Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei
Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei
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DOI：
10.1088/1475-7516/2014/11/021
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发表时间：
2014-07
影响因子：
6.4
通讯作者：
M. D. Mauro;A. Cuoco;F. Donato;J. Siegal-Gaskins
中科院分区：
文献类型：
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作者：
M. D. Mauro;A. Cuoco;F. Donato;J. Siegal-Gaskins
射电活动星系核（AGN）被认为对各向同性γ射线背景（IGRB）的强度和各向异性都有重要贡献。反过来，IGRB的测量属性可用于约束提议的贡献源类的特征。我们考虑了射电强AGN的各个亚类，包括低、中、高同步辐射峰值的BL Lacertae天体、平谱射电类星体和不对准的AGN。利用这些种群的γ射线亮度函数的更新模型，我们评估了每个源类对IGRB的强度和各向异性的能量依赖贡献。通过费米大面积望远镜（LAT）的测量，我们发现集体无线电大AGN可以解释IGRB的全部强度和各向异性。未对准的AGN提供了测量强度的大部分，但对各向异性的贡献可以忽略不计，而高同步加速器峰值的BL Lacertae物体对各向异性的贡献占主导地位。在Fermi-LAT和Cherenkov望远镜阵列即将进行的测量中，我们预测了在更广泛的能量范围内的各向异性，这将有助于未来的观测。
Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic γ-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the γ-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations.