Related papers: Selfgravity and QSO disks
We present a possible explanation for the high-frequency Quasi-Periodic Oscillations of microquasars by an MHD instability that combines the physics developed, in different contexts, for the Accretion-Ejection Instability, the Rossby-Wave…
(Abridged) We study the dynamical evolution of a stationary, axisymmetric, and perfectly conducting cold accretion disk containing a large-scale magnetic field around a Kerr black hole, trying to understand the relation between accretion…
We study the force balance and resulting acceleration of gas in general relativity basing on simulations of accretion on a stellar-mass, non-rotating black hole. We compare properties of acceleration in an optically thin, radiatively…
We perform general relativistic simulations of self-gravitating black hole-disks in which the spin of the black hole is significantly tilted ($45^\circ$ and $90^\circ$) with respect to the angular momentum of the disk and the disk-to-black…
Supermassive black holes in galaxy centres can grow by the accretion of gas, liberating energy that might regulate star formation on galaxy-wide scales. The nature of the gaseous fuel reservoirs that power black hole growth is nevertheless…
QSOs allow study of the evolution of the relationship between black holes in galactic nuclei and their host galaxies. The black hole mass can be derived from the widths of the broad emission lines, and the stellar velocity dispersion…
The QSO lifetime t_Q is one of the most fundamental quantities for understanding black hole and QSO evolution, yet it remains uncertain by several orders of magnitude. If t_Q is long, then only a small fraction of galaxies went through a…
QSO emission-line spectra are compared to predictions based on theoretical ionizing continua of accretion disks. Observed line intensities do not show the expected trend of higher ionization with higher accretion disk temperature as derived…
Theoretically, inflowing filaments of gas are one of the main causes of growth for a galaxy. Nonetheless, observationally, probing ongoing gas accretion is challenging. As part of the Gas Stripping Phenomena in galaxies with MUSE (GASP)…
According to the traditional scenario for core-collapse supernovae, the core of the collapsing star forms a neutron star and its gravitational energy release sends out a shockwave into the stellar envelope. However, in a significant number…
Early in the study of viscous accretion disks it was realized that energy transfers from distant sources must be important, not least because the flow at the disk midplane in the bulk of the disk is likely outwards, out of the gravitational…
We study gravitational-wave emission by turbulent flows in accretion disks around spinning black holes or neutron stars. We aim to understand how turbulence can stochastically excite black hole quasinormal ringing and contribute to a…
Throughout the Hubble time, gas makes its way from the intergalactic medium into galaxies fuelling their star formation and promoting their growth. One of the key properties of the accreting gas is its angular momentum, which has profound…
In this chapter, I present a summary of observational tests of the basic picture of disk accretion. An emphasis is placed on tests relevant to black holes, but many of the fundamental results are drawn from studies of other classes of…
We study numerically the axisymmetric relativistic Bondi-Hoyle accretion of a supersonic ideal gas onto a fixed Schwarzschild background space-time described with horizon penetrating coordinates. We verify that a nearly stationary shock…
The thickness of a slim disk is determined by the balance between the radiation force and the vertical component of the gravity of the black hole (BH). It was found that vertical gravity increases with the disk height, and it will decrease…
Theoretical studies of transonic accretion onto black holes reveal a wide range of possible solutions, broadly classified into smooth flows and flows featuring shocks. Accretion solutions that involve the formation of shocks are…
There is a maximum for the gravity of a black hole in the vertical direction in the accretion disc. Outflows may probably be driven from the disc if the radiation flux of the disc is greater than a critical value corresponding to the…
HST observations of some QSOs show a strong, abrupt increase in polarization at rest wavelength about 750 A, suggestive of a connection with the Lyman edge of hydrogen. Blaes and Agol (1996) have proposed an explanation in terms of stellar…
We report on the first phase of our study of slightly rotating accretion flows onto black holes. We consider inviscid accretion flows with a spherically symmetric density distribution at the outer boundary, but with spherical symmetry…