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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

ABSTRACT  We study the impact of gas motions on the polarization of bright X‐ray emission lines from the hot intercluster medium. The polarization naturally arises from resonant scattering of emission lines owing to a quadrupole component in the radiation field produced by a centrally peaked gas density distribution. If differential gas motions are present, then a photon emitted in one region of the cluster will be scattered in another region only if their relative velocities are small enough and the Doppler shift of the photon energy does not exceed the linewidth. This affects both the degree and the direction of polarization. The changes in the polarization signal are in particular sensitive to the gas motions  perpendicular  to the line of sight.  We calculate the expected degree of polarization for several patterns of gas motions, including a slow inflow expected in a simple cooling flow model and a fast outflow in an expanding spherical shock wave. In both cases, the effect of non‐zero gas velocities is found to be minor. We also calculate the polarization signal for a set of clusters, taken from large‐scale structure simulations and evaluate the impact of the gas bulk motions on the polarization signal.  We argue that the expected degree of polarization is within reach of the next generation of space X‐ray polarimeters.

Polarization of X‐ray lines from galaxy clusters and elliptical galaxies – a way to measure the tangential component of gas velocity