Gravitational Lensing Effect Research Articles

Investigating gravitational lensing diffraction in the laboratory with structured light

We use spatial light modulation to investigate the diffractive effects of gravitational lensing in the laboratory. Using this new platform for laboratory astrophysics, we can overcome the coherence challenges that prevent the observation of diffraction in astronomical imaging. These studies will inform gravitational lensing of gravitational waves when imaging of gravitational waves becomes available. Our previous work involved studying lensing by a single mass, symmetric and elliptical. This work focuses on the patterns produced by a binary-mass system. We observed rich 2-dimensional interference patterns bounded by caustics. Comparison of experimental results with preliminary theoretical calculations is excellent.

Deep Photometry of Suspected Gravitational Lensing Events: Potential Detection of a Cosmic String

Cosmic strings (CS) are one-dimensional cosmological-size objects predicted in realistic models of the early Universe. Analysis of the cosmic microwave background (CMB) anisotropy data from the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck surveys revealed several CS candidates. One of the candidates, CSc-1, was found to be most reliable because of the statistically significant chains of gravitational lensing (GL) candidates in its field. We observed the brightest of the objects in the CSc-1 field, a galaxy pair SDSSJ110429.61+233150.3. The significant correlation between the spectra of the two components indicates the possible GL nature of the pair. Our simulations of observational data in the CSc-1 field shows that a large number of pairs can be explained by the complex geometry of the CS. Simulations of the SDSSJ110429 galaxy pair has shown that the observed angle between the components of the pair can be explained if the CS is strongly inclined and, possibly, bent in the image plane. In our preliminary data, we also detected the sign of the sharp isophotal edge in one image, which along with CMB and spectral data strongly suggests the possibility of a CS detection.

Weak gravitational lensing and shadow of a GUP-modified Schwarzschild black hole in the presence of plasma

In this work, we have studied weak gravitational lensing effect around black hole and determine shadow radius in GUP-corrected-Schwarzschild spacetime (S-GUP) in presence of plasma environment. We started with orbits of photons around black hole in S-GUP. In addition, we have studied shadow and gravitational weak lensing around such black hole. By using observational data of EHT project for the M87* and Sgr A*, we have got constrains parameter ϵ in S-GUP gravity. Further to make a connection with observations, we investigate magnification and position of images formed as a result of lensing, and finally weak deflection angle and magnification for sources near M87* and Sgr A*.

Gravitational lensing effects of black hole with conformally coupled scalar hair

In this paper, we investigate the gravitational lensing effects in the weak and strong field limits of a static black hole with conformally coupled scalar field. In the weak field limit, with the use of Gauss–Bonnet theorem we calculate the deflection angle of the light. It is found that comparing to Schwarzschild and Reissner–Nordstro¨\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ddot{\ ext {o}}$$\\end{document}m (RN) black holes in general relativity, the weak deflection angle can be enhanced/suppressed by the scalar hair. In the strong field limit, we first compute the light deflection angle via calculating the lensing coefficients, all of which increase as the values of electric and scalar charges increase. Then we evaluate the lensing observables in strong field regime by supposing the hairy black hole as the candidate of M87* and SgrA* supermassive black holes, respectively. We find that the scalar hair has significant influences on various observables. In particular, the lensing observables of the charged black hole with positive scalar hair and RN black hole have degeneracy, which will be broken by the case with negative scalar hair. Our theoretical findings imply that it is feasible to employ the gravitational lensing effects as a probe of Einstein–Maxwell theory with negative scalar field differentiating from general relativity, once the future astrophysical observation is precise enough.

