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

Cygnus X-1, the well-known accreting black hole system, exhibits severalobservational features hinting at an intricate interplay between the accretiondisk, its atmosphere known as the corona and the putative relativistic jet. Ithas been extensively studied using all available observational methods,including using the newly available technique of sensitive X-ray polarimetry.X-ray polarization characteristics are distinct for coronal and jet emissions.The low X-ray polarization measured below $\sim$100 keV is understood asarising from the corona. In contrast, the high polarization measurementsreported above $\sim$400 keV required a separate jet-dominated spectralcomponent, which spectroscopy does not demonstrate conclusively. Here we reportprecise polarization measurements in the 100-380 keV region made during threedifferent sub-classes of spectral states of the source using the CZTIinstrument onboard {\em AstroSat}. A high polarization (23$\pm$4 \%) is foundmainly in the Intermediate Hard State of the source, and the energy-resolvedmeasurements smoothly connect the coronal and the jet regimes. When highpolarization is observed, the simultaneous spectral data hints at a separatepower law component above 100 keV. We examine the possible sources of thisenergy-dependent high polarization in Cygnus X-1.

High hard X-ray polarization in Cygnus X-1 confined to the intermediate hard state: evidence for a variable jet component