Related papers: Limits on the Position Wander of Sgr A*

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…

The massive black hole at the Galactic Centre is known to be variable in radio, millimeter, near-IR and X-rays. We investigate the physical processes responsible for the variable observed emissions from the compact radio source Sgr A*. We…

We report the detection of radio QPOs with structure changes using the Very Long Baseline Array (VLBA) at 43 GHz. We found conspicuous patterned changes of the structure with P = 16.8 +- 1.4, 22.2 +- 1.4, 31.2 +- 1.5, 56.4 +- 6 min, very…

(ABRIDGED) We present in detail our new 3D numerical models for the accretion of stellar winds on to Sgr A*. In our most sophisticated models, we put stars on realistic orbits around Sgr A*, include `slow' winds (300 km/s), and account for…

We performed the observation of the flux densities of SgrA* at 90 and 102GHz in order to detect the time lag between these frequencies using the Nobeyama Millimeter Array, which was previously reported at lower frequencies. We detected a…

In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. We find that the Sgr A* data exhibit variability that exceeds…

L'-band (lambda=3.8 microns) and M'-band (lambda=4.8 microns) observations of the Galactic Center region, performed in 2003 at VLT (ESO) with the adaptive optics imager NACO, have lead to the detection of an infrared counterpart of the…

Advances in VLBI instrumentation now allow wideband recording that significantly increases the sensitivity of short wavelength VLBI observations. Observations of the super-massive black hole candidate at the center of the Milky Way, SgrA*,…

Spectral and kinematic studies suggest that the nonthermal radio source Sgr A*, located at the center of the Milky Way, is a supermassive compact object with a mass 2-3 million solar masses. Winds from nearby stars, located approximately…

Proposed scaling relations of a characteristic timescale in the X-ray power spectral density of galactic and supermassive black holes have been used to argue that the accretion process is the same for small and large black holes. Here, we…

We present first results of JWST Cycle 1 and 2 observations of Sgr A* using NIRCam taken simultaneously at 2.1 and 4.8 micron for a total of ~48 hours over seven different epochs in 2023 and 2024. We find correlated variability at 2.1 and…

The discovery of radio pulsars in compact orbits around Sgr A* would allow an unprecedented and detailed investigation of the spacetime of the supermassive black hole. This paper shows that pulsar timing, including that of a single pulsar,…

Emission from Sgr A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ~20 years have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares…

We are fitting dynamics of electrically neutral hot-spot orbiting around Sgr A* source in Galactic center, represented by various modifications of the standard Kerr black hole (BH), to the three flares observed by the GRAVITY instrument on…

Over a two year period (1995-1997), we have conducted a diffraction-limited imaging study at 2.2 microns of the inner 6"x6" of the Galaxy's central stellar cluster using the Keck 10-m telescope. The K band images obtained reveal a large…

Although it is widely accepted that most galaxies have supermassive black holes (SMBHs) at their centers^{1-3}, concrete proof has proved elusive. Sagittarius A* (Sgr A*)^4, an extremely compact radio source at the center of our Galaxy, is…

Sgr A* is currently being fed by winds from a cluster of gravitationally bound young mass-loosing stars. Using observational constraints on the orbits, mass loss rates and wind velocities of these stars, we numerically model the…

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…

The emission region and black hole shadow of Sagittarius A*, the supermassive black hole at the Galactic Center, can be probed with millimeter Very Long Baseline Interferometry. Our goal is to probe the geometry of the emitting plasma…

We report the first detection of the Galactic Centre massive black hole, Sgr~A*, in the far infrared. Our measurements were obtained with PACS on board the \emph{Herschel} satellite at $100~\mathrm{\mu m}$ and $160~\mathrm{\mu m}$. While…