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 studied the prominent bow shock in the merging galaxy cluster A520 using adeep Chandra X-ray observation and archival VLA radio data. This shock is auseful diagnostic tool, owing to its clear geometry and relatively high Machnumber. At the "nose" of the shock, we measure a Mach number of$M=2.4_{-0.2}^{+0.4}$. The shock becomes oblique away from the merger axis,with the Mach number falling to $\simeq$1.6 around 30$^{\circ}$ from the nose.The electron temperature immediately behind the shock nose is consistent withthat from the Rankine-Hugoniot adiabat, and is higher (at a 95% confidence)than expected for adiabatic compression of electrons followed by Coulombelectron-proton equilibration, indicating the presence of equilibrationmechanisms faster than Coulomb collisions. This is similar to an earlierfinding for the Bullet cluster. We also combined four archival VLA datasets toobtain a better image of the cluster's giant radio halo at 1.4 GHz. An abruptedge of the radio halo traces the shock front, and no emission is detected inthe pre-shock region. If the radio edge were due only to adiabatic compressionof relativistic electrons in pre-shock plasma, we would expect a pre-shockradio emission detectable in this radio dataset; however, an interferometricartifact dominates the uncertainty, so we cannot rule this model out. Otherinteresting features of the radio halo include a peak at the remnant of thecool core, suggesting that the core used to have a radio minihalo, and a peakmarking a possible region of high turbulence.

Bow shock in merging cluster A520: the edge of the radio halo and the electron-ion equilibration timescale