Related papers: Multiple accretion events as a trigger for Sgr A* …
Sgr A*, the putative black hole in our Galactic Center (GC), is extraordinary dim in all frequencies. Apparently the black hole is unable to accrete at the Bondi accretion rate for some reason. Another mystery of Sgr A* is the recently…
High resolution observations of Sgr A* have revealed a wide variety of phenomena, ranging from intense rapid flares to quasi-periodic oscillations, making this object an ideal system to study the properties of low luminosity accreting black…
The close neighbourhood of a supermassive black hole contains not only accreting gas and dust, but also stellar-sized objects like stars, stellar-mass black holes, neutron stars, and dust-enshrouded objects that altogether form a dense…
We study accretion rates during the gravitational wave-driven merger of a binary supermassive black hole embedded in an accretion disc, formed by gas driven to the centre of the galaxy. We use 3D simulations performed with PHANTOM, a…
Most of the local active galactic nucleus (AGN) population is obscured and much of the X-ray background originates in obscured AGNs. The contribution of obscured accretion to the growth of massive black holes is discussed here. The recent…
Stars orbiting within 1$\arcsec$ of the supermassive black hole in the Galactic Centre, Sgr A*, are notoriously difficult to detect due to obscuration by gas and dust. We show that some stars orbiting this region may be detectable via…
Several arguments suggest that stochastic condensation of cold gas and its accretion onto the central supermassive black hole (SMBH) is essential for active galactic nuclei (AGN) feedback to work in the most massive galaxies that lie at the…
It is often assumed that the strong gravitational field of a super-massive black hole disrupts an adjacent molecular cloud preventing classical star formation in the deep potential well of the black hole. Yet, young stars have been observed…
We have investigated the gas content of a sample of several hundred AGN host galaxies at z$<$1 and compared it with a sample of inactive galaxies, matched in bins of stellar mass and redshift. Gas masses have been inferred from the dust…
A cold neutral and extremely dim accretion disk may be present as a remnant of a past vigorous activity around the black hole in our Galactic Center (GC). Here we discuss ways to detect such a disk through its interaction with numerous…
Sagittarius A* (Sgr A*) is a compact radio source at the Galactic center. Observations have confirmed that its mass is approximately (4.1)*10$^{6}$ M$_{\odot}$, and Sgr A* is generally believed to be powered by gas accretion onto a…
We consider here the collective accretion of gas by globular clusters and dwarf galaxies moving through the interstellar medium. In the limit of high velocity and/or sound speed of the ISM, the collective potential of the cluster is…
We investigate the origin and fate of the recently discovered gas cloud G2 close to the Galactic Center. Our hydrodynamical simulations focussing on the dynamical evolution of the cloud in combination with currently available observations…
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…
The galactic black hole binary systems give an observational template showing how the accretion flow changes as a function of increasing mass accretion rate, or L/L_Edd. These data can be synthetised with theoretical models of the accretion…
We consider a model in which Sgr A*, the 3.5x10^6 M_sun supermassive black hole candidate at the Galactic Center, is a compact object with a surface. Given the very low quiescent luminosity of Sgr A* in the near infrared, the existence of a…
Sub milli-arcsecond astrometry and imaging of the black hole Sgr A* at the Galactic centre may become possible in the near future at infrared and sub-millimetre wavelengths. Motivated by observations of short-term infrared and X-ray…
We revisit theoretical and observational constraints on geometrically-thin disk accretion in Sagittarius A* (Sgr A*). We show that the combined effects of mass outflows and electron energization in the hot part of the accretion flow can…
Using parsec scale resolution hydrodynamical adaptive mesh refinement simulations we have studied the mass transport process throughout a galactic merger. The aim of such study is to connect both the peaks of mass accretion rate onto the…
We propose a scenario in which massive stars form in a self-gravitating gaseous disc around a supermassive black hole. We find that once the surface density of the disc exceeds a critical value, the disc fragments into dense clumps. The…