English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

It is generally believed that Ultracompact X-ray binaries (UCXBs) evolvedfrom binaries consisting of a neutron star accreting from a low-mass whitedwarf or helium star where mass transfer is driven by gravitational radiation.However, the standard white-dwarf evolutionary channel cannot produce therelatively long-period ($40 - 60$\,min) UCXBs with high time-averagedmass-transfer rate. In this work, we explore an alternative evolutionary routetoward UCXBs where the companions evolve from intermediate-mass Ap/Bp starswith an anomalously strong magnetic field ($100 - 10000$\,G). Including themagnetic braking caused by the coupling between the magnetic field and anirradiation-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 alarge number of IMXBs. The simulated results indicate that, for a smallwind-driving efficiency $f=10^{-5}$, the anomalous magnetic braking can driveIMXBs to an ultra-short period of 11 min. Comparing our simulated results withthe observed parameters of fifteen identified UCXBs, the anomalous magneticbraking evolutionary channel can account for the formation of seven and eightsources with $f=10^{-3}$, and $10^{-5}$, respectively. In particular, arelatively large value of $f$ can fit three of the long-period, persistentsources with high mass-transfer rate. Though the proportion of Ap/Bp stars inintermediate-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.

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