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EXTRA-SOFT X-RAY EXCESS OF QUASARS
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作者 周又元 晏明 +1 位作者 程富华 苏暘 《Science China Mathematics》 SCIE 1990年第6期720-728,共9页
In a quasar sample with strong soft X-ray emission, we construct a sample of extra-soft X-ray excess quasars in virtue of the relation between the hydrogen column density, NH (IPC), determined by Einstein IPC, and NH ... In a quasar sample with strong soft X-ray emission, we construct a sample of extra-soft X-ray excess quasars in virtue of the relation between the hydrogen column density, NH (IPC), determined by Einstein IPC, and NH (21cm), determined by Galactic 21cm line. The X-ray spectral index a*E in the energy interval 0.3keV<E<0.5keV is calculated. a*E is obviously larger than the spectral index αE in 0.5keV<E<3.5keV, showing that 0.3-0.5keV is just the rapidly decreasing part of the right side of big bump from UV to soft X-ray.These results will help establish the composite model for this kind of big bump. 展开更多
关键词 extra-soft X-RAY EXCESS spectral index optieal-x-ray BIG BUMP quasars.
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