Radiative efficiency is an important physical parameter that describes the fraction of accretion material converted to radiative energy for accretion onto massive black holes （MBHs）. With the simplest Sottan argumen...Radiative efficiency is an important physical parameter that describes the fraction of accretion material converted to radiative energy for accretion onto massive black holes （MBHs）. With the simplest Sottan argument, the radiative efficiency of MBHs can be estimated by matching the mass density of MBHs in the local universe to the accreted mass density by MBHs during AGN/QSO phases. In this paper, we estimate the local MBH mass density through a combination of various determinations of the correlations between the masses of MBHs and the properties of MBH host galaxies, with the distribution functions of those galaxy properties. We also estimate the total energy density radiated by AGNs and QSOs by using various AGN/QSO X-ray luminosity functions in the literature. We then obtain several hundred estimates of the mean radiative efficiency of AGNs/QSOs. Under the assumption that those estimates are independent of each other and free of systematic effects, we apply the median statistics as described by Gott et al. and find the mean radiative efficiency of AGNs/QSOs is ε = 0.105＋0.006- 0.008, which is consistent with the canonical value -0.1. Considering that about 20% Compton-thick objects may be missed from current available X-ray surveys, the true mean radiative efficiency may be actually -0.12.展开更多
费米伽玛射线空间大区域望远镜(Large Area Telescope,LAT),以前称为Gamma ray Large Area Space Telescope(GLAST))比Energetic Gamma Ray Experiment Telescope(EGRET)提高了观测精度,在服役的初始几个月中已经检测到一些具有快速光...费米伽玛射线空间大区域望远镜(Large Area Telescope,LAT),以前称为Gamma ray Large Area Space Telescope(GLAST))比Energetic Gamma Ray Experiment Telescope(EGRET)提高了观测精度,在服役的初始几个月中已经检测到一些具有快速光变伽玛射线源.用LAT观测结果并结合EGRET观测到的伽玛噪Blazar天体的变化时标和伽玛射线光度来估计天体的中心黑洞质量.我们发现中心黑洞质量下限范围为(0.3～24)×107M⊙,并将此结果与其他作者的研究结果进行了比较,发现结果是一致的.我们也给出了18个有已知超光速伽玛噪Blazar天体的洛伦兹因子(Γ)和视角(θ).展开更多
Dear Editors,Active Galactic Nuclei（AGNs）are very effective tools to study the environment both intrinsic to the central black holes of galaxies[1],or absorbing gas distributed along the sight lines.Recently,numerou...Dear Editors,Active Galactic Nuclei（AGNs）are very effective tools to study the environment both intrinsic to the central black holes of galaxies[1],or absorbing gas distributed along the sight lines.Recently,numerous highly ionized,local（z=0）metal absorption lines were detected in the X-ray spectra of background AGNs[2],providing an important method in probing hot gas and its content in and around our Galaxy.展开更多
基金the National Key Program for Science and Technology Research and Development(Grant No.2016YFA0400704)the National Natural Science Foundation of China(Grant Nos.11373031,and11390372)the Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB 23040100)
文摘Radiative efficiency is an important physical parameter that describes the fraction of accretion material converted to radiative energy for accretion onto massive black holes （MBHs）. With the simplest Sottan argument, the radiative efficiency of MBHs can be estimated by matching the mass density of MBHs in the local universe to the accreted mass density by MBHs during AGN/QSO phases. In this paper, we estimate the local MBH mass density through a combination of various determinations of the correlations between the masses of MBHs and the properties of MBH host galaxies, with the distribution functions of those galaxy properties. We also estimate the total energy density radiated by AGNs and QSOs by using various AGN/QSO X-ray luminosity functions in the literature. We then obtain several hundred estimates of the mean radiative efficiency of AGNs/QSOs. Under the assumption that those estimates are independent of each other and free of systematic effects, we apply the median statistics as described by Gott et al. and find the mean radiative efficiency of AGNs/QSOs is ε = 0.105＋0.006- 0.008, which is consistent with the canonical value -0.1. Considering that about 20% Compton-thick objects may be missed from current available X-ray surveys, the true mean radiative efficiency may be actually -0.12.
文摘费米伽玛射线空间大区域望远镜(Large Area Telescope,LAT),以前称为Gamma ray Large Area Space Telescope(GLAST))比Energetic Gamma Ray Experiment Telescope(EGRET)提高了观测精度,在服役的初始几个月中已经检测到一些具有快速光变伽玛射线源.用LAT观测结果并结合EGRET观测到的伽玛噪Blazar天体的变化时标和伽玛射线光度来估计天体的中心黑洞质量.我们发现中心黑洞质量下限范围为(0.3～24)×107M⊙,并将此结果与其他作者的研究结果进行了比较,发现结果是一致的.我们也给出了18个有已知超光速伽玛噪Blazar天体的洛伦兹因子(Γ)和视角(θ).
基金supported by the National Natural Science Foundation of China (Grant Nos. 11273021 and 11525312)by Strategic Priority Program "The Emergence of Cosmological Structures" of the China Academy of Sciences (Grant No. XDB09000000)
文摘Dear Editors,Active Galactic Nuclei（AGNs）are very effective tools to study the environment both intrinsic to the central black holes of galaxies[1],or absorbing gas distributed along the sight lines.Recently,numerous highly ionized,local（z=0）metal absorption lines were detected in the X-ray spectra of background AGNs[2],providing an important method in probing hot gas and its content in and around our Galaxy.
