Variability Profiles of Millisecond X-Ray Pulsars: Results of Pseudo-Newtonian 3D MHD Simulations
arXiv:astro-ph/0507358 · doi:10.1086/444489
Abstract
We model the variability profiles of millisecond period X-ray pulsars. We performed three-dimensional magnetohydrodynamic simulations of disk accretion to millisecond period neutron stars with a misaligned magnetic dipole moment, using the pseudo-Newtonian Paczynski-Wiita potential to model general relativistic effects. We found that the shapes of the resulting funnel streams of accreting matter and the hot spots on the surface of the star are quite similar to those for more slowly rotating stars obtained from earlier simulations using the Newtonian potential. The funnel streams and hot spots rotate approximately with the same angular velocity as the star. The spots are bow-shaped (bar-shaped) for small (large) misalignment angles. We found that the matter falling on the star has a higher Mach number when we use the Paczynski-Wiita potential than in the Newtonian case. Having obtained the surface distribution of the emitted flux, we calculated the variability curves of the star, taking into account general relativistic, Doppler and light-travel-time effects. We found that general relativistic effects decrease the pulse fraction (flatten the light curve), while Doppler and light-travel-time effects increase it and distort the light curve. We also found that the light curves from our hot spots are reproduced reasonably well by spots with a gaussian flux distribution centered at the magnetic poles. We also calculated the observed image of the star in a few cases, and saw that for certain orientations, both the antipodal hot spots are simultaneously visible, as noted by earlier authors.
9 pages, 10 figures, accepted for publication in ApJ; corrected some typos
References in corpus (2)
Cited by in corpus (38)
- Accretion to Magnetized Stars through the Rayleigh-Taylor Instability: Global Three-Dimensional Simulations
- Unstable Disk Accretion to Magnetized Stars: First Global 3D MHD Simulations
- Light Curves for Rapidly-Rotating Neutron Stars
- Accreting millisecond pulsar SAX J1808.4-3658 during its 2002 outburst: evidence for a receding disc
- Spectral variability of classical T Tauri stars accreting in an unstable regime
- Accretion to Stars with Non-dipole Magnetic Fields
- Analytical Hot Spot Shapes and Magnetospheric Radius from 3D Simulations of Magnetospheric Accretion
- Boundary between Stable and Unstable Regimes of Accretion. Ordered and Chaotic Unstable Regimes
- Accretion, Outflows, and Winds of Magnetized Stars
- Accreting Millisecond X-Ray Pulsars
- Global 3D Simulations of Disc Accretion onto the classical T Tauri Star V2129 Oph
- Limits on Mass and Radius for the ms-Period X-ray Pulsar SAX J1808.4-3658
- MRI-driven Accretion on to Magnetized stars: Global 3D MHD Simulations of Magnetospheric and Boundary Layer Regimes
- Oscillations of MHD shock waves on the surfaces of T Tauri stars
- Constraints on the Properties of the Neutron Star XTE J1814-338 from Pulse Shape Models
- Accretion-powered millisecond pulsars
- Constraints on the Mass and Radius of the Neutron Star XTE J1807-294
- Timing an Accreting Millisecond Pulsar: Measuring the Accretion Torque in IGR J00291+5934
- Timing an Accreting Millisecond Pulsar: Measuring the Accretion Torque in IGR J00291+5934
- MRI-driven Accretion onto Magnetized stars: Axisymmetric MHD Simulations
- Global 3D Simulations of Disc Accretion onto the classical T Tauri Star BP Tauri
- Possible Quasi-Periodic Oscillations from Unstable Accretion: 3D MHD Simulations
- Measuring the spin up of the Accreting Millisecond Pulsar XTE J1751-305
- Bayesian parameter constraints for neutron star masses and radii using X-ray timing observations of accretion-powered millisecond pulsars
- Three-dimensional simulations of rotationally-induced line variability from a Classical T Tauri star with a misaligned magnetic dipole
- QPO emission from moving hot spots on the surface of neutron stars: a model
- Three-dimensional stability of magnetically confined mountains on accreting neutron stars
- GRMHD Simulations of Accreting Neutron Stars with Non-Dipole Fields
- Accretion onto Stars with Octupole Magnetic Fields: Matter Flow, Hot Spots and Phase Shifts
- On the nature of pulse profile variations and timing noise in accreting millisecond pulsars
- 2D and 3D MHD Simulations of Disk Accretion by Rotating Magnetized Stars: Search for Variability
- Effects of scattering in the accretion funnel on the pulse profiles of accreting millisecond pulsars
- MHD simulations of disk-star interaction
- Does the accreting millisecond pulsar XTE J1814-338 precess?
- Accurate analytical modeling of light rays in spherically symmetric spacetimes: Applications in the study of black hole accretion disks and polarimetry
- Finite size effects on the light curves of slowly-rotating neutron stars
- MRI: a possible mechanism for funnel flows?
- Fast and accurate analytical formulas for light propagation in general static, spherically symmetric spacetimes