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arXiv 1906.07653astro-ph.HE
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高能gamma-ray观测河外背景光的归一化

Normalization of the extragalactic background light from high-energy gamma-ray observations

B. Biasuzzi, O. Hervet, D. A. Williams, J. Biteau

摘要:

河外背景光(EBL)在宇宙学中起着重要的作用,因为它可以追溯星系形成和演化的历史。这种从近紫外到远红外波长的漫射辐射可以与来自遥远来源(如活动星系核)的$γ$ -射线相互作用,并负责在其光谱中观察到的高能吸收。然而,探测活动星系核的$γ$射线谱的EBL并不是微不足道的,因为内部过程可以模仿它的效果。这样的过程通常被考虑在内禀光谱的曲率方面。因此,后者的参数化选择不当会严重影响EBL重建。在本文中,我们提出了一种统计方法,避免了先验假设的内在光谱曲率,并为每个源,选择最适合的模型在坚实的统计基础上。通过结合490个blazar的${\it Fermi}$ -LAT观测,我们确定了各种最先进的EBL模型的$γ$ -射线推断的EBL水平。我们讨论了从BL Lac和平坦谱射电类星体(FSRQ)的光谱中获得的EBL能级,以研究不同类型天体内部吸收的影响。我们通过重建四个红移范围内的EBL能级,从$γ$射线观测进一步审查了EBL演化的约束,直到$z\sim2.5$。在本文中实施的方法,仔细解决的问题的建模的固有发射的源,可以作为一个坚实的垫脚石的研究数百个高品质的光谱获得的下一代$γ$射线仪器。

英文摘要:

Extragalactic background light (EBL) plays an important role in cosmology since it traces the history of galaxy formation and evolution. Such diffuse radiation from near-UV to far-infrared wavelengths can interact with $γ$-rays from distant sources such as active galactic nuclei (AGNs), and is responsible for the high-energy absorption observed in their spectra. However, probing the EBL from $γ$-ray spectra of AGNs is not trivial due to internal processes that can mimic its effect. Such processes are usually taken into account in terms of curvature of the intrinsic spectrum. Hence, an improper choice of parametrization for the latter can seriously affect EBL reconstruction. In this paper, we propose a statistical approach that avoids a priori assumptions on the intrinsic spectral curvature and that, for each source, selects the best-fit model on a solid statistical basis. By combining the ${\it Fermi}$-LAT observations of 490 blazars, we determine the $γ$-ray-inferred level of EBL for various state-of-the-art EBL models. We discuss the EBL level obtained from the spectra of both BL Lacs and flat spectrum radio quasars (FSRQ) in order to investigate the impact of internal absorption in different classes of objects. We further scrutinize constraints on the EBL evolution from $γ$-ray observations by reconstructing the EBL level in four redshift ranges, up to $z\sim2.5$. The approach implemented in this paper, carefully addressing the question of the modeling of the intrinsic emission at the source, can serve as a solid stepping stone for studies of hundreds of high-quality spectra acquired by next-generation $γ$-ray instruments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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