Solving the inverse cosmological calibration problem of gamma-ray bursts

ABSTRACT We have received a new physical characteristics fitting based on actual observational data from the Swift mission’s long-duration gamma-ray bursts (LGRBs). We considered such characteristics as the Amati parameters for linear correlation (Eiso–Ep,i) and the k-correction for gravitational lensing and Malmquist bias (GLMB) effect. We used the Pantheon SN Ia catalogue and the standard Lambda cold dark matter model with a fixed Hubble constant of H0 = 70 km s−1 Mpc−1 as the baseline for the Hubble function μ(z). In our paper, we formulated the inverse cosmological calibration problem (ICCP) in the non-parametric statistics framework. The ICCP involves fitting non-observable physical characteristics while assuming a fixed cosmological model. To solve this problem, we developed a new method that is resistant to non-Gaussian processes. This method is based on error propagation through the Monte Carlo method and the Theil–Sen method for linear regression estimate. We have demonstrated the stability and robustness of this assessment method. The parameter estimates are as follows: $a=0.92^{+0.12}_{-0.12}$, $b=50.32^{+0.33}_{-0.32}$ without considering the GLMB effect, and $a=0.63^{+0.13}_{-0.14}$, $b=50.12^{+0.33}_{-0.31}$, and $k=1.98^{+0.25}_{-0.24}$ with the effect included. The proposed method can be applied to any other calibration sample of known standard candles, a calibrated sample of LGRBs, and the Hubble function μ(z). In the future, the ICCP idea can be used as an alternative cosmological test for estimating cosmological parameters, including the GLMB effect, or even for the selection of models, providing new information about the Universe. This can be done by analysing the residual values of observational data within the Bayesian statistics paradigm.

Improving constraints on models addressing the Hubble tension with CMB delensing

The Hubble Tension is a well-known issue in modern cosmology that refers to the apparent disagreement in inferences of the Hubble constant H 0 as found through low-redshift observations and those derived from the ΛCDM model utilizing early universe observations. Several extensions to ΛCDM have been proposed to address the Hubble Tension that involve new ingredients or dynamics in the early universe. Reversing the effects of gravitational lensing on cosmic microwave background (CMB) maps produces sharper acoustic peaks in power spectra and allows for tighter constraints on cosmological parameters. We investigate the efficacy of CMB delensing for improving the constraints on parameters used in extensions of the ΛCDM model that are aimed at resolving the Hubble Tension (such as varying fundamental constants, contributions from early dark energy, and self-interacting dark radiation). We use Fisher forecasting to predict the expected constraints with and without this delensing procedure. We demonstrate that CMB delensing improves constraints on H 0 by ∼ 20% for viable models and significantly improves constraints on parameters across the board in the low-noise regime.

Gravitational lensing effect in the Universe with a Finsler background

The gravitational deflection of light is a common effect for the massive objects in galactic astronomy. Recently, several universal models with Finsler background were introduced to solve the abnormal phenomena. In this manuscript, we consider the deflection of gravitational lens in a general Finsler space. Firstly, with the assistance of the Landsberg angle, we introduce four definitions of the deflection angle, which are not equal mutually in general case. Secondly, we introduce an important concept called asymptotically symmetric Minkowskian flat (ASMF) manifold, on which we define the global normal deflection angle (GNDA) as well as the global tangent deflection angle (GTDA). Lastly, we present an integral expression of the GNDA on an ASMF manifold. This result suggests to us that the non-Riemannian Finsler quantities may contain the information of dark matter.

The Mass–Metallicity Relation of Dwarf Galaxies at Cosmic Noon from JWST Observations

