Related papers: Quasi-spherical accretion in X-ray pulsars
We study the current sample of rapidly rotating neutron stars in both accreting and non-accreting binaries in order to determine whether the spin distribution of accreting neutron stars in low-mass X-ray binaries can be reconciled with…
Different accretion regimes onto magnetized NSs in HMXBs are considered: wind-fed supersonic (Bondi) regime at high accretion rates $\dot M\gtrsim 4\times 10^{16}$~[g s$^{-1}$] , subsonic settling regime at lower $\dot M$ and supercritical…
When an accreting star is close to rotational equilibrium between the dipole component of the stellar magnetic field and the accretion disk, the star's rotation rate is roughly of the order of the Keplerean rotation rate at the inner…
Thermal radiation of neutron stars in soft X-ray transients (SXTs) in a quiescent state is believed to be powered by the heat deposited in the stellar crust due to nuclear reactions during accretion. Confronting observations of this…
Accreting X-ray pulsars, located in X-ray binaries, are neutron stars with magnetic fields as strong as $B\sim10^{12\text{--}13}$ G. This review offers a concise overview of the accretion and radiation processes of X-ray pulsars and…
Supergiant fast X-ray transients (SFXTs) are characterized by a remarkable variability in the X-ray domain, widely ascribed to the accretion from a clumpy stellar wind. In this paper we performed a systematic and homogeneous analysis of…
The appearance and time variability of accreting millisecond X-ray pulsars (hereafter AMXPs, e.g. Wijnands & van der Klis 1998) depends strongly on the accretion rate, the effective viscosity and the effective magnetic diffusivity of the…
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 discovery of the ultraluminous X-ray pulsar M82 X-2 has stimulated lively discussion on the nature of the accreting neutron star. In most of the previous studies the magnetic field of the neutron star was derived from the observed…
A numerical rotating neutron star solver is used to study the temporal evolution of accreting neutron stars using a multi-polytrope model for the nuclear equation of state named ACB5. The solver is based on a quadrupole expansion of the…
Weakly magnetic, millisecond spinning neutron stars attain their very fast rotation through a 1E8-1E9 yr long phase during which they undergo disk-accretion of matter from a low mass companion star. They can be detected as accretion-powered…
We explore the possibility to explain the properties of the Be/X-ray pulsars observed in the Small Magellanic Cloud within the magnetic levitation accretion scenario. This implies that their X-ray emission is powered by a wind-fed accretion…
Modelling of thermonuclear X-ray bursts on accreting neutron stars has to date focused on stable accretion rates. However, bursts are also observed during episodes of transient accretion. During such events, the accretion rate can evolve…
We present estimates for the accretion rates in 13 X--ray bursting sources which exhibit photospheric expansion, basing on theoretical models of stationary, radiatively driven winds from neutron stars. The relatively high values obtained,…
The accretion-powered, X-ray pulsar 4U 1626-67 has recently shown an abrupt torque reversal accompanied by a dramatic spectral transition and a relatively small luminosity change. The time-averaged X-ray spectrum during spin-down is…
A hyperaccretion flow around a stellar mass black hole is thought to be the most plausible engine that powers gamma-ray bursts (GRBs). The flow efficiently cools via neutrino emission at >~ 0.003-0.01 M_sun s^{-1} (corresponding to a…
We discuss the recent efforts to use a sub-class of neutron-star X-ray transients (the quasi-persistent transients) to probe the properties of neutron-star crusts and cores. Quasi-persistent X-ray transients experience accretion episodes…
The propeller regime of disk accretion to a rapidly rotating magnetized star is investigated here for the first time by axisymmetric 2.5D magnetohydrodynamic simulations. An expanded, closed magnetosphere forms in which the magnetic field…
Assuming that AXPs and SGRs accrete matter from a fallback disk, we attempt to explain both the soft and the hard X-ray emission as the result of the accretion process. We also attempt to explain their radio emission or the lack of it. We…
Nuclear reactions in accreting neutron-star crusts and the heat release accompanying them are studied, under different assumptions concerning the composition of the outermost layer formed of the ashes of X-ray bursts. Particular examples of…