【摘要】 本文采用目前已知最大的活动星系核（AGNS）样本——扩展的中灵敏度巡天（EMSS）,得出了AGNS在0.3—3.5keV能段上,流量在1×10^-11与5×10^-14 ergem^-2 s^-1间的计数关系,其logN（>S）—logS图满足直线关系,斜率α=—1.59±0.06.并进一步计算了在5×10¹⁴ ergem^-2 s^-1 X流量限制下AGNS对X射线背景贡献为13.5%。更多还原

【Abstract】 Using Active Galactic Nuclei （AGNs） subsample, the largest one recently known, extracted from Einstein Extended Medium Sensitivity Survey Sample, we obtain the relation of AGN number density-limiting flux for fluxes from 5×10^-14to 1×10^-11 erg cm^-2s^-1 in 0.3—3.5 keV energy band. In diagram log N（>S） —logS the best fitting is linear with a slope of α=—1.59±0.06. This resuh shows the evolution of AGNs for X-ray properties, but it is not as strong as previous result α=—1.71±0.16 Judged from the sample scale and parameter precision, the new result is more reliable. We also estimate that 13.5% of X-ray background （C×B） comes from AGNs which are brighter than 5×10^-14 ergcm^-2s^-1. The contribution of AGNs to CXB increases as limiting flux decreases.更多还原