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[10.08] Re-observing Several EUV Excess Clusters with in Situ Background Measurements by Pointings at Small Offset

J.P.D. Mittaz (MSSL), R. Lieu, M. Bonamente (UAH)

EUV emission from clusters of galaxies is observed to be well in excess of that expected from the hot intracluster medium. The phenomenon is likely to be one of substantial impact on our understanding of cluster formation and evolution, irrespective of its correct final interpretation. Here we present EUVE re-observations of Virgo, A1795 and A2199 which feature measuremclear signatures of this Virgo EUV trend in 1/4 keV soft X-rays. We discuss the consequences of the latest findings on both the thermal and non-thermal scenarios for the soft component. ents of the in situ background by pointing at small offsets from the targets. The original results were reproduced amidst these additional `control' data and more scrutinizing analysis methods; in particular the possible association of the detected cluster signals with background effects is categorically excluded. A rising radial trend in the relative importance of the EUV excess in Virgo is established, which now renders the three clusters alike. A more careful re-visit to the ROSAT PSPC data also revealed clear signatures of this Virgo EUV trend in 1/4 keV soft X-rays. We discuss the consequences of the latest findings on both the thermal and non-thermal scenarios for the soft component.