The XMM Cluster Survey: new evidence for the 3.5 keV feature in clusters is inconsistent with a dark matter origin. (arXiv:2006.13955v1 [astro-ph.CO])

The XMM Cluster Survey: new evidence for the 3.5 keV feature in clusters is inconsistent with a dark matter origin. (arXiv:2006.13955v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bhargava_S/0/1/0/all/0/1">S. Bhargava</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Giles_P/0/1/0/all/0/1">P. A. Giles</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Romer_A/0/1/0/all/0/1">A. K. Romer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jeltema_T/0/1/0/all/0/1">T. Jeltema</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mayers_J/0/1/0/all/0/1">J. Mayers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bermeo_A/0/1/0/all/0/1">A. Bermeo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hilton_M/0/1/0/all/0/1">M. Hilton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wilkinson_R/0/1/0/all/0/1">R. Wilkinson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vergara_C/0/1/0/all/0/1">C. Vergara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Collins_C/0/1/0/all/0/1">C. A. Collins</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Manolopoulou_M/0/1/0/all/0/1">M. Manolopoulou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rooney_P/0/1/0/all/0/1">P. J. Rooney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosborough_S/0/1/0/all/0/1">S. Rosborough</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sabirli_K/0/1/0/all/0/1">K. Sabirli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stott_J/0/1/0/all/0/1">J. P. Stott</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Swann_E/0/1/0/all/0/1">E. Swann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Viana_P/0/1/0/all/0/1">P. T. P. Viana</a>

There have been several reports of a detection of an unexplained excess of
X-ray emission at $simeq$ 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 $simeq$ 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
$simeq$ 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 ($T_{rm X}$) bins to search for an increase in $simeq$ 3.5 keV
flux excess with $T_{rm X}$ – a reliable tracer of halo mass. However, we do
not find evidence of a significant excess in flux at $simeq$ 3.5 keV in any
$T_{rm X}$ bins. To maximise sensitivity to a potentially weak dark matter
decay feature at $simeq$ 3.5 keV, we jointly fit 114 clusters. Again, no
significant excess is found at $simeq$ 3.5 keV. We estimate the upper limit of
an undetected emission line at $simeq$ 3.5 keV to be $2.41 times 10^{-6}$
photons cm$^{-2}$ s$^{-1}$, corresponding to a mixing angle of
$sin^2(2theta)=4.4 times 10^{-11}$, lower than previous estimates from
cluster studies. We conclude that a flux excess at $simeq$ 3.5 keV is not a
ubiquitous feature in clusters and therefore unlikely to originate from sterile
neutrino dark matter decay.

There have been several reports of a detection of an unexplained excess of
X-ray emission at $simeq$ 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 $simeq$ 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
$simeq$ 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 ($T_{rm X}$) bins to search for an increase in $simeq$ 3.5 keV
flux excess with $T_{rm X}$ – a reliable tracer of halo mass. However, we do
not find evidence of a significant excess in flux at $simeq$ 3.5 keV in any
$T_{rm X}$ bins. To maximise sensitivity to a potentially weak dark matter
decay feature at $simeq$ 3.5 keV, we jointly fit 114 clusters. Again, no
significant excess is found at $simeq$ 3.5 keV. We estimate the upper limit of
an undetected emission line at $simeq$ 3.5 keV to be $2.41 times 10^{-6}$
photons cm$^{-2}$ s$^{-1}$, corresponding to a mixing angle of
$sin^2(2theta)=4.4 times 10^{-11}$, lower than previous estimates from
cluster studies. We conclude that a flux excess at $simeq$ 3.5 keV is not a
ubiquitous feature in clusters and therefore unlikely to originate from sterile
neutrino dark matter decay.

http://arxiv.org/icons/sfx.gif