Related papers: Using space-VLBI to probe gravity around Sgr A*
Gravitational-wave black-hole spectroscopy provides a unique opportunity to test the strong-field regime of gravity and the nature of the final object formed in the aftermath of a merger. Here we investigate the prospects for black-hole…
Whereas considerable effort has been afforded in understanding the properties of galaxies, a full physical picture, connecting their baryonic and dark-matter content, super-massive black holes, and (metric) theories of gravity, is still…
The Event Horizon Telescope (EHT) has recently delivered the first resolved images of M87*, the supermassive black hole in the center of the M87 galaxy. These images were produced using 230 GHz observations performed in 2017 April.…
The origin of supermassive black holes (SMBHs) residing in the centers of most galaxies remains a mystery. The Event Horizon Telescope (EHT) provided direct imaging of the SMBH Sgr A* at the Milky Way's center, indicating it likely spins…
The half opening angle of a Kerr black-hole shadow is always equal to (5+-0.2)GM/Dc^2, where M is the mass of the black hole and D is its distance from the Earth. Therefore, measuring the size of a shadow and verifying whether it is within…
The Event Horizon Telescope (EHT) imaging of the central objects in the M87 and Milky Way galaxies provide compelling evidence that these objects are consistent with (Kerr) black holes. In view of these observations and the future…
The images of supermassive black holes in M87 and our galaxy captured by the Event Horizon Telescope (EHT) might open up a new way for exploring black hole physics at the horizon scale. Theoretically, this could provide insights into…
Motivated by (i) more and more interest in strong gravitational lensing by supermassive black holes due to the achievement of EHT observations, (ii) the ongoing popular topic on the possibility of Lorentz symmetry being broken in…
The Event Horizon Telescope (EHT) collaboration has recently released the first image of a black hole (BH), opening a new window onto tests of general relativity in the strong field regime. In this paper, we derive constraints on the nature…
We show how Event Horizon Telescope (EHT) observations of the supermassive object at the center of M87 can constrain deviations from General Relativity (GR) in a relatively model-independent way. We focus on the class of theories whose…
The Event Horizon Telescope (EHT), a global submillimeter wavelength very long baseline interferometry array, unveiled event-horizon-scale images of the supermassive black hole M87* as an asymmetric bright emission ring with a diameter of $…
The Event Horizon Telescope (EHT) captured the first images of a black hole using Very Long Baseline Interferometry (VLBI). In the near future, extensions of the EHT such as the Black Hole Explorer (BHEX) will allow access to finer-scale…
Gas accretion of embedded stellar-mass black holes\,(sBHs) or stars in the accretion disk of active galactic nuclei\,(AGNs) will modify the mass distribution of these sBHs and stars, which will also affect the migration of the sBHs/stars.…
In general relativity, the angular radius of the shadow of a black hole is primarily determined by its mass-to-distance ratio and depends only weakly on its spin and inclination. If general relativity is violated, however, the shadow size…
The compact radio source Sagittarius~A$^*$ (Sgr~A$^*$)in the Galactic Center is the primary supermassive black hole candidate. General relativistic magnetohydrodynamical (GRMHD) simulations of the accretion flow around Sgr\,A$^*$ predict…
With its large collection area, broad-band energy coverage from optical/NIR (0.3 to 2.2 micron) to soft/hard X-ray (0.1-600 keV), all-sky monitoring capability, and on-board follow-up, the proposed Energetic X-ray Imaging Survey Telescope…
Observing the dynamics of compact astrophysical objects provides insights into their inner workings, thereby probing physics under extreme conditions. The immediate vicinity of an active supermassive black hole with its event horizon,…
We study gravitational lensing in the strong-field limit using the rotating quantum-corrected black hole (RQCBH) with an additional parameter $\alpha$ besides mass $M$ and spin parameter $a$. We discover a decrease in the deflection angle…
This is the second in a series of papers reporting on a large reverberation mapping (RM) campaign to measure black hole (BH) mass in high accretion rate active galactic nuclei (AGNs). The goal is to identify super-Eddington accreting…
The super massive black hole candidate, Sagittarius A*, exhibits variability from radio to X-ray wavelengths on time scales that correspond to < 10 Schwarzschild radii. We survey the potential of millimeter-wavelength VLBI to detect and…