Related papers: Limits on the Position Wander of Sgr A*
The preliminary detection of the Galactic Center black hole Sgr A* in X-rays by the Chandra mission, as well as recent mm-VLBI measurements, impose strict constraints on this source. Using a relativistic jet model for Sgr A*, we calculate…
New observations of Sgr A have been carried out with the VLA using the broadband (2 GHz) continuum mode at 5.5 GHz, covering the central 30 pc region of the RBZ at the Galactic center. Using the MS-MFS algorithms in CASA, we have imaged Sgr…
Recent millimeter-VLBI observations of Sagittarius A* (Sgr A*) have, for the first time, directly probed distances comparable to the horizon scale of a black hole. This provides unprecedented access to the environment immediately around the…
The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. We combine radio-wave scattering data and free-free emission…
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…
(abridged) The massive black hole at the center of the Milky Way, SagittariusA* is, in relative terms, the weakest accreting black hole accessible to observations. At the moment, the mean SED of SgrA* is only known reliably in the radio to…
Sgr A* is the variable electromagnetic source associated with accretion onto the Galactic center supermassive black hole. While the near-infrared (NIR) variability of Sgr A* was shown to be consistent over two decades, unprecedented…
Images from the vicinity of the black hole horizon at the Galactic centre (Sgr A*) could be obtained in the near future with a Very Large Baseline Array of sub-millimetre telescopes. The recently observed short-term infrared and X-ray…
Near-IR and X-ray flares have been detected from the supermassive black hole Sgr A* at the center of our Galaxy with a (quasi)-period of ~17-20 minutes, suggesting an emission region only a few Schwarzschild radii above the event horizon.…
Radio images of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), are dominated by interstellar scattering. Previous studies of Sgr A* have adopted an anisotropic Gaussian model for both the intrinsic source and the…
We present the results of radio monitoring observations of Sgr A* at 7 mm (i.e. 43 GHz) with VLBI Exploration of Radio Astrometry (VERA), which is a VLBI array in Japan. VERA provides angular resolutions on millisecond scales, resolving…
The Galactic Center supermassive black hole Sagittarius A* (Sgr A*) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm…
Very strong evidence suggests that Sagittarius A*, a compact radio source at the center of the Milky Way, marks the position of a super massive black hole. The proximity of Sgr A* in combination with its mass makes its apparent event…
The modern accuracy of measurements allows the residual/peculiar (Galactocentric) velocity of the supermassive black hole (SMBH) in our Galaxy, Sgr A*, on the order of several kilometers per second. We integrate possible orbits of the SMBH…
We examine time-dependent 2D relativistic radiation MHD flows to develop the shock oscillation model for the long-term flares of Sgr A*. Adopting modified flow parameters in addition to the previous studies, we confirm quasi-periodic flares…
Sagittarius A* (Sgr A*) is a strong, compact radio source believed to be powered by a super-massive black hole at the galactic center. Extinction by dust and gas in the galactic plane prevents observing it optically, but its position and…
The X-ray mission Chandra has observed a dramatic X-ray flare -- a brightening by a factor of 50 for only three hours -- from Sgr A*, the Galactic Center supermassive black hole. Sgr A* has never shown variability of this amplitude in the…
Multiwavelength monitoring observations of Sagittarius A* exhibit variability on timescales of minutes to hours, indicating emission regions localized near the event horizon. (Sub)Millimeter-wavelength VLBI is uniquely suited to probe the…
We study the environment of Sgr A* using spectral and continuum observations with the ALMA and VLA. Our analysis of sub-arcsecond H30alpha, H39alpha, H52alpha and H56alpha line emission towards Sgr A* confirm the recently published broad…
General relativity makes clear predictions about the spacetime geometry around black holes. In the near future, new facilities will have the capability to explore the metric around SgrA$^*$, the supermassive black hole candidate at the…