We present a study of the mass–metallicity relation (MZR) of 51 dwarf galaxies (M ⋆ ≈ 106.5–109.5 M ⊙) at z = 2–3 from the A2744 and SMACS J0723-3732 galaxy cluster fields. These dwarf galaxies are identified and confirmed by deep JWST/NIRISS imaging and slitless grism spectroscopic observations. By taking advantage of the superior performance of JWST and the gravitational lensing effect, we extend the previous MZR relation at z = 2–3 to a much lower-mass regime down by ≈2.5 orders of magnitude as compared with previous studies. We find that the MZR has a shallower slope at the low-mass end (M ⋆ < 109 M ⊙), with a slope turnover point of ≈109 M ⊙. This implies that the dominating feedback processes in dwarf galaxies may be different from that in massive galaxies. From z = 3, to z = 2, the metallicity of the dwarf galaxies is enhanced by ≈0.09 dex for a given stellar mass, consistent with the mild evolution found in galaxies with higher mass. Furthermore, we confirm the existence of a fundamental metallicity relation (FMR) between the gas-phase metallicity, stellar mass, and star formation rate in dwarf galaxies at z = 2–3. Our derived FMR, which has no significant redshift evolution, can be used as a benchmark to understand the origin of the anticorrelation between the star formation rate and metallicity of dwarf galaxies in the high-z Universe.

Photon motion and weak gravitational lensing in black-bounce spacetime* *Supported by Grant F-FA-2021-510 of the Uzbekistan Ministry for Innovative Development

The effect of spacetime curvature on photon motion may offer an opportunity to propose new tests on gravity theories. In this study, we investigate and focus on the massless (photon) particle motion around black-bounce gravity. We analyze the horizon structure around a gravitational compact object described by black-bounce spacetime. The photon motion and the effect of gravitational weak lensing in vacuum and plasma are discussed, and the shadow radius of the compact object is also studied in black-bounce spacetime. Additionally, the magnification of the image is studied using the deflection angle of light rays.

Effects of gravitational lensing by Kaluza-Klein black holes on neutrino oscillations

We study gravitational lensing of neutrinos in a Kaluza-Klein black hole spacetime and compare the oscillation probabilities of neutrinos with the case of lensing by black holes in General Relativity. We show that measuring neutrino oscillations in curved spacetimes may allow us to distinguish the two kinds of black holes even in the weak-field limit, as opposed to what happens for the weak lensing of photons. This promises to become an useful tool for future measurements of the properties of black hole candidates and possibly help to constrain the validity of alternative theories of gravity.

Einstein beams and the diffractive aspect of gravitationally-lensed light

The study of light lensed by cosmic matter has yielded much information about astrophysical questions. Observations are explained using geometrical optics following a ray-based description of light. After deflection the lensed light interferes, but observing this diffractive aspect of gravitational lensing has not been possible due to coherency challenges caused by the finite size of the sources or lack of near-perfect alignment. In this article, we report on the observation of these wave effects of gravitational lensing by recreating the lensing conditions in the laboratory via electro-optic deflection of coherent laser light. The lensed light produces a beam containing regularities, caustics, and chromatic modulations of intensity that depend on the symmetry and structure of the lensing object. We were also able to observe previous and new geometric-optical lensing situations that can be compared to astrophysical observations. This platform could be a useful tool for testing numerical/analytical simulations, and for performing analog simulations of lensing situations when they are difficult to obtain otherwise. We found that laboratory lensed beams constitute a new class of beams, with long-range, low expansion, and self-healing properties, opening new possibilities for non-astrophysical applications.

Testing new massive conformal gravity with the light deflection by black hole

We study the weak gravitational lensing effect of Non-Bocharova-Bronnikov-Melnikov-Bekenstein (BBMB) black hole in new massive conformal gravity. We analyze the deflection angle of light caused by new massive conformal gravity by using the Gauss-Bonnet theorem. As a consequence, we obtain the Gaussian optical curvature and calculate the deflection angle of the new massive conformal gravity for spherically balanced space-time with the Gauss-Bonnet theorem. The resultant deflection angle of light in the weak field limits showing that the bending of light is a global and topological phenomenon. Furthermore, we identify the deflection angle of light in the framework of the plasma medium, we also demonstrate the effect of a plasma medium on the deflection of light by non BBMB. In addition, the behavior of the deflection angle by new massive conformal gravity is explicitly shown in the influence of plasma medium and for the non plasma medium.

