EUV EMISSION FROM NORMAL GALAXIES

Using data from the ROSAT Wide Field Camera all-sky survey, we have es tablished upper limits to the extreme-ultraviolet (EUV) flux from a sa mple of 30 bright, nearby, non-active spiral galaxies. These galaxies were chosen to be those most likely to be detected in the EW on the ba sis of (i) low interstellar absorption within our own Galaxy, (ii) bri ghtness in other wavebands, (iii) high star formation activity, and (i v) proximity. The derived EUV upper limits are restrictive, and establ ish that the EUV flux escaping from galaxies does not contribute a maj or component of their bolometric luminosity, and in particular that it is very unlikely to be the sink for the energy injected into the inte rstellar medium by supernova explosions, as had been suggested followi ng the failure to detect this power in the X-ray band.