We investigate retrolensing by two photon spheres in a novel black-bounce spacetime suggested by Lobo et al. which can correspond to a Schwarzschild black hole, a regular black hole, and a traversable wormhole including an Ellis-Bronnikov wormhole. In a case, the wormhole has a throat which acts as a photon sphere and it has another photon sphere outside of the throat. With the sun as a light source, an observer, and the wormhole are lined up in this order, sunlight reflected slightly outside of the throat and barely outside and inside of the outer photon sphere can reach the observer. We show that the light rays reflected by the outer photon sphere are dominant in retrolensing light curves in the case.
We investigate retrolensing of sunlights reflected by a photon sphere and by a potential barrier near an antiphoton sphere around a Reissner-Nordström naked singularity. We apply the deflection angles of light rays in strong deflection limits to the retrolensing. We show that the retrolensing by the photon sphere around the Reissner-Nordström naked singularity can be brighter than the one around a Reissner-Nordström black hole because of the existence of the rays which reflected by the potential barrier.
Compact objects with a light sphere such as black holes and wormholes can reflect light rays like a mirror. This gravitational lensing phenomenon is called retrolensing and it is an interesting tool to survey dark and compact objects with a light sphere near the solar system. In this paper, we calculate the deflection angle analytically in the strong deflection limit in the Reissner-Nordstrom spacetime without Taylor expanding it in the power of the electric charge. Using the obtained deflection angle in the strong deflection limit, we investigate the retrolensing light curves and the separati…
The deflection angle of a light ray can be arbitrarily large near a light sphere. The time-symmetrical shape of light curves of a pair of light rays reflected by a light sphere of a lens object does not depend on the details of the lens object. We consider retrolensing light curves of sunlight with deflection angles $π$ and $3π$ by an Ellis wormhole, which is the simplest Morris-Thorne wormhole. If an Ellis wormhole with a throat parameter $a=10^{11}$ km is $100$ pc away from an observer and if the Ellis wormhole, the observer, and the sun are aligned perfectly in this order, the apparent magn…
We investigate gravitational lensing by a primary photon sphere which is a sphere filled with unstable circular light orbits, and by a secondary photon sphere on a wormhole throat in a black-bounce spacetime which is suggested in [F. S. N. Lobo, M. E. Rodrigues, M. V. d. S. Silva, A. Simpson, and M. Visser, Phys. Rev. D 103, 084052 (2021)] in strong deflection limits. There is an antiphoton sphere between the primary photon sphere and the secondary photon sphere. If a light source and an observer are on the same side of the wormhole throat, in addition to an infinite number of images slightly …
Gravitational lensing is a good probe into the topological structure of dark gravitating celestial objects. In this paper, we investigate the light curve of a light ray that passes through the throat of an Ellis wormhole, the simplest example of traversable wormholes. The method developed here is also applicable to other traversable wormholes. To study whether the light curve of a light ray that passes through a wormhole throat is distinguishable from that which does not, we also calculate light curves without the passage of a throat for an Ellis wormhole, a Schwarzschild black hole, and an ul…
A Simpson-Visser spacetime has two nonnegative parameters $a$ and $m$ and its metric is correspond with (i) a Schwarzschild metric for $a=0$ and $m\neq0$, (ii) a regular black hole metric for $a<2m$, (iii) a one-way traversable wormhole metric for $a=2m$, (vi) a two-way traversable wormhole metric for $a>2m$, and (v) an Ellis-Bronnikov wormhole metric for $a\neq0$ and $m=0$. The spacetime is one of the most useful spacetimes for the purpose of comprehensively understanding gravitational lensing of light rays reflected by a photon sphere of black holes and wormholes. We have investigated gravit…
Echoes and quasinormal modes of asymmetric black bounces
Universidade Federal do Ceará (UFC)（塞阿拉联邦大学）；Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València（瓦伦西亚大学/西班牙国家研究委员会粒子物理研究所）；Programa de Pós-graduação em Física, Universidade Federal do Maranhão（马拉尼昂联邦大学）
By replacing the scalar $ϕ$ with $iϕ$ in the solution constructed in Ref\cite{Huang:2019lsl}, we obtain electrically-charged wormhole and black hole solutions in the Einstein-Maxwell-scalar theory, in which the scalar is a phantom field coupled to the Maxwell field non-minimally. Our solutions are simpler than the previously-known charged wormholes in the Einstein-Maxwell-dilaton theory in that both the scalar and the radius of the foliating sphere of our solutions are independent of electric charge. The wormhole solution has two asymptotically flat regions and reduces to Ellis wormhole when t…
Shadows and gravitational perturbations of black bounces
Universidade Federal do Ceará (UFC)（塞阿拉联邦大学）；Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València（瓦伦西亚大学-CSIC粒子物理研究所）；Faculdade de Física, Campus Salinópolis, Universidade Federal do Pará（帕拉州联邦大学萨利诺波利斯校区物理学院）
From massless wormholes to massive black bounces: Shadows and multiple light rings
Universidade Federal do Ceará（塞阿拉联邦大学）；Center of Gravitation and Fundamental Metrology, Rostest（引力与基本计量中心，罗斯特斯特）；Peoples’ Friendship University of Russia（俄罗斯人民友谊大学）；National Research Nuclear University ”MEPhI”（国立核研究大学莫斯科工程物理学院）
Corrected thermodynamics and radiation predictions of modified black bounce compact objects
Kimyo International University in Tashkent（塔什干化学国际大学）；Tashkent State Technical University（塔什干国立技术大学）；School of Physics, Harbin Institute of Technology（哈尔滨工业大学物理学院）；University of Tashkent for Applied Sciences（塔什干应用科学大学）；Farabi University（法拉比大学）；Fesenkov Astrophysical Institute（费森柯夫天体物理研究所）；Center for Theoretical Physics, Khazar University（哈扎尔大学理论物理中心）；Chitkara University Institute of Engineering and Technology, Chitkara University（奇特拉卡大学工程与技术学院，奇特拉卡大学）；National University of Uzbekistan（乌兹别克斯坦国立大学）；Department of Physics, Jizzakh State Pedagogical University（吉扎克国立师范学院物理系）；Tashkent State Medical University（塔什干国立医科大学）
Optical appearance of regularized compact objects without an exterior photon sphere
PDPIAS, Charotar University of Science and Technology（查洛塔尔科学技术大学）；International Centre for Space and Cosmology, School of Arts and Sciences, Ahmedabad University（艾哈迈达巴德大学艺术与科学学院国际空间与宇宙学中心）
In this paper we study the dynamics of $ n-1$ dimensional domain wall universe embedded in a $n$ dimensional charged dilaton black hole bulk with the non-asymptotically flat and non-asymptotically (A)dS characters. We find that domain wall can always cross horizon, for which the dilaton coupling constant $a$ and the ratio of pressure to density $w$ play the role of controlling parameters. Then the consequent domain wall motion outside the black hole generally falls into four situations: all time accelerating expansion, slow expansion with a constant speed, expansion followed by collapsing into…
