The Proximity Effect Of Lyα Forest In High-resolution Spectra Of Quasars

Previous work about Ly a Forest was on the basis of low- or moderate-resolution data, where lines blending is severe. So more research with high-resolution data is necessary. We form a Ly a line sample from spectra of 19 QSOs in the literature. In this analysis , we demonstrate that a proximity effect is present in thedata; i.e., there exists a significant deficit of lines at zabs=zem, within 4h-1 Mpc ofthe QSO emission redshift. And the deficit depends on the rest equivalent width of the lines, with weak lines showing a relatively weaker effect. The simplest explanation for this effect is enhanced ionization of H I in the vicinity of the QSO by ultraviolet photons from the QSO itself presented by Bajtlik, Duncan, & Ostriker(BDO). If the "Photoionization Model" is correct ,it permits an estimate of the mean intensity of the extragalactic background radiation at the Lyman limit. If this background is assumed to be constant over the redshift range which can be exploredat present, then the best-fit values for J(vo) are: (1) for W>0.32A,logJ(vo)=-21.20; (2) for W>0.16A , logJ(vo)=-21.63; (3)for0.16A