Evolution of intermediate-mass X-ray binaries driven by magnetic braking of Ap/Bp stars: I. ultracompact X-ray binaries

Abstract

It is generally believed that Ultracompact X-ray binaries (UCXBs) evolved from binaries consisting of a neutron star accreting from a low-mass white dwarf or helium star where mass transfer is driven by gravitational radiation. However, the standard white-dwarf evolutionary channel cannot produce the relatively long-period ($40-60$\,min) UCXBs with high time-averaged mass-transfer rate. In this work, we explore an alternative evolutionary route toward UCXBs where the companions evolve from intermediate-mass Ap/Bp stars with an anomalously strong magnetic field ($100-10000$\,G). Including the magnetic braking caused by the coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accreting component, we show that intermediate-mass X-ray binaries (IMXBs) can evolve into UCXBs. Using the \emph{MESA} code, we have calculated evolutionary sequences for a large number of IMXBs. The simulated results indicate that, for a small wind-driving efficiency $f=10^{-5}$, the anomalous magnetic braking can drive IMXBs to an ultra-short period of 11 min. Comparing our simulated results with the observed parameters of fifteen identified UCXBs, the anomalous magnetic braking evolutionary channel can account for the formation of seven and eight sources with $f=10^{-3}$, and $10^{-5}$, respectively. In particular, a relatively large value of $f$ can fit three of the long-period, persistent sources with high mass-transfer rate. Though the proportion of Ap/Bp stars in intermediate-mass stars is only 5\%, the lifetime of the UCXB phase is $\gtrsim$ 2 Gyr, producing a relatively high number of observable systems, making this an alternative evolutionary channel for the formation of UCXBs.

10 pages, 9 figures, 2 tables, accepted for publication in ApJ

References in corpus (6)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Optical spectroscopy of (candidate) ultra-compact X-ray binaries: constraints on the composition of the donor stars
• The Galactic Gravitational wave foreground
• Population synthesis of ultracompact X-ray binaries in the Galactic Bulge
• Time-resolved optical photometry of the ultra-compact binary 4U0614+091
• Long-term luminosity behavior of 14 ultracompact X-ray binaries

Cited by in corpus (23)

• The effects of surface fossil magnetic fields on massive star evolution: I. Magnetic field evolution, mass-loss quenching and magnetic braking
• Formation of millisecond pulsars with helium white dwarfs, ultra-compact X-ray binaries and gravitational wave sources
• The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars
• Magnetic braking saturates: evidence from the orbital period distribution of low-mass detached eclipsing binaries from ZTF
• The Effect of Transient Accretion on the Spin-Up of Millisecond Pulsars
• Ultra-compact X-ray binaries with He star companions
• Novel modelling of ultra-compact X-ray binary evolution - stable mass transfer from white dwarfs to neutron stars
• Ultra-compact X-ray binaries as dual-line gravitational-wave sources
• Effects of Irradiation on the Evolution of Ultra-compact X-ray Binaries
• On the progenitors of AM CVn stars as LISA sources: the evolved donor star channel
• Fast orbital shrinkage of black hole X-ray binaries driven by circumbinary disks
• Black Hole Ultra-compact X-ray Binaries: Galactic Low-Frequency Gravitational Wave Sources
• Investigating cannibalistic millisecond pulsar binaries using MESA: New constraints from pulsar spin and mass evolution
• Spin evolution of neutron stars in two modes: implication for millisecond pulsars
• Formation of Sco X-1 induced by anomalous magnetic braking of Ap/Bp stars
• The X-ray Binary-Star Cluster Connection in Late-Type Galaxies
• A Circumbinary Disk Scenario For The Negative Orbital-Period Derivative Of The Ultracompact X-ray Binary 4u1820-303
• Anomalous orbital expansion of low-mass X-ray binary 2A 1822-371: the existence of a circumbinary disk?
• Algorithms and radiation dynamics for the vicinity of black holes I. Methods and codes
• The first extragalactic ultra-compact X-ray binary : a candidate black hole-white dwarf system
• Ultra-compact X-ray Binaries: A Review
• Can the Anomalous Magnetic Braking of Ap/Bp Stars Explain the Orbital Decay of Algol-type Binaries?
• Mechanisms for magnetic braking boost and disruption: the role of irradiation-driven winds and convective turnover time spike in cataclysmic variables