Related papers: Examining molecular clouds in the Galactic Centre …
X-ray reflection off dense molecular clouds in the Galactic Centre region has established itself as a powerful probe for the past activity record of the supermassive black hole Sgr A* on a timescale of a few hundred years. Detailed studies…
Viscous rotating accretion flows around black holes become advection-dominated when the accretion rate $\dot M$ is sufficiently low. Most of the accretion energy in such flows is stored within the gas and advected radially inward. The…
We report the detection of Sagittarius A*, the radio source associated with our Galaxy's central massive black hole, at 330 MHz with the Very Large Array. Implications for the spectrum and emission processes of Sagittarius A* are discussed…
We present the ASCA results of imaging spectroscopy of the giant molecular cloud Sgr B2. The X-ray spectrum is found to be very peculiar; it exhibits a strong emission line at 6.4 keV, a low energy cutoff below about 4 keV and a pronounced…
Reflection of X-ray emission on molecular clouds in the inner $\sim$ 100 pc of our Galaxy reveals that, despite being extremely quiet at the moment, our supermassive black hole Sgr A* should have experienced bright flares of X-ray emission…
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.…
X-ray flares have routinely been observed from the supermassive black hole, Sagittarius A$^\star$ (Sgr A$^\star$), at our Galactic center. The nature of these flares remains largely unclear, despite of many theoretical models. In this…
The evidence for the presence of a concentration of dark matter at the Galactic center is now very compelling. There is no question that the stellar and gas kinematics within 0.01 pc is dominated by under-luminous matter in the form of…
We developed a numerical methodology to compute the fully-relativistic propagation time of photons emitted by a pulsar in orbit around a massive compact object, like the supermassive black hole Sagittarius A* in the Galactic Center, whose…
Assuming that the compact source at the Galactic center, Sagittarius A*, is a massive boson star, we fit the near-infrared flare astrometry data. We consider 12 discrete boson star configurations and model the flare as a hotspot on a…
The dark compact object at the centre of the Milky Way is well established to be a supermassive black hole with mass $M_{\bullet} \sim 4.3 \cdot 10^6 \, M_{\odot}$, but the nature of its environment is still under debate. In this work, we…
The giant molecular cloud complex Sagittarius B2 (Sgr~B2) in the central molecular zone of our Galaxy hosts several high-mass star formation sites, with Sgr~B2(M) and Sgr~B2(N) being the main centers of activity. This analysis aims to…
In spite of increasing evidences of the presence of a massive Black Hole at the Galactic Center, its radio counterpart, Sgr A*, shows little activity at high energies, and recent models involving energy advection (ADAF) have been proposed…
We report on a successful, simultaneous observation and modelling of the millimeter (mm) to near-infrared (NIR) flare emission of the Sgr A* counterpart associated with the supermassive black hole at the Galactic centre (GC). We present a…
Context. We present the results of a multi-year monitoring campaign of the Galactic Center (GC) with the MAGIC telescopes. These observations were primarily motivated by reports that a putative gas cloud (G2) would be passing in close…
The detection of a pulsar closely orbiting our Galaxy's supermassive black hole - Sagittarius A* - is one of the ultimate prizes in pulsar astrophysics. The relativistic effects expected in such a system could far exceed those currently…
We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr A* has been conducted through surveys over a wide range of…
We present results of our Chandra observation with the ACIS-I instrument centered on the position of Sagittarius A* (Sgr A*), the compact nonthermal radio source associated with the massive black hole (MBH) at the dynamical center of the…
We present general relativistic magnetohydrodynamic (GRMHD) numerical simulations of the accretion flow around the supermassive black hole in the Galactic centre, Sagittarius A* (Sgr A*). The simulations include for the first time radiative…
The fluorescent X-ray emission from neutral iron in the molecular clouds (Sgr B) indicates that the clouds are being irradiated by an external X-ray source. The source is probably associated with the Galactic central black hole (Sgr A*),…