High-energy Emission Component, Population, and Contribution to the Extragalactic Gamma-Ray Background of Gamma-Ray-emitting Radio Galaxies
High-energy Emission Component, Population, and Contribution to the Extragalactic Gamma-Ray Background of Gamma-Ray-emitting Radio Galaxies
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DOI：
10.3847/1538-4357/ac6acb
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发表时间：
2022-04
期刊：
影响因子：
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通讯作者：
Y. Fukazawa;H. Matake;T. Kayanoki;Y. Inoue;J. Finke
中科院分区：
文献类型：
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作者：
Y. Fukazawa;H. Matake;T. Kayanoki;Y. Inoue;J. Finke
本文系统地研究了费米大天区望远镜探测到的61个射电星系的X射线-GeV γ射线谱。在射电星系的高能光谱分量中，我们发现了与耀变体相似的峰值频率与峰值光度之间的关系。利用这个样本，我们还构造了一个伽玛射线射电星系的伽玛射线光度函数（GLF）。我们发现类耀变体的GLF形状可以再现它们的红移和光度分布，但log N-log S关系更倾向于具有更多低z射电星系的模型。利用我们最新的GLF，射电星系对河外γ射线背景的贡献为1%-10%。我们进一步研究了伽马射线射电星系的性质。与射电或X射线通量有限的射电星系样本相比，伽马射线选择的样本往往缺乏像FR II射电星系这样的高射电功率星系。我们还发现，只有10%的射电星系是GeV的伽马射线响亮。射电星系可能有助于宇宙兆电子伏的伽玛射线背景相媲美耀变体，如果伽玛射线安静的射电星系有X射线到伽玛射线的光谱，如岑A，与一个小的伽玛射线到X射线的流量比。
In this study, we systematically studied the X-ray to GeV gamma-ray spectra of 61 Fermi Large Area Telescope detected radio galaxies. We found an anticorrelation between peak frequency and peak luminosity in the high-energy spectral component of radio galaxies, similar to blazars. With this sample, we also constructed a gamma-ray luminosity function (GLF) of gamma-ray-loud radio galaxies. We found that blazar-like GLF shapes can reproduce their redshift and luminosity distribution, but the log N–log S relation prefers models with more low-z radio galaxies. Utilizing our latest GLF, the contribution of radio galaxies to the extragalactic gamma-ray background is found to be 1%–10%. We further investigated the nature of gamma-ray-loud radio galaxies. Compared to radio or X-ray flux-limited radio galaxy samples, the gamma-ray-selected sample tends to lack high radio power galaxies like FR II radio galaxies. We also found that only ∼10% of radio galaxies are GeV gamma-ray loud. Radio galaxies may contribute to the cosmic MeV gamma-ray background comparable to blazars if gamma-ray-quiet radio galaxies have X-ray to gamma-ray spectra like Cen A, with a small gamma-ray-to-X-ray flux ratio.