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In the framework of the unimodular metagravity, with the scalar graviton/graviscalar dark matter, a regular anomalous one-parameter solution to the static spherically symmetric metagravity equations in empty space is found. The solution…

General Relativity and Quantum Cosmology · Physics 2010-10-19 Yu. F. Pirogov

We study strong gravitational lensing due to a Schwarzschild black hole. Apart from the primary and the secondary images we find a sequence of images on both sides of the optic axis; we call them {\em relativistic images}. These images are…

Astrophysics · Physics 2009-10-31 K. S. Virbhadra , George F. R. Ellis

Black holes are the most compact objects in the Universe. According to general relativity, black holes have a horizon that hides a singularity where Einstein's theory breaks down. Recently, gravitational waves opened the possibility to…

General Relativity and Quantum Cosmology · Physics 2022-12-01 Elisa Maggio

Direct detection of gravitational waves from several compact binary coalescences has ushered in a new era of astronomy. It has opened up the possibility of detecting ultralight bosons, predicted by extensions of the Standard Model, from…

General Relativity and Quantum Cosmology · Physics 2021-11-19 Shrobana Ghosh

Optical appearance of a compact binary star in the field of a supermassive black hole is modeled in a strong field regime. Expressions for the redshift, magnification coefficient and pulsar extinction time are derived. By using the vierbein…

General Relativity and Quantum Cosmology · Physics 2017-02-28 Alexander Gorbatsievich , Stanislav Komarov , Alexander Tarasenko

We propose a new model of a {\it gravastar} admitting conformal motion. While retaining the framework of the Mazur-Mottola model, the gravastar is assumed to be internally charged, with an exterior defined by a Reissner-Nordstr{\"o}m rather…

General Relativity and Quantum Cosmology · Physics 2011-06-06 A A Usmani , Farook Rahaman , Saibal Ray , K K Nandi , Peter K. F. Kuhfittig , Sk. A Rakib , Z Hasan

This paper studies the influence of charge on a compact stellar structure also regarded as vacuum condensate star in the background of $f(\mathfrak{R},\mathcal{T}^{2})$ gravity. This object is considered the alternate of black hole whose…

General Relativity and Quantum Cosmology · Physics 2022-08-10 M. Sharif , Saba Naz

Exotic compact objects with physical surfaces a Planckian distance away from where the horizon would have been are inspired in quantum gravity. Most of these objects are defined by a classical spacetime metric, such as boson stars,…

General Relativity and Quantum Cosmology · Physics 2020-02-19 Andrea Addazi , Antonino Marciano , Nicolas Yunes

The characteristic and distinctive features of the visibility amplitude of interferometric observations for compact objects like stars in the immediate vicinity of the central black hole in our Galaxy are considered. These features are…

Astrophysics of Galaxies · Physics 2016-07-20 Alexander Shatskiy , Yu. Yu. Kovalev , I. D. Novikov

A nearly black, gravitationally intense star of semi-transparent, spherical, massive shell containing a few pointlike light sources inside would be perceived not like a three-dimensional ball for a localized observer outside the shell in…

General Relativity and Quantum Cosmology · Physics 2020-07-08 Shih-Yuin Lin

We propose the novel method of ``gravitational imaging'' to detect and quantify luminous and dark-matter substructure in gravitational-lens galaxies. The method utilizes highly-magnified Einstein rings and arcs as sensitive probes of small…

Astrophysics · Physics 2015-06-24 L. V. E. Koopmans

Pushed by a number of advances, electromagnetic observatories have now reached the horizon scale of supermassive black holes. The existence and properties of horizons in our universe is one of the outstanding fundamental issues that can now…

General Relativity and Quantum Cosmology · Physics 2022-08-16 João Luís Rosa , Paulo Garcia , Frédéric H. Vincent , Vitor Cardoso

Over the next decade, third-generation interferometers and the space-based LISA mission will observe binaries in galactic centers involving supermassive black holes with millions of solar masses. More precise measurements of more extreme…

General Relativity and Quantum Cosmology · Physics 2023-08-09 Francisco Duque

This work is devoted to study the analytical and regular solutions of a particular self-gravitating object (i.e., gravastar) in a particular theory of gravity. We derive the corresponding field equations in the presence of effective energy…

General Relativity and Quantum Cosmology · Physics 2021-08-30 Z. Yousaf , M. Z. Bhatti , H. Asad

In the presence of an ultralight bosonic field, spinning black holes are unstable to superradiance. The rotational energy of the black hole is converted into a non-axisymmetric, oscillating boson cloud which dissipates through the emission…

General Relativity and Quantum Cosmology · Physics 2020-01-09 Nils Siemonsen , William E. East

Gravitational wave astronomy is an emerging observational discipline that expands the astrophysical messengers astronomers can use to probe cosmic phenomena. The gravitational waveform from a source encodes the astrophysical properties and…

General Relativity and Quantum Cosmology · Physics 2023-03-20 Steven Pakiela , Brett Bolen , Ben Holder , Monica Rizzo , Shane L. Larson

The physical properties of a (3+1)-D gravastar in the context of massive gravity are discussed in this work. In present investigation, the field equations have been solved for a static, uncharged sphere in order to achieve the gravastar…

General Relativity and Quantum Cosmology · Physics 2024-04-10 Piyali Bhar

This study explores the effect of charge on a special astronomical object known as a gravastar, which is viewed as an alternative to a black hole. Based on the conjecture put out by Mazur and Mottola in general relativity, the study…

General Relativity and Quantum Cosmology · Physics 2024-05-01 Faisal Javed , Arfa Waseem , G. Mustafa , Fairouz Tchier , Farruh Atamurotov , Bobomurat Ahmedov , Ahmadjon Abdujabbarov

Gravitational vacuum condensate stars, also known as gravastars, have been proposed as an alternative to black holes. Their interior contains a perfect fluid with an equation of state akin to that of a cosmological constant. For this…

General Relativity and Quantum Cosmology · Physics 2023-08-16 P. P. Avelino

In this work are reviewed several aspects of gravitational lensing produced by astrophysical bodies that strongly curve the spacetime in their vicinity. When an object with a photon sphere (e.g. a black hole) is interposed between a source…

General Relativity and Quantum Cosmology · Physics 2014-09-15 Ernesto F. Eiroa