The superorbital variability and triple nature of the X-ray source 4U 1820-303

Abstract

We perform a comprehensive analysis of the superorbital modulation in the ultracompact X-ray source 4U 1820-303, consisting of a white dwarf accreting onto a neutron star. Based on RXTE data, we measure the fractional amplitude of the source superorbital variability (with a 170-d quasi-period) in the folded and averaged light curves, and find it to be by a factor of about 2. As proposed before, the superorbital variability can be explained by oscillations of the binary eccentricity. We now present detailed calculations of the eccentricity-dependent flow through the inner Lagrangian point, and find a maximum of the eccentricity of about 0.004 is sufficient to explain the observed fractional amplitude. We then study hierarchical triple models yielding the required quasi-periodic eccentricity oscillations through the Kozai process. We find the resulting theoretical light curves to match well the observed ones. We constrain the ratio of the semimajor axes of the outer and inner systems, the component masses, and the inclination angle between the inner and outer orbits. Last but not least, we discover a remarkable and puzzling synchronization between the observed period of the superorbital variability (equal to the period of the eccentricity oscillations in our model) and the period of the general-relativistic periastron precession of the binary.

arXiv commentMNRAS, in press

References in corpus (24)

• A Double-Pulsar System - A Rare Laboratory for Relativistic Gravity and Plasma Physics
• Millisecond Oscillations in X-Ray Binaries
• On the Eccentricity Distribution of Coalescing Black Hole Binaries Driven by the Kozai Mechanism in Globular Clusters
• Photospheric radius expansion X-ray bursts as standard candles
• The Kozai Mechanism and the Evolution of Binary Supermassive Black Holes
• Four-Body Effects in Globular Cluster Black Hole Coalescence
• Warped accretion discs and the long periods in X-ray binaries
• Secular Evolution of Hierarchical Planetary Systems
• White Dwarf Donors in Ultracompact Binaries: The Stellar Structure of Finite Entropy Objects
• PSR J1756-2251: a new relativistic double neutron star system
• Six years of BeppoSAX Wide Field Cameras observations of nine galactic type-I X-ray bursters
• Correlation Between Energy Spectral States and Fast Time Variability and Further Evidence for the Marginally Stable Orbit in 4U 1820-30
• A Systematic Search for Periodicities in RXTE/ASM Data
• On the precession of accretion discs in X-ray binaries
• Binary and Long-Term (Triple?) Modulations of 4U 1820$-$30 in NGC 6624
• Formation of Ultracompact X-ray Binaries in Dense Star Clusters
• Time-Resolved Ultraviolet Observations of the Globular Cluster X-ray Source in NGC 6624: The Shortest Known Period Binary System
• RXTE Studies of Long-Term X-ray Spectral Variations in 4U 1820-30
• Periodic long-term X-ray and radio variability of Cygnus X-1
• Detection of highly ionized O and Ne absorption lines in the X-ray spectrum of 4U1820-303 in the globular cluster, NGC 6624
• Dependence of the orbital modulation of X-rays from 4U 1820-303 on the accretion rate
• On the nature of the flux variability during an expansion stage of a type I X-ray burst: Constraints on Neutron Star Parameters for 4U 1820-30
• Is There a Planet in the PSR 1620-26 Triple System?
• Eccentricity generation in hierarchical triple systems with coplanar and initially circular orbits

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