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

Recently an unidentified emission line at 3.55 keV has been detected in X-rayspectra of clusters of galaxies. The line has been discussed as a possibledecay signature of 7.1 keV sterile neutrinos, which have been proposed as adark matter candidate. We aim at putting constraints on the proposed lineemission in a large sample of Chandra-observed clusters and obtain limits onthe mixing-angle in a 7.1 keV sterile neutrino dark matter scenario. For asample of 33 high-mass clusters of galaxies we merge all observations from theChandra data archive. Each cluster has more than 100 ks of combined exposure.The resulting high signal-to-noise spectra are used to constrain the flux of anunidentified line emission at 3.55 keV in the individual spectra and a mergedspectrum of all clusters. We obtained very detailed spectra around the 3.55 keVrange and limits on an unidentified emission line. Assuming all dark matterwere made of 7.1 keV sterile neutrinos the upper limits on the mixing angle are$\rm{sin^2(2\Theta)}$ $\rm{<10.1\times10^{-11}}$ from ACIS-I, and$\rm{<40.3\times10^{-11}}$ from ACIS-S data at 99.7 per cent confidence level.We do not find evidence for an unidentified emission line at 3.55 keV. Thesample extends the list of objects searched for an emission line at 3.55 keVand will help to identify the best targets for future studies of the potentialdark matter decay line with upcoming X-ray observatories like Hitomi (Astro-H),eROSITA, and Athena.

7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS