Related papers: Evidence for Multiple Orbiting Hotspots in the 340…
A radio source at the Galactic center Sgr A* is a prime supermassive black hole candidate and therefore key to developing our understanding of them. Time variations in the 230 GHz band flux of Sgr A* have been found with the Atacama Large…
We study short-timescale 340 GHz flux-density variability of Sgr A* using ALMA Cycle 3 observations. Careful self-calibration enabled 10 s snapshot imaging with very high effective image-domain SNR, allowing high-cadence monitoring of…
The Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A*), in the Galactic Center on 2017 April 5-11 in the 1.3 millimeter wavelength band. At the same time, interferometric array data from the Atacama…
The supermassive black hole Sagittarius A* (Sgr A*) exhibits temporal and spectral variability across the electromagnetic spectrum. However, variability at radio frequencies below ~ 5 GHz for timescales shorter than a day remains largely…
We report on the final two days of a multiwavelength campaign of Sgr A* observing in the radio, submillimeter, infrared, and X-ray bands in July 2019. Sgr A* was remarkably active, showing multiple flaring events across the electromagnetic…
Results of two years of continuous monitoring of flux density variations at 8.3 and 2.3 GHz of the Galactic Center super-massive black hole candidate Sgr A* are reported. The average RMS modulation indices are 6% and 2.5% at 8.3 & 2.3 GHz…
Our aim is to characterize the polarized continuum emission properties including intensity, polarization position angle, and polarization percentage of Sgr A* at $\sim$100 (3.0 mm), $\sim$230 (1.3 mm), $\sim$345 (0.87 mm), $\sim$500 (0.6…
The compact radio source at the center of our Galaxy, Sagittarius A* (Sgr A*), is the subject of intensive study as it provides a close-up view of an accreting supermassive black hole. Sgr A* provides us with a prototype of a low-luminosity…
We present measurements with the VLBA of the variability in the centroid position of Sgr A* relative to a background quasar at 7-mm wavelength. We find an average centroid wander of 71 +/- 45 micro-arcsec for time scales between 50 and 100…
We analyzed 77 epochs of Atacama Large Millimeter/submillimeter Array (ALMA) archival data to investigate flux variability in Sagittarius A$^*$ (Sgr A$^*$), the supermassive black hole at the Galactic Center. Among these, we identified a…
We present 44 and 226 GHz observations of the Galactic center within 20$"$ of Sgr A*. Millimeter continuum emission at 226 GHz is detected from eight stars that have previously been identified at near-IR and radio wavelengths. We also…
We present the first detection from the Spitzer Space Telescope of 4.5 micron variability from Sgr A*, the emitting source associated with the Milky Way's central black hole. The >23 hour continuous light curve was obtained with the IRAC…
To understand the correlation and the radiation mechanism of flare emission in different wavelength bands, we have coordinated a number of telescopes to observe SgrA* simultaneously. We focus only on one aspect of the preliminary results of…
We performed the observation of the flux densities of Sgr A* at 90 and 102 GHz on 6 April 2005 using the Nobeyama Millimeter Array in order to detect the time lag between these frequencies. We constructed light curves covering a few hour…
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…
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…
Sgr A* is variable at radio and submillimeter wavelengths on hourly time scales showing time delays between the peaks of flare emission as well as linearly polarized emission at millimeter and sub-mm wavelengths. To determine the…
Radio and mm-wavelength observations of Sagittarius A* (Sgr A*), the radio source associated with the supermassive black hole at the center of our Galaxy, show that it behaves as a partially self-absorbed synchrotron-emitting source. The…
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…
We present the result of 6 years monitoring of SgrA*, radio source associated to the supermassive black hole at the centre of the Milky Way. Single dish observations were performed with the Itapetinga radio telescope at 7 mm, and the…