Related papers: Coordinated mm/sub-mm observations of Sagittarius …

Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, undergoes large-amplitude near-infrared (NIR) flares that can coincide with the continuous rotation of the NIR emission region. One promising explanation…

We have performed monitoring observations of the 3-mm flux density toward the Galactic Center compact radio source Sgr A* with the Australia Telescope Compact Array since 2005 October. Careful calibrations of both elevation-dependent and…

Sagittarius A*, the supermassive compact object at the center of the Galaxy, exhibits outbursts in the near infrared and X-ray domains. These flares are likely due to energetic events very close to the central object, on a scale of a few…

Observations of Sagittarius A* (Sgr A*) in near-infrared (NIR) show irregular flaring activity. Flares coincide with astrometric rotation of brightness centroid and with looping patterns in fractional linear polarization. These signatures…

The relatively rapid spatial and temporal variability of the X-ray radiation from some molecular clouds near the Galactic center shows that this emission component is due to the reflection of X-rays generated by a source that was luminous…

This paper presents the Suzaku results obtained for the Sagittarius (Sgr) C region using the concept of X-ray reflection nebulae (XRNe) as the echo of past flares from the super massive black hole, Sgr A*. The Sgr C complex is composed of…

The image of the emission surrounding the black hole in the center of the Milky Way is predicted to exhibit the imprint of general relativistic (GR) effects, including the existence of a shadow feature and a photon ring of diameter ~50…

At radio wavelengths, images of the compact radio source Sagittarius A* (Sgr A*) in the Galactic Center are scatter broadened with a lambda^2 dependence due to an intervening ionized medium. We present VLBI observations of Sgr A* at 86 GHz…

This review outlines the observations that now provide an overwhelming scientific case that the center of our Milky Way Galaxy harbors a supermassive black hole. Observations at infrared wavelength trace stars that orbit about a common…

The dark compact object at the centre of the Milky Way is well established to be a supermassive black hole with mass $M_{\bullet} \sim 4.3 \cdot 10^6 \, M_{\odot}$, but the nature of its environment is still under debate. In this work, we…

We present a simple argument that the missing x-ray flux from the Galactic Center source Sgr~A* ist not evidence {\it against} -- as claimed by Goldwurm et al. 1994 -- but rather indirect evidence {\it for} the presence of a supermassive…

Monitoring of Sagittarius A* from X-ray to radio wavelengths has revealed structured variability --- including X-ray flares --- but it is challenging to establish correlations between them. Most studies have focused on variability in the…

Recently, Vagnozzi and Visinelli's work [Phys. Rev. D 100, 024020 (2020)] reveals that M87*'s shadow establishes an upper limit of $l \lesssim 170$ AU, where $l$ is the AdS$_5$ curvature radius and 1 AU is one astronomical unit. The Event…

Understanding the variability of Sagittarius A* (Sgr A*) requires coordinated, multi-wavelength observations that span the electromagnetic spectrum. In this work, we focus on data from four key observatories: Chandra in the X-ray (2-8 keV),…

We present new SHARP/NTT stellar proper motion and accelaration data covering an interval from 1992 to 2000: 1) We combine the high precision but shorter time scale NIRC/Keck data with the lower precision but longer time scale SHARP/NTT…

We present the results of a 3.3-year project to monitor the flux density of Sagittarius A* at 2.0, 1.3, and 0.7 cm with the VLA. The fully calibrated light curves for Sgr A* at all three wavelengths are presented. Typical errors in the flux…

In this paper we simultaneously fit the orbits and line-of-sight velocities of the ionized gas around the supermassive black hole, Sagittarius A$^{\ast}$ (Sgr A$^{\ast}$), at the center of the Milky Way. The data we use are taken with the…

Observations of the Galactic Center supermassive black hole Sagittarius A* (Sgr A*) with very long baseline interferometry (VLBI) are affected by interstellar scattering along our line of sight. At long radio observing wavelengths…

Assuming that the compact source at the Galactic center, Sagittarius A*, is a massive boson star, we fit the near-infrared flare astrometry data. We consider 12 discrete boson star configurations and model the flare as a hotspot on a…

Millimeter wave Very Long Baseline Interferometry (mm-VLBI) provides access to the emission region surrounding Sagittarius A*, the supermassive black hole at the center of the Milky Way, on sub-horizon scales. Recently, a closure phase of…