Astronomy and Astrophysics, volume 592A, 112-112 (2016/8-1)
7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS.
HOFMANN F., SANDERS J.S., NANDRA K., CLERC N. and GASPARI M.
Abstract (from CDS):
Context. Recently an unidentified emission line at 3.55keV has been detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1keV sterile neutrinos, which have been proposed as a dark matter (DM) candidate.
Aims. We aim to put constraints on the proposed line emission in a large sample of Chandra-observed clusters and obtain limits on the mixing angle in a 7.1keV sterile neutrino DM scenario.
Methods. For a sample of 33 high-mass clusters of galaxies, we merge all observations from the Chandra data archive. Each cluster has more than 100ks of combined exposure. The resulting high signal-to-noise spectra are used to constrain the flux of an unidentified line emission at 3.55keV in the individual spectra and a merged spectrum of all clusters.
Results. We obtained very detailed spectra around the 3.55keV range and limits on an unidentified emission line. Assuming all DM were made of 7.1keV sterile neutrinos, the upper limits on the mixing angle are sin2(2Θ)<10.1x10–11 from ACIS-I and <40.3x10–11 from ACIS-S data at 99.7 per cent confidence level.
Conclusions. We do not find evidence for an unidentified emission line at 3.55keV. The sample extends the list of objects searched for an emission line at 3.55keV and will help to identify the best targets for future studies of the potential DM decay line with upcoming X-ray observatories like Hitomi (Astro-H), eROSITA, and Athena.
© ESO, 2016
galaxies: clusters: general - X-rays: galaxies: clusters - dark matter
m0735, m1455 and pk0745 not identified (incomplete format).
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