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

We report on NuSTAR and Swift observations of a soft state of the neutronstar low-mass X-ray binary GS 1826-24, commonly known as the "clocked" burster.The transition to the soft state was recorded in 2014 June through an increaseof the 2-20 keV source intensity measured by MAXI, simultaneous with a decreaseof the 15-50 keV intensity measured by Swift/BAT. The episode lastedapproximately two months, after which the source returned to its usual hardstate. We analyze the broad-band spectrum measured by Swift/XRT and NuSTAR, andestimate the accretion rate during the soft episode to be about 13% ofEddington, within the range of previous observations. However, the best fitspectral model, adopting the double Comptonization used previously, exhibitssignificantly softer components. We detect seven type-I X-ray bursts, allsignificantly weaker (and with shorter rise and decay times) than observedpreviously. The burst profiles and recurrence times vary significantly, rulingout the regular bursts that are typical for this source. One burst exhibitedphotospheric radius expansion, and we estimate the source distance at about(5.7 / xi_b^1/2) kpc, where xi_b parameterizes the possible anisotropy of theburst emission. Interpreting the soft state as a transition from an opticallythin inner flow to an optically thick flow passing through a boundary layer, asis commonly observed in similar systems, is contradicted by the lower opticaldepth measured for the double Comptonization model we find for this soft state.The effect of a change in disk geometry on the burst behavior remains unclear.

A Soft X-Ray Spectral Episode for the Clocked Burster, GS 1826-24 as Measured by Swift and NuSTAR