Lensing of gravitational waves from tidal disruption events

ABSTRACT In this work, we investigate the effect of gravitational lensing on the gravitational wave (GW) signals of a population of tidal disruption events (TDEs). We estimate the number of lensed-magnified signals that we expect to detect with future space-based GW observatories, in particular LISA and DECIGO. We model the lens distribution using an hybrid approach that combines semi-analytic methods with numerical results from ray tracing simulations. We divide the TDE population in two classes, nuclear TDEs (main sequence stars tidally disrupted by massive black holes in the cores of galaxies) and globular TDEs (white dwarfs tidally disrupted by intermediate mass black holes in globular clusters). We find that, even considering the effect of lensing, LISA will not be able to observe any TDEs, while DECIGO could detect ∼16 strongly lensed (μ &amp;gt; 2) globular TDEs and ∼135 strongly lensed nuclear TDEs, over an observational period of 10 yr. Our results reveal the role that lensing will play in future deci-Hertz GW observatories, indicating exciting multimessenger opportunities with TDEs but at same time signalling the need to develop adequate data analysis techniques to correctly reconstruct the astrophysical properties of the source.

Detecting and Characterizing Young Quasars. III. The Impact of Gravitational Lensing Magnification

We test the impact of gravitational lensing on the lifetime estimates of seven high-redshift quasars at redshift z ≳ 6. The targeted quasars are identified by their small observed proximity zone sizes, which indicate extremely short quasar lifetimes (t Q ≲ 105yr). However, these estimates of quasar lifetimes rely on the assumption that the observed luminosities of the quasars are intrinsic and not magnified by gravitational lensing, which would bias the lifetime estimates toward younger ages. In order to test the possible effects of gravitational lensing, we obtain high-resolution images of the seven quasars with the Hubble Space Telescope and look for signs of strong lensing. We do not find any evidence of strong lensing, i.e., all quasars are well described by point sources, and no foreground lensing galaxy is detected. We estimate that the strong-lensing probabilities for these quasars are extremely small (∼1.4 × 10−5) and show that weak lensing changes the estimated quasar lifetimes by only ≲0.2 dex. We thus confirm that the short lifetimes of these quasars are intrinsic. The existence of young quasars indicates a high obscured fraction, radiatively inefficient accretion, and/or flickering lightcurves for high-redshift quasars. We further discuss the impact of lensing magnification on measurements of black hole masses and Eddington ratios of quasars.

Shadow revisiting and weak gravitational lensing with Chern-Simons modification

Dynamical Chern-Simons (dCS) gravity has been attracting plenty of attentions due to the fact that it is a parity-violating modified theory of gravity that corresponds to a well-posed effective field theory in weak coupling approximation. In particular, a rotating black hole in dCS gravity is in contrast to the general relativistic counterparts. In this paper, we revisit the shadow of analytical rotating black hole spacetime in dCS modified gravity, based on which we study the shadow observables, discuss the constraint on the model parameters from the Event Horizon Telescope (EHT) observations, and analyze the real part of quasi-normal modes (QNMs) in the eikonal limit. In addition, we explore the deflection angle in weak gravitational field limit with the use of Gauss-Bonnet theorem. We find that the shadow related physics and the weak gravitational lensing effect are significantly influenced by the CS coupling, which could provide theoretical predictions for a future test of the dCS theory with EHT observations.

Characteristic Features of Gravitational Wave Lensing as Probe of Lens Mass Model

AbstractTo recognize gravitational wave lensing events and being able to differentiate between similar lens models will be of crucial importance once one will be observing several lensing events of gravitational waves per year. In this work, the lensing of gravitational waves is studied in the context of LISA sources and wave‐optics regime. While different papers before the studied microlensing effects enhanced by simultaneous strong lensing, the focus is on frequency (time) dependent phase effects produced by one lens that will be visible with only one lensed signal. It is shows how, in the interference regime (i.e., when interference patterns are present in the lensed image), one is able to i) distinguish a lensed waveform from an unlensed one, and ii) differentiate between different lens models. In pure wave‐optics, on the other hand, the feasibility of the study depends on the signal‐to‐noise ratio of the signal and/or the amplitude of the lensing effect. To achieve these goals, the phase of the amplification factor of the different lens models and its effect on the unlensed waveform is studied, and the signal‐to‐noise calculation to provide some quantitative examples is exploited.

