Recent observations of quasars, Mrk 335 and the HST quasar composite spectrum, have indicated that many quasars have remarkably soft ionizing continua (f ~ ν-2, 13.6-100 eV). We point out that the number of photons with hν > 54.4 eV is insufficient to create the observed strengths of the He II emission lines. While the numbers of photons which energize C IV λ1549 and O VI λ1034 are sufficient, even the most efficiently emitting clouds for these two lines must each cover at least 20%-40% of the source. If the typical quasar ionizing continuum is indeed this soft, then we must conclude that the broad emission line clouds must see a very different (harder) continuum than we see. The other viable possibility is that the UV-EUV SED is double peaked, with the second peaking near 54 eV, its Wien tail being the observed soft X-ray excess.

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Published in The Astrophysical Journal, v. 487, no. 2, p. 555-559.

© 1997. The American Astronomical Society. All rights reserved. Printed in the U.S.A.

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