EUVE Science Highlights - May 31, 1998

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EUVE discovered diffuse EUV emission from clusters of galaxies. The origin of this emission has been controversial. An interpretation of this emission in terms of a lower temperature thermal gas component is unlikely considering its short cooling time. Inverse Compton scattering of low energy cosmic ray electrons against the 3oK cosmic microwave background has been suggested to explain the EUV excess of clusters of galaxies. The integrated fluxes seem to be consistent with the observed synchrotron emission of the relativistic electrons and the magnetic field in the intra-cluster medium. Bowyer and Berghöfer (accepted for publication in ApJ, 1998) investigated the spatial distribution of EUV excess of the Coma cluster and demonstrated that the distribution of EUV emission is elongated in the east-west direction (see the attached figure) as observed in the Radio maps. However, the EUV emission of Coma cannot be produced by an extrapolation to lower energies of the observed synchrotron radio emitting electrons, and an additional component of low energy cosmic ray electrons is required. More details are available in the preprint by Bowyer and Berghöfer at ftp://sag-ftp.ssl.berkeley.edu/pub/coma.