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The XMM Cluster Survey: new evidence for the 3.5-keV feature in clusters is inconsistent with a dark matter origin

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posted on 2023-06-07, 07:40 authored by Sunayana Bhargava, Paul GilesPaul Giles, Kathy RomerKathy Romer, T Jeltema, Julian Mayers, Alberto Bermeo, M Hilton, Reese WilkinsonReese Wilkinson, Carlos Fernando Vergara Cervantes, C A Collins, M Manolopoulou, Philip Rooney, S Rosborough, K Sabirli, J P Stott, E Swann, P T P Viana
There have been several reports of a detection of an unexplained excess of X-ray emission at ?3.5 keV in astrophysical systems. One interpretation of this excess is the decay of sterile neutrino dark matter. The most influential study to date analysed 73 clusters observed by the XMM–Newton satellite. We explore evidence for a ?3.5-keV excess in the XMM-PN spectra of 117 redMaPPer galaxy clusters (0.1 < z < 0.6). In our analysis of individual spectra, we identify three systems with an excess of flux at ?3.5 keV. In one case (XCS J0003.3+0204), this excess may result from a discrete emission line. None of these systems are the most dark matter dominated in our sample. We group the remaining 114 clusters into four temperature (TX) bins to search for an increase in ?3.5-keV flux excess with TX – a reliable tracer of halo mass. However, we do not find evidence of a significant excess in flux at ?3.5 keV in any TX bins. To maximize sensitivity to a potentially weak dark matter decay feature at ?3.5 keV, we jointly fit 114 clusters. Again, no significant excess is found at ?3.5 keV. We estimate the upper limit of an undetected emission line at ?3.5 keV to be 2.41 × 10-6 photons cm-2 s-1, corresponding to a mixing angle of sin?2(2?) = 4.4 × 10-11, lower than previous estimates from cluster studies. We conclude that a flux excess at ?3.5 keV is not a ubiquitous feature in clusters and therefore unlikely to originate from sterile neutrino dark matter decay.

History

Publication status

  • Published

File Version

  • Published version

Journal

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

Publisher

Oxford University Press

Issue

1

Volume

497

Page range

656-671

Pages

15.0

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2020-08-04

First Open Access (FOA) Date

2020-08-04

First Compliant Deposit (FCD) Date

2020-08-03

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