Galaxy-cluster-stacked Fermi-LAT. Part II. Extended central hadronic signal

IF 5.9 2区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Journal of Cosmology and Astroparticle Physics Pub Date : 2025-10-01 DOI:10.1088/1475-7516/2025/10/016

Uri Keshet

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Abstract

Faint γ-ray signatures emerge in Fermi-LAT data stacked scaled to the characteristic θ500 angles of MCXC galaxy clusters. After Paper I of this series thus discovered virial shocks, later supported in other bands, this second paper focuses on cluster cores. Stacking 1–100 GeV source-masked data around clusters shows a significant (4.7σ for 75 clusters) and extended central excess, inconsistent with central point sources. The resolved signal is best fit (3.7σ TS-test) as hadronic emission from a cosmic-ray ion (CRI) distribution that is flat both spectrally (p ≡ 1 - dlnu/dlnE = 2.0 ± 0.3) and spatially (CRI-to-gas index σ = 0.1 ± 0.4), carrying an energy density du(0.1θ500)/dlnE = 10-13.6±0.5 erg cm-3 at E = 100 GeV energy; insufficient resolution would appear to raise p and σ. Such CRI match the long-predicted distribution needed to power diffuse intracluster radio emission in its various forms (mini-halos, giant halos, standard relics, their transitional forms, and mega-halos), disfavoring models that invoke electron (re)acceleration in weak shocks or turbulence. Stringent upper limits on residual γ-ray emission, e.g. from dark-matter annihilation, are imposed.

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Galaxy-cluster-stacked Fermi-LAT。第二部分。扩展中心强子信号

微弱的γ射线特征出现在Fermi-LAT数据中，这些数据以MCXC星系团的θ500角度堆叠。在本系列的第1篇论文发现了viral冲击（后来在其他波段得到了支持）之后，第二篇论文将重点放在了集群核心上。在聚类周围叠加1 ~ 100 GeV源掩码数据显示出显著的中心过剩（75个聚类为4.7σ）和扩展的中心过剩，与中心点源不一致。在宇宙射线离子（CRI）的光谱上（p≡1 - dlnE /dlnE = 2.0±0.3）和空间上（CRI-to-gas指数σ = 0.1±0.4）为平坦分布，在E = 100 GeV能量下，其能量密度du(0.1θ500)/dlnE = 10-13.6±0.5 erg cm-3，最适合（3.7σ ts测试）作为强子发射；分辨率不足似乎会提高p和σ。这样的CRI符合长期预测的分布，需要为各种形式的星系团内漫射射电发射提供动力（迷你晕，巨大晕，标准遗迹，它们的过渡形式和超级晕），不利于在弱冲击或湍流中调用电子（再）加速的模型。对残余γ射线发射，如暗物质湮灭，施加了严格的上限。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Cosmology and Astroparticle Physics 地学天文-天文与天体物理

CiteScore

10.20

自引率

23.40%

发文量

632

审稿时长

1 months

期刊介绍： Journal of Cosmology and Astroparticle Physics (JCAP) encompasses theoretical, observational and experimental areas as well as computation and simulation. The journal covers the latest developments in the theory of all fundamental interactions and their cosmological implications (e.g. M-theory and cosmology, brane cosmology). JCAP''s coverage also includes topics such as formation, dynamics and clustering of galaxies, pre-galactic star formation, x-ray astronomy, radio astronomy, gravitational lensing, active galactic nuclei, intergalactic and interstellar matter.