Non-thermal cosmic backgrounds from blazars: the contribution to the CMB, X-ray and γ-ray backgrounds
Non-thermal cosmic backgrounds from blazars: the contribution to the CMB, X-ray and γ-ray backgrounds
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耀变体的非热宇宙背景：对 CMB、X 射线和 γ 射线背景的贡献
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
C. Pittori
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作者：
P. Giommi;S. Colafrancesco;E. Cavazzuti;M. Perri;C. Pittori
我们提出了一个新的评估的贡献耀变体人口的河外背景辐射的电磁频谱。我们的计算依赖于深耀变体无线电计数，我们已经通过结合几个无线电和多频调查得出。我们发现，耀变体辐射在宇宙时间上的积分产生了相当大的宽带非热宇宙背景，在电磁波谱的某些部分主导了河外亮度，
我们确认耀变体是宇宙微波背景（CMB）的主要离散贡献者，其中我们估计它们的积分发射在50-250 GHz频率范围内引起5-50 μ K的表观温度升高。CMB原始波动谱在多极$l约300{-}600$，在一个完全随机的源分布的情况下，或在较低的$l $值，如果空间聚类是存在的污染。我们估计，超过10万个耀变体将在即将到来的普朗克CMB各向异性使命的地图上产生显著的信号。由于微波和X射线通量之间的紧密相关性，这些源被期望是在软X射线带中具有大于几个10 - 15 erg cm-2 s-1的通量的X射线发射器。 因此，在当前和不久的将来的CMB各向异性地图的前景源的一个很大的部分可以被识别和删除使用多频率的方法，提供了一个足够深的全天空X射线调查将成为在不久的将来。我们进一步表明耀变体是所有高能量河外背景的主要组成部分。
它们的贡献在X射线频率下预计为11-12%，在0.5-50 MeV波段可能为100%。在较高能量（$E > 100~$MeV）下，利用EGRET探测源的SED将其积分微波通量外推到γ射线波段得到的Blazar集体辐射估计值大大高估了河外背景，这意味着Blazar不仅在γ射线天空中占主导地位，而且它们在这些频率下的平均占空比一定很低。最后，我们发现，耀变体的HBL型可能会产生大量的磁通在TeV的能量。
We present a new assessment of the contribution of the blazar population to the extragalactic background radiation across the electromagnetic spectrum. Our calculations rely on deep blazar radio counts that we have derived by combining several radio and multi-frequency surveys. We show that blazar emission integrated over cosmic time gives rise to a considerable broad-band non-thermal cosmic background that in some parts of the electromagnetic spectrum dominates the extragalactic brightness.
We confirm that blazars are the main discrete contributors to the Cosmic Microwave Background (CMB), where we estimate that their integrated emission causes an apparent temperature increase of 5-50 μ K in the frequency range 50-250 GHz. The CMB primordial fluctuation spectrum is contaminated starting at multipole $l approx 300{-}600$, in the case of a completely random source distribution, or at lower $l $ values if spatial clustering is present. We estimate that well over one hundred-thousand blazars will produce a significant signal in the maps of the upcoming Planck CMB anisotropy mission. Because of a tight correlation between the microwave and the X-ray flux, these sources are expected to be X-ray emitters with flux larger than a few 10 -15 erg cm -2 s -1 in the soft X-ray band. A large fraction of the foreground sources in current and near-future CMB anisotropy maps could therefore be identified and removed using a multi-frequency approach, provided that a sufficiently deep all-sky X-ray survey will become available in the near future.
We show further that blazars are a major constituent of all high energy extragalactic backgrounds. Their contribution is expected to be 11-12% at X-ray frequencies and possibly 100% in the ∼ 0.5-50 MeV band. At higher energies ($E > 100~$MeV) the estimated blazar collective emission, obtained by extrapolating their integrated micro-wave flux to the γ -ray band using the SED of EGRET detected sources, overestimates the extragalactic background by a large factor, thus implying that not only blazars dominate the γ -ray sky but also that their average duty cycle at these frequencies must be rather low. Finally, we find that blazars of the HBL type may produce a significant amount of flux at TeV energies.