EMSS样品中活动星系核的X射线流量计数

X-RAY COUNTS OF ACTIVE GALACTIC NUCLEI IN EINSTEIN EXTENDED MEDIUM SENSITIVITY SURVEY

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5×10^(14) ergem^(-2) s^(-1) X流量限制下AGNS对X射线背景贡献为13.5%。

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^(-14)to 1×10^(-11) erg cm^(-2)s^(-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^(-2)s^(-1). The contribution of AGNs to CXB increases as limiting flux decreases.