Simulating the Dark Matter Decay Signal from the Perseus Galaxy Cluster

Lovell, Mark R.; Iakubovskyi, Dmytro; Barnes, David; Bose, Sownak; Frenk, Carlos S.; Theuns, Tom; Hellwing, Wojciech A.

Abstract

the C-EAGLE simulations of galaxy clusters to predict the flux, width, and shape of a dark matter decay line, paying particular attention to the unexplained 3.55keV line detected in the spectra of some galaxies and clusters, and the upcoming XRISM X-ray observatory mission. We show that the line width in C-EAGLE clusters similar to Perseus is typically [600–800]km s-1, and therefore narrower than the amplitude of the velocity dispersion of galaxies in the cluster. Halos that are significantly disturbed can, however, exhibit galaxy velocity dispersions higher than 1000km s-1, and in this case will show a large difference between the line profiles of on- and offcenter observations. We show that the line profile is likely to be slightly asymmetric, but still well approximated by a Gaussian at the 10% level, and that the halo asymmetry can lead to fluxes that vary by a factor of two. In summary, we predict that, if the previously reported 3.55keV line detections do originate from dark matter decay, the XRISM mission will detect a line with a roughly Gaussian profile at a rest-frame energy of 3.55keV, with a width >600 km s-1and flux approximately in the range [4–9] ´ 10-8 counts s-1 cm-2.

Citation

Lovell, M. R., Iakubovskyi, D., Barnes, D., Bose, S., Frenk, C. S., Theuns, T., & Hellwing, W. A. (2019). Simulating the Dark Matter Decay Signal from the Perseus Galaxy Cluster. Astrophysical Journal Letters, 875(2), Article L24. https://doi.org/10.3847/2041-8213/ab13ac

• Journal Article Type: Article
• Acceptance Date: Mar 26, 2019
• Online Publication Date: Apr 19, 2019
• Publication Date: Apr 19, 2019
• Deposit Date: May 9, 2019
• Publicly Available Date: May 9, 2019
• Journal: Astrophysical Journal
• Print ISSN: 2041-8205
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 875
• Issue: 2
• Article Number: L24
• DOI: https://doi.org/10.3847/2041-8213/ab13ac