Related papers: Long time-scale variability in GRS1915+105
We report the results of 3 observations of GRS 1915+105 during which the source is found to show the X-ray dips/spike sequences (cycles). These observations were performed simultaneously with \integral, RXTE, the Ryle and Nancay radio…
The inspiral of supermassive black-hole binaries in gas-rich environment is driven by the presence of an accretion disc and viscous interactions tend to align the spin of the black holes with the orbital angular momentum of the disc. Recent…
abridged: We use XSCORT, together with the hydrodynamic accretion disc wind simulation from Proga & Kallman (2004), to calculate the impact that the accretion disk wind has on the X-ray spectrum from a 1E8 solar mass black hole Active…
Spectral features can arise by reflection of coronal X-rays on a black hole accretion disc. The resulting profile bears various imprints of strong gravitational field acting on the light emitting gas. The observed shape of the reflection…
Dark matter overdensities around black holes can alter the dynamical evolution of a companion object orbiting around it, and cause a dephasing of the gravitational waveform. Here, we present a refined calculation of the co-evolution of the…
We present the results of three-dimensional global resistive magnetohydrodynamic (MHD) simulations of black hole accretion flows. General relativistic effects are simulated by using the pseudo-Newtonian potential. Initial state is an…
Black hole impacts on accretion disks in galactic nuclei can power luminous transients, but predicting their observable signatures is challenging because the post-collision flow is highly time-dependent and inhomogeneous. We present a…
Recurring outbursts associated with matter flowing onto compact stellar remnants (black-holes, neutron stars, white dwarfs) in close binary systems, provide strong test beds for constraining the poorly understood accretion process. The…
Black hole X-ray binaries display significant stochastic variability on short time-scales (0.01-100 seconds), with a complex pattern of lags in correlated variability seen in different energy bands. This behaviour is generally interpreted…
The galactic superluminal motion source GRS 1915+105 was observed with RXTE at several occasions during its ongoing active state. The observed X-ray intensity changes drastically on a variety of time scales ranging from sub-seconds to days.…
Supergiant Fast X-ray Transients (SFXTs) represent the most extreme case of X-ray variability in High Mass X-ray Binaries hosting blue supergiant companions. Mainly discovered thanks to the INTEGRAL monitoring of the Galactic plane, these…
We perform hydro- and magnetohydrodynamical general relativistic simulations of a tidal disruption of a $0.1\,M_\odot$ red dwarf approaching a $10^5\,M_\odot$ non-rotating massive black hole on a close (impact parameter $\beta=10$)…
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…
Long-term ("superorbital") periods or modulations have been detected in a wide variety of both low and high-mass X-ray binaries at X-ray and optical wavelengths. A variety of mechanisms have been proposed to account for the variability…
The tidal disruption of a star around a supermassive black hole (SMBH) offers a unique opportunity to study accretion onto a SMBH on a human-timescale. We present results from our 1000+ days NICER, Swift and Chandra monitoring campaign of…
Explaining variability observed in the accretion flows of black hole X-ray binary systems remains challenging, especially concerning timescales less than, or comparable to, the viscous timescale but much larger than the inner orbital period…
We present a new way of looking at the very long term evolution of GRBs in which the disk of material surrounding the putative black hole powering the GRB jet modulates the mass flow, and hence the efficacy of the process that extracts…
The properties of sub-second time variability of the X-ray emission of the black-hole binary GRS 1915+105 are very complex and strictly connected to its patterns of variability observed on long time scales. A key aspect for determining the…
Radiation-driven outflows play a crucial role in extracting mass and angular momentum from binary systems undergoing rapid mass transfer at super-Eddington rates. To study the mass transfer process from a massive donor star to a…
Discerning the likelihood of the so-called runaway instability of thick accretion disks orbiting black holes is an important issue for most models of cosmic gamma-ray bursts. To this aim we investigate this phenomenon by means of…