The X-Ray Line Feature At 3.5 Kev In Galaxy Cluster Spectra

Abstract

Recent work by Bulbul et al. and Boyarsky et al. has suggested that a line feature at approx. 3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate. This identification has been criticized by Jeltema and Profumo on the grounds that model spectra suggest that atomic transitions in helium-like potassium (K XVIII) and chlorine (Cl XVI) are more likely to be the emitters. Here it is pointed out that the K XVIII lines have been observed in numerous solar flare spectra at high spectral resolution with the RESIK crystal spectrometer and also appear in Chandra HETG spectra of the coronally active star sigma Gem. In addition, the solar flare spectra at least indicate a mean coronal potassium abundance which is a factor of between 9 and 11 higher than the solar photospheric abundance. This fact, together with the low statistical quality of the XMM-Newton spectra, completely accounts for the approx. 3.5 keV feature and there is therefore no need to invoke a sterile neutrino interpretation of the observed line feature at 3.5 keV.

Accepted for publication, Astrophysical Journal. 3 figures

References in corpus (3)

• Discovery of a 3.5 keV line in the Galactic Center and a Critical Look at the Origin of the Line Across Astronomical Targets
• Solar Flare Element Abundances from the Solar Assembly for X-rays (SAX) on MESSENGER
• RESIK Solar X-ray flare element abundances on a non-isothermal assumption

Cited by in corpus (15)

• Sterile Neutrino Dark Matter
• A White Paper on keV Sterile Neutrino Dark Matter
• The Present and Future Status of Heavy Neutral Leptons
• Astrophysical constraints on resonantly produced sterile neutrino dark matter
• Deep XMM Observations of Draco rule out at the 99% Confidence Level a Dark Matter Decay Origin for the 3.5 keV Line
• Dodelson-Widrow Production of Sterile Neutrino Dark Matter with Non-Trivial Initial Abundance
• Fermionic dark matter via UV and IR freeze-in and its possible X-ray signature
• Observation of the new emission line at ~3.5 keV in X-ray spectra of galaxies and galaxy clusters
• The Doppler effect on indirect detection of dark matter using dark matter only simulations
• Dark Matter Inelastic Up-Scattering with the Interstellar Plasma: An Exciting New Source of X-Ray Lines, including at 3.5 keV
• Checking Potassium origin of new emission line at 3.5 keV with K XIX line complex at 3.7 keV
• Polarization of photons emitted by decaying dark matter
• An alternative interpretation for cosmic ray peaks
• Dwarf Galaxy $\gamma$-excess and 3.55 keV X-ray Line In A Nonthermal Dark Matter Model
• Can decaying sterile neutrinos account for all dark matter?