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arXiv 1002.3820astro-ph.HEastro-ph.COastro-ph.GAhep-ph
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Fermi-LAT各向同性扩散Gamma-Ray背景谱对暗物质的守恒约束

Conservative Constraints on Dark Matter from the Fermi-LAT Isotropic Diffuse Gamma-Ray Background Spectrum

Kevork N. Abazajian, Prateek Agrawal, Zackaria Chacko, Can Kilic

摘要:

我们研究了费米伽马射线空间望远镜上的大面积望远镜对各向同性漫射伽马射线背景的测量对弱相互作用大质量粒子(WIMP)候选暗物质湮灭成各种标准模型终态的终态辐射的约束。预期的各向同性扩散信号从暗物质湮灭有贡献的本地银河系(MW)以及河外暗物质。来自MW的信号对所采用的晕的暗物质轮廓非常不敏感,并且主导来自河外晕的信号,该信号对晕质量函数的低质量截止敏感。对于低晕质量的生存截止和银河系和河外组分的子结构增强因子,我们采用保守的模型,只考虑初级末态辐射。这提供了强大的约束,达到热生产横截面的低质量WIMP湮灭成强子模式。我们还重新分析限制HESS观测银河脊地区使用保守的模型的暗物质晕配置文件。当与HESS约束相结合时,各向同性扩散谱排除了基于暗物质