The Modulating Optical Depth of Photoelectric Absorption Edge with Pulse Phase in Accretion-Powered X-ray Pulsars
arXiv:1906.08037 · doi:10.3847/1538-4357/ab2b3d
Abstract
We report the first discovery of pulse phase modulating optical depths at the iron K-edge in accretion-powered X-ray pulsars, from Suzaku observations. A significant modulating optical depth of the iron K-edge is detected for Vela X-1 and GX 1+4. Similar trends are seen in GX 301-2 and OAO 1657-415, though with poor statistical significance. The observed iron K-edge exhibits a maximum optical depth, when the X-ray continuum dims, and there is no significant pulse phase variation in the ionization state of iron. The revealed changes in the optical depth with pulse phase can be explained as being due to the accreting matter captured by the magnetic field lines of the pulsar, which co-rotates with the neutron star spin and is responsible for photoelectric absorption. Based on the above interpretation, we propose that the accreting matter within the Alfvén radius contains iron with an ionization state of Fe with a particle density of cm and has a shape flattened along the azimuthal direction, such as an accretion curtain.
arXiv comment22pages, 13 figures, Accepted for publication in the Astrophysical Journal
References in corpus (29)
- The chemical composition of the Sun
- On the Absorption of X-rays in the Interstellar Medium
- Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
- Hard X-ray Detector (HXD) on Board Suzaku
- Monte-Carlo Simulator and Ancillary Response Generator of Suzaku XRT/XIS System for Spatially Extended Source Analysis
- Photoionization Modeling and the K Lines of Iron
- Relativistic Lines and Reflection from the Inner Accretion Disks Around Neutron Stars
- X-ray Spectral Study of the Photoionized Stellar Wind in Vela~X-1
- High variability in Vela X-1: giant flares and off states
- VLT/UVES spectroscopy of Wray 977, the hypergiant companion to the X-ray pulsar GX301-2
- New Evidence for Efficient Collisionless Heating of Electrons at the Reverse Shock of a Young Supernova Remnant
- Infrared Spectroscopy of Symbiotic Stars. IV. V2116 Ophiuchi/GX 1+4, The Neutron Star Symbiotic
- Orbital Decay and Evidence of Disk Formation in the X-ray Binary Pulsar OAO 1657-415
- Witnessing the magnetospheric boundary at work in Vela X-1
- Broadband spectroscopy using two Suzaku observation of the HMXB GX 301-2
- Data-oriented Diagnostics of Pileup Effects on the Suzaku XIS
- In Orbit Timing Calibration of the Hard X-Ray Detector on Board Suzaku
- Pulse phase and precession phase resolved spectroscopy of Her X-1: studying a representative Main-On with RXTE
- Short-Term Variability of X-rays from Accreting Neutron Star Vela X-1: I. Suzaku Observations
- Pulse phase resolved spectroscopy of Vela X-1 with Suzaku
- ASCA Observations of OAO 1657-415 and its Dust-Scattered X-Ray Halo
- Accretion column eclipses in the X-ray pulsars GX 1+4 and RX J0812.4-3114
- Variations in the pulsation and spectral characteristics of OAO 1657-415
- A Compton reflection dominated spectrum in a peculiar accreting neutron star
- A Suzaku View of Accretion Powered X-ray Pulsar GX 1+4
- Spectral variation in the X-ray pulsar GX 1+4 during a low-flux episode
- Phase-resolved spectral analysis of 4U 1901+03 during its outburst
- Suzaku observations of the 2013 outburst of KS 1947+300
- The Intensity Modulation of Fluorescent Line by a Finite Light Speed Effect in Accretion-Powered X-ray Pulsars