Gravitational lensing by a charged spherically symmetric black hole immersed in thin dark matter

We investigate the gravitational lensing effect around a spherically symmetric black hole, whose metric is obtained from the Einstein field equation with electric charge and perfect-fluid dark matter contributing to its energy-momentum tensor. We do the calculation analytically in the weak field limit and we assume that both the charge and the dark matter are much less abundant (only give rise to the next-leading-order contribution) in comparison to the black hole mass. In particular, we derive the light deflection angle and the size of the Einstein ring, where approximations up to the next-leading order are done with extra care, especially for the logarithmic term from perfect-fluid dark matter. We expect our results will be useful in the future to relate the theoretical model of perfect fluid dark matter with observations of celestial bodies immersed in thin dark matter.

Weak Gravitational Lensing around Bardeen Black Hole with a String Cloud in the Presence of Plasma

The effect of spacetime curvature on optical properties may provide an opportunity to suggest new tests for gravity theories. In this paper, we investigated gravitational weak lensing around a Bardeen black hole with the string clouds parameter. First, we examined the horizon structure in the presence of string clouds around the gravitational compact object defined by Bardeen spacetime. The effect of gravitational weak lensing in a plasma medium is also discussed. According to the findings, the influence of the string cloud parameter on the circular orbits of a light ray around the black hole is greater than that in the Schwarzschild case, while the influence of the charge is reversed. The deflection angle of light rays in weak lensing is also used to study how much the image is magnified.

СЛАБОЕ ГРАВИТАЦИОННОЕ ЛИНЗИРОВАНИЕ ЧЕРНЫМИ ДЫРАМИ С ЗАРЯДОМ

The deflection of light due to gravity was predicted by general relativity and first confirmed by observations in 1919. In the following decades, various aspects of the gravitational lensing effect were theoretically explored, including the possibility of obtaining multiple or annular images of background sources, the use of lensing as a gravitational telescope on very faint and distant objects, and the possibility of determining the Hubble constant using lensing. Gravitational lensing is the deflection of light by gravity caused by the action of compact astrophysical objects. Various objects, such as a galaxy, stars, black holes, wormholes, and others, can act as a gravitational lens. In our study, as a gravitational lens, we chose black holes described by the Gibbons-Maeda-GarfinkleHorowitz-Strominger solutions in the string frame. The two solutions in the string frame are magnetically and electrically charged black holes with an event horizon. The work will investigate the effect of electric and magnetic charges on the angle of deflection of light.

Geometric Outlines of the Gravitational Lensing and Its Astronomic Applications

Gravitational lensing is a topic of great application value in the field of astronomy. The properties and research methods of gravitational lensing are closely related to the geometric and relativistic characteristics of the background universe. This review focuses on the theoretical research and application of strong lenses and weak lenses. We first introduce the basic principles of gravitational lensing, focusing on the geometric basis of geometric lensing, the representation of deflection angles, and the curvature relationship in different geometric spaces. In addition, we summarize the wide range of applications of gravitational lensing, including the application of strong gravitational lensing in Schwarzschild black holes, time delay, the cosmic shearing based on weak lensing, the applications in signal extraction, dark matter, and dark energy. In astronomy, through the use of advanced astronomical instruments and computers, analyzing gravitational lensing effects to understand the structure of galaxies in the universe is an important topic at present. It is foreseeable that gravitational lensing will continue to play an important role in the study of cosmology and will enrich our understanding of the universe.