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

In late 2008, the quasi‐persistent neutron star X‐ray transient and eclipsing binary EXO  0748−676  started a transition from outburst to quiescence, after it actively accreted for more than 24 yr. In a previous work, we discussed  Chandra  and  Swift  observations obtained during the first 5 months of this transition. Here, we report on further X‐ray observations of EXO  0748−676 , extending the quiescent monitoring to 1.6 yr.  Chandra  and  XMM–Newton  data reveal quiescent X‐ray spectra composed of a soft, thermal component that is well fitted by a neutron star atmosphere model. An additional hard power‐law tail is detected that changes non‐monotonically over time, contributing between 4 and 20 per cent to the total unabsorbed 0.5–10 keV flux. The combined set of  Chandra ,  XMM–Newton  and  Swift  data reveals that the thermal bolometric luminosity fades from  ∼ 1 × 10 34   to  6 × 10 33  (D/7.4 kpc) 2   erg s  −1  , whereas the inferred neutron star effective temperature decreases from ∼124 to 109 eV. We interpret the observed decay as cooling of the neutron star crust and show that the fractional quiescent temperature change of EXO  0748−676  is markedly smaller than observed for three other neutron star X‐ray binaries that underwent prolonged accretion outbursts.

Further X‐ray observations of EXO 0748−676 in quiescence: evidence for a cooling neutron star crust