Related papers: Settling accretion onto slowly rotating X-ray puls…
In addition to coherent pulsation, many accreting neutron stars exhibit flaring activity and strong aperiodic variability on time scales similar to or shorter than their pulsation period. Such a behavior shows that the accretion flow in the…
Quasi-spherical supersonic (Bondi-type) accretion to a star with a dipole magnetic field is investigated using resistive magnetohydrodynamic simulations. A systematic study is made of accretion to a non-rotating star, while sample results…
In regions of star formation, protostars and newborn stars accrete mass from their natal clouds. These clouds are threaded by magnetic fields with a strength characterized by the plasma beta---the ratio of thermal and magnetic pressures.…
We propose a novel theoretical model to describe a physical identity of the soft X-ray excess, ubiquitously detected in many Seyfert galaxies, by considering a steady-state, axisymmetric plasma accretion within the innermost stable circular…
Recent observations suggest that neutron stars in low-mass X-ray binaries rotate within a narrow range of spin frequencies clustered around 300 Hz. A proposed explanation for this remarkable fact is that gravitational radiation from a…
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…
3D Magnetohydrodynamic simulations show that when matter accretes onto neutron stars, in particular if the misalignment angle is small, it does not constantly fall at a fixed spot. Instead, the location at which matter reaches the star…
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…
We investigate whether the intrinsic spin of neutron stars leaves an observable imprint on the spectral properties of X-ray binaries. To evaluate this we consider a sample of nine NSs for which the spins have been measured that are not…
Supergiant High Mass X-ray Binary systems (sgHMXBs) consist of a massive, late type, star and a neutron star. The massive stars exhibits strong, radiatively driven, stellar winds. Wind accretion onto compact object triggers X-ray emission,…
Some thermonuclear (type I) X-ray bursts at the neutron star surfaces in low-mass X-ray binaries take place during hard persistent states of the systems. Spectral evolution of these bursts is well described by the atmosphere model of a…
Recent theoretical work has made it plausible for neutron stars (NSs) to lose angular momentum via gravitational radiation on long timescales (around Myrs) while actively accreting. The gravitational waves (GWs) can either be emitted via…
Recent spectropolarimetric observations suggest that young low-mass stars such as classical T Tauri stars (CTTSs) possess relatively strong (~kG) magnetic field. This supports a scenario in which the final accretion onto the stellar surface…
We consider combined rotational, magnetic, and thermal evolution of the neutron star during the accretion phase in a binary system. A rapid accretion-driven decay of the magnetic field decreases substantially the efficiency of angular…
It was pointed out by Paczynski (1987) that the X-ray luminosity of accreting neutron stars is very sensitive to the physical properties of the accretion flow close to the innermost stable circular orbit. The X-ray radiation is dominated by…
The distribution of the spin frequencies of neutron stars in low-mass X-ray binaries exhibits a cut-off at 730 Hz, below the break-up frequency (mass-shedding limit) of neutron stars. The absence of the sub-millisecond pulsars presents a…
The spin behaviour of the neutron star in the newly discovered young Be/X-ray long-period pulsar SXP 1062 is discussed. The star is observed to rotate with the period of 1062s, and spin-down at the rate ~ - 2.6 \times 10^{-12} Hz s^{-1}. I…
We analyze archival Chandra HRC observations of the ultra luminous accreting pulsar M82-X2 (NuSTAR J095551+6940.8), and determine an upper limit of $< 1.7\times 10^{38}$~erg/s to its luminosity at an epoch at which it was undetected.…
In classical supergiant X-ray binaries (SgXBs), the Bondi-Hoyle-Lyttleton wind accretion was usually assumed, and the angular momentum transport to the accretors is inefficient. The observed spin-up/spin-down behavior of the neutron star in…
We calculate the nucleosynthesis during stable nuclear burning on an accreting neutron star. This is appropriate for weakly magnetic neutron stars accreting at near-Eddington rates in low mass X-ray binaries, and for most accreting X-ray…