Related papers: The Galactic Center stellar cluster: The central a…
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…
We have made angular broadening measurements in the satellite line of the OH molecule at 1612 MHz of 8 OH/IR stars located near the Galactic Center with the Very Large Array. Early observations with the Very Long Baseline Array had revealed…
Bright Active Galactic Nuclei are powered by accretion of mass onto the super massive black holes at the centers of the host galaxies. For fainter objects star formation may significantly contribute to the luminosity. We summarize…
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…
The properties of the stellar cluster surrounding Sagittarius A* can be assessed indirectly through the motion of the S-stars. Specifically, the current accuracy to which the prograde precession of the S2 star is measured allows to place…
This paper has been withdrawn temporarily by the authors. As stars close to the galactic centre have short orbital periods it has been possible to trace large fractions of their orbits in the recent years. Previously the data of the orbit…
Sagittarius A* (Sgr A*), the supermassive black hole at the heart of our galaxy, provides unique opportunities to study black hole accretion, jet formation, and gravitational physics. The rapid structural changes in Sgr A*'s emission pose a…
A preliminary estimation of gravitational waves (GWs) from the extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is given for the 37 observed S-stars revolving around the supermassive black hole (SMBH) at Sagittarius…
The orbit of the S2 star around Sagittarius A* provides a unique opportunity to test general relativity and study dynamical processes near a supermassive black hole. Observations have shown that the orbit of S2 is consistent with a…
We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between…
The existence of a massive black hole in the center of the Milky Way, coinciding with the radio source Sgr A*, is being established on more and more solid ground. In principle, this black hole, acting as a gravitational lens, is able to…
The Center of our Galaxy is a peculiar region where a number of crucial astrophysical phenomena take place, from star formation to SN explosions and accretion onto a massive black hole. The quest for a massive black hole in the Galactic…
Supermassive black holes in the centre of galaxies dominate the gravitational potential of their surrounding stellar clusters. In these dense environments, stars follow nearly Keplerian orbits, which get slowly distorted as a result of the…
We present improved relative astrometry for stars within the central half parsec of our Galactic Center based on data obtained with the 10 m W. M. Keck Observatory from 1995 to 2017. The new methods used to improve the astrometric precision…
Gas clouds are present in the Galactic centre, where they orbit around the supermassive black hole. Collisions between these clumps reduce their angular momentum, and as a result some of the clumps are set on a plunging trajectory.…
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…
We present a new geometrical method for measuring the distance to the Galactic center (R_0) by solving for the Keplerian orbit of individual stars bound to the black hole associated with the Sgr A* from radial velocity and proper motion…
The center of our galaxy hosts Sagittarius~A*, a supermassive compact object of $\sim 4.3\times 10^6$ solar masses, usually associated with a black hole. Nevertheless, black holes possess a central singularity, considered unphysical, and an…
The presence of massive stars (MSs) in the region close to the Galactic Center (GC) poses several questions about their origin. The harsh environment of the GC favors specific formation scenarios, each of which should imprint characteristic…
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…