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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present results from the first Suzaku observation of the high-mass X-raybinary 4U 1538-522. The broad-band spectral coverage of Suzaku allows for adetailed spectral analysis, characterizing the cyclotron resonance scatteringfeature at $23.0 \pm 0.4$ keV and the iron K$\alpha$ line at $6.426 \pm 0.008$keV, as well as placing limits on the strengths of the iron K$\beta$ line andthe iron K edge. We track the evolution of the spectral parameters both in timeand in luminosity, notably finding a significant positive correlation betweencyclotron line energy and luminosity. A dip and spike in the lightcurve isshown to be associated with an order-of-magnitude increase in column densityalong the line of sight, as well as significant variation in the underlyingcontinuum, implying the accretion of a overdense region of a clumpy stellarwind. We also present a phase-resolved analysis, with most spectral parametersof interest showing significant variation with phase. Notably, both thecyclotron line energy and the iron K$\alpha$ line intensity vary significantlywith phase, with the iron line intensity significantly out-of-phase with thepulse profile. We discuss the implications of these findings in the context ofrecent work in the areas of accretion column physics and cyclotron resonancescattering feature formation.

A Clumpy Stellar Wind and Luminosity-Dependent Cyclotron Line Revealed by The First Suzaku Observation of the High-Mass X-ray Binary 4U 1538-522