solar system. Similarly, extraterrestrial intelligence could send long-lived probes to many other stellar systems, to report back science and surveillance. If probes and planets with technological species exist in more than a handful of systems in our galaxy, it is beneficial to use a coordinated communication scheme. Due to the inverse square law, data rates decrease strongly for direct connections over long distances. The network bandwidth could be increased by orders of magnitude if repeater stations (nodes) are used in an optimized fashion. This introduction to a series of papers makes the assumptions of the communication scheme explicit. Subsequent papers will discuss technical aspects such as transmitters, repeaters, wavelengths, and power levels. The overall purpose is to gain insight into the physical characteristics of an interstellar communication network, allowing us to describe the most likely sizes and locations of nodes and probes.

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Diffraction of light by the gravitational field of the Sun and the solar corona

Cited by 32 publications

References 66 publications

Imaging extended sources with the solar gravitational lens

Imaging extended sources with the solar gravitational lens

Photometric imaging with the solar gravitational lens

Interstellar Communication Network. I. Overview and Assumptions

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