Do the broad emission line clouds see the same continuum that we see?

被引:85
作者
Korista, K [1 ]
Ferland, G [1 ]
Baldwin, J [1 ]
机构
[1] ASSOC UNIV RES ASTRON INC,CERRO TOLOLO INTER AMER OBSERV,LA SERENA,CHILE
关键词
line; formation; quasars; emission lines; ultraviolet; galaxies;
D O I
10.1086/304659
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Recent observations of quasars, Mrk 335 and the HST quasar composite spectrum, have indicated that many quasars have remarkably soft ionizing continua (f(v) proportional to v(-2), 13.6-100 eV). We point out that the number of photons with hv > 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 lambda 1549 and O VI lambda 1034 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 W-EUV SED is double peaked, with the second peaking near 54 eV, its Wien tail being the observed soft X-ray excess.
引用
收藏
页码:555 / 559
页数:5
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