Torque reversals and wind variations of X-ray pulsar Vela X-1
arXiv:2210.02032 · doi:10.1093/mnrasl/slac119
Abstract
The erratic spin history of Vela X-1 shows some continuous spin-up/spin-down trend over tens of days. We study the orbital profile and spectral property of Vela X-1 in these spin-up/spin-down intervals, using the spin history monitored by Fermi/GBM and light curve from Swift/BAT and MAXI/GSC. The BAT fluxes in the spin-up intervals are about 1.6 times those of the spin-down intervals for out-of-eclipse orbital phases. The spin-up intervals also show a higher column density than the spin-down intervals, indicating there are more material on the orbital scale for the spin-up intervals. It could be due to the variation of the stellar wind of the optical star (HD 77581) on tens of days. The varying wind could lead to alternating prograde/retrograde accreting flow to the neutron star, which dominates the transfer of the angular momentum to Vela X-1, but not the total observed luminosity.
arXiv comment5 pages, 5 figs, to appear on MNRAS Letters
References in corpus (19)
- The Fermi Gamma-Ray Burst Monitor
- Observations of Accreting Pulsars
- The Swift/BAT Hard X-ray Transient Monitor
- Theory of quasi-spherical accretion in X-ray pulsars
- Gas Slit Camera (GSC) onboard MAXI on ISS
- The ephemeris, orbital decay, and masses of 10 eclipsing HMXBs
- Towards a unified view of inhomogeneous stellar winds in isolated supergiant stars and supergiant high mass X-ray binaries
- High variability in Vela X-1: giant flares and off states
- On the Correlation of Torque and Luminosity in GX 1+4
- The Ups & Downs of Accreting X-Ray Pulsars: Decade-long observations with the Fermi Gamma-Ray Burst Monitor
- Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in Supergiant Fast X-ray Transient and classical Supergiant X-ray Binaries
- Coupling hydrodynamics with comoving frame radiative transfer: II. Stellar wind stratification in the high-mass X-ray binary Vela X-1
- Formation of wind-captured discs in Supergiant X-ray binaries : consequences for Vela X-1 and Cygnus X-1
- Revisiting the archetypical wind accretor Vela X-1 in depth -- A case study of a well-known X-ray binary and the limits of our knowledge
- Stellar wind accretion and accretion disk formation: applications to neutron star high mass X-ray binaries
- Footprints in the wind of Vela X-1 traced with MAXI
- Spectral evidence of an accretion disk in wind-fed X-ray pulsar Vela X-1 during an unusual spin-up period
- Detection of nearly periodic spin period reversals in Vela X-1 on long time-scales: inkling of solar-like cycle in the donor star?
- Torque reversal and orbital profile of X-ray pulsar OAO 1657-415