Related papers: Modeling of Disk-Star Interaction: Different Regim…
We report results from calculations investigating stationary magnetic field configurations in accretion discs around magnetised neutron stars. Our strategy is to start with a very simple model and then progressively improve it providing…
In this work we have estimated upper and lower limits to the strength of the magnetic dipole moment of all 14 accreting millisecond X-ray pulsars observed with the Rossi X-ray Timing Explorer (RXTE). For each source we searched the archival…
Some accreting neutron stars and young stars show unexplained episodic flares in the form of quasi-periodic oscillations or recurrent outbursts. In a series of two papers we present new work on an instability that can lead to episodic…
Accreting neutron stars differ from black holes by the presence of the star's own magnetic field, whose interaction with the accretion flow is a central component in understanding these systems' disk structure, outflows, jets, and spin…
Accretion of matter onto a magnetic, rotating object can be strongly affected by the interaction with its magnetic field. This occurs in a variety of astrophysical settings involving young stellar objects, white dwarfs, and neutron stars.…
A theoretical model for quasi-spherical subsonic accretion onto slowly rotating magnetized neutron stars is constructed. In this model the accreting matter subsonically settles down onto the rotating magnetosphere forming an extended…
Accretion of interstellar material by an isolated neutron star is discussed. The point I address here is the interaction between the accretion flow and the stellar magnetosphere. I show that the interchange instabilities of the…
Accretion onto a highly-magnetised neutron star runs through a magnetospheric flow, where the plasma follows the magnetic field lines in the force-free regime. The flow entering the magnetosphere is accelerated by the gravity of the star…
We present results of global three-dimensional (3D) magnetohydrodynamic (MHD) simulations of accretion onto magnetized stars where both the magnetic and rotational axes of the star are tilted about the rotational axis of the disc. We…
The accretion flow within the magnetospheric radius of bright X-ray pulsars can form an optically thick envelope, concealing the central neutron star from the distant observer. Most photons are emitted at the surface of a neutron star and…
Using the Rossi X-ray Timing Explorer (RossiXTE), astronomers have discovered that disk-accreting neutron stars with weak magnetic fields produce three distinct types of high-frequency X-ray oscillations. These oscillations are powered by…
Millisecond x-ray pulsars have weak magnetic dipole moments of $\sim 10^{16}$\,T\,m$^3$ compared to ordinary X-ray pulsars with dipole moments of $10^{20}$\,T\,m$^3$. For this reason a surrounding accretion disc can extend closer to the…
Quasi-spherical subsonic accretion onto slowly rotating magnetized NS is considered, when the accreting matter settles down subsonically onto the rotating magnetosphere, forming an extended quasi-static shell. The shell mediates the angular…
We discuss three specific modes of accretion disks around rotating magnetized neutron stars which may explain the separations of the kilo Hertz quasi periodic oscillations (QPO) seen in low mass X-ray binaries. The existence of these modes…
We perform MHD simulations of a thin resistive and viscous accretion disk around a neutron star with the surface dipolar magnetic field of 10$^8$ Gauss. The system evolution is followed during the interval of 500 millisecond pulsar…
Nuclear burning and its dependence on the mass accretion rate are fundamental ingredients for describing the complicated observational phenomenology of neutron stars in binary systems. Motivated by high quality burst rate data emerging from…
Accreting X-Ray Binaries display a wide range of behaviours. Some of them are observed to spin up steadily, others to alternate between spin-up and spin-down states, sometimes superimposed on a longer trend of either spin up or spin down.…
We present magnetohydrodynamic numerical simulations of the late post-supernova hypercritical accretion to understand its effect on the magnetic field of the new-born neutron star. We consider as an example the case of a magnetic field loop…
Global 3-D magnetohydrodynamical simulations have been conducted to study magnetospheric accretion around stars with various spin rates. For slow rotators, characterized by a fastness parameter $\omega_s\lesssim 0.78$, the disk's inner edge…
Accreting neutron stars can power a wide range of astrophysical phenomena including short- and long-duration gamma-ray bursts, ultra-luminous X-ray sources, and X-ray binaries. Numerical simulations are a valuable tool for studying the…