|COOKIES: By using this website you agree that we can place Google Analytics Cookies on your device for performance monitoring.|
The Cluster Soft Excess, Dark Radiation and a 0.1-1 keV Cosmic Axion Background
If you have a question about this talk, please contact mustafa.a.amin.
Since 1996 soft excess emission above thermal bremsstrahlung from the intracluster medium has been observed from galaxy clusters in extreme ultraviolet and soft X-ray frequencies. We review proposed astrophysical explanations, and the difficulties they face in the light of cluster magnetic field measurements and null observations of clusters in gamma rays. String theory moduli that decay at t ~ 10-6 s generally have non-zero branching ratios to axion-like particles. These freestream to the present day and currently constitute a dark radiation Cosmic Axion Background at 0.1 – 1 keV energies. These axions can convert into photons in cluster magnetic fields, and allowed particle physics parameters can easily generate the required excess luminosity of approximately 1043 erg s-1. For the case of Coma, we use a detailed model of the Coma magnetic field to calculate the axion conversion probabilities and to study the resulting excess morphology.
This talk is part of the Cosmology lunch series.
This talk is included in these lists:
Note that ex-directory lists are not shown.
Other listsNeuropsychiatry discussion group Computer Laboratory talks Sir Andrew Motion Visits Cambridge in War Poets Event
Other talks2017 Annual WiSETI Lecture: A Life in Climate Science Energy in a Post-Brexit UK Braids, Cosimplicial Identities, Spreadability, Subfactors Behavioural Susceptibility to the 'obesogenc environment': gene-environment interactions in the obesity epidemic The Anthropocene seen by the Anopheles: fighting malarial mosquitoes with chemicals in modern China, 1910s–1960s Interventions in Accelerated Aging