7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS
Journal
ASTRONOMY & ASTROPHYSICS
Date Issued
2016
Author(s)
DOI
10.1051/0004-6361/201527977
Abstract
Context. Recently an unidentified emission line at 3.55 keV has been detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV 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 7.1 keV 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 100 ks of combined exposure. The resulting high signal-to-noise spectra are used to constrain the flux of an unidentified line emission at 3.55 keV in the individual spectra and a merged spectrum of all clusters.
Results: We obtained very detailed spectra around the 3.55 keV range and limits on an unidentified emission line. Assuming all DM were made of 7.1 keV sterile neutrinos, the upper limits on the mixing angle are sin2(2Θ) < 10.1×10^-11 from ACIS-I and < 40.3×10^-11 from ACIS-S data at 99.7 per cent confidence level.
Conclusions: We do not find evidence for an unidentified emission line at 3.55 keV. The sample extends the list of objects searched for an emission line at 3.55 keV 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.
Volume
592
Start page
A112
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
29290-aa27977-15_P01.pdf
Description
Miur
Size
7.13 MB
Format
Adobe PDF
Checksum (MD5)
2699255d7cd4dccb27a794e68ca24727
Loading...
Name
29290-aa27977-15_P02.pdf
Description
Miur
Size
7.4 MB
Format
Adobe PDF
Checksum (MD5)
501ce2ff70098b2531a1c9503afc46da