相关论文: Sgr A* at low radio frequencies: GMRT observations

In this paper the jet model for the supermassive black hole candidate Sgr A* in the Center of the Galaxy is reviewed. The most recent model, with a reduced set of parameters, is able to account for all major radio properties of the source:…

Recent observations of the radio and NIR source Sgr A* reinforce the interpretation of the Galactic Center as a scaled down version of an AGN. The discovery of an elongated structure at 43 GHz and increasing evidence for the presence of an…

We observed Sgr A* and two extragalactic radio sources nearby in angle with the VLBA over a period of two years and measured relative positions with an accuracy approaching 0.1 mas. The apparent proper motion of Sgr A* relative to J1745-283…

We summarize basic observational results on Sagittarius~A* obtained from the radio, infrared and X-ray domain. Infrared observations have revealed that a dusty S-cluster object (DSO/G2) passes by SgrA*, the central super-massive black hole…

We analyze the gas and dust emission in the immediate vicinity of the supermassive black hole Sgr~A* at the Galactic center (GC) with the ESO VLT (Paranal/Chile) instruments SINFONI and VISIR. The SINFONI H+K data cubes show several…

We present new proper motion measurements and simultaneous orbital solutions for three newly identified (S0-16, S0-19, and S0-20) and four previously known (S0-1, S0-2, S0-4, and S0-5) stars at the Galactic Center. This analysis pinpoints…

The centre of our galaxy hosts the nearest super-massive black hole to the solar system, identified to the compact radio source Sgr A*. High energy experiments have tried in the past to detect the X/gamma-ray emission expected from the…

Sgr A* exhibits flares in radio, millimeter and submm wavelengths with durations of $\sim 1$ hour. Using structure function, power spectrum and autocorrelation function analysis, we investigate the variability of Sgr A* on time scales…

We present K-band $\lambda/\Delta\lambda$ ~ 2600 spectroscopy of five stars (K ~ 14 - 16 mag) within 0.''5 of Sgr A*, the radio source associated with the compact massive object suspected to be a 2.6 x 10$^{6}$ \msun black hole at the…

Recent broad-band 34 and 44 GHz radio continuum observations of the Galactic center have revealed 41 massive stars identified with near-IR counterparts, as well as 44 proplyd candidates within 30" of Sgr A*. Radio observations obtained in…

The cores of most galaxies are thought to harbour supermassive black holes, which power galactic nuclei by converting the gravitational energy of accreting matter into radiation (ref 1). Sagittarius A*, the compact source of radio, infrared…

A powerful outburst of X-ray radiation from the supermassive black hole Sgr A* at the center of the Milky Way is believed to be responsible for the illumination of molecular clouds in the central ~100 pc of the Galaxy (Sunyaev et al., 1993,…

We present gamma-ray observations with the LAT on board the Fermi Gamma-Ray Telescope of the nearby radio galaxy Centaurus~A. The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of…

The compact radio source Sgr A* is associated with a 3.6 million black hole at the center of the Milky Way. The radio source was discovered in February 1974 by Bruce Balick and Robert L.Brown. The National Radio Astronomy Observatory's…

We present a low frequency study of the diffuse radio emission in the galaxy cluster A754. We present new 150 MHz image of the galaxy cluster A754 made with the Giant Metrewave Radio Telescope (GMRT) and discuss the detection of 4 diffuse…

Using the JVLA, we explored the Galactic center (GC) with a resolution of 0.05" at 33.0 and 44.6 GHz. We detected 64 hyper-compact radio sources (HCRs) in the central parsec. The dense group of HCRs can be divided into three spectral types:…

Sagittarius A* is the source of near infrared, X-ray, radio, and (sub)millimeter emission associated with the supermassive black hole at the Galactic Center. In the submillimeter regime, Sgr A* exhibits time-variable linear polarization on…

The gas cloud G2 falling toward Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is supposed to provide valuable information on the physics of accretion flows and the environment of the black hole. We…

Synchrotron radiation from active galactic nuclei (AGN) is often highly polarized. We present a search for linear polarization with the Very Large Array (VLA) at 4.8 GHz and 8.4 GHz from the nearest AGN, Sagittarius A*. As a part of this…

Continuum low-frequency radio observations of the Galactic Center reveal the presence of two prominent radio sources, Sgr A East and its surrounding Halo, containing non-thermal particle distributions with power-law indices around 2.5-3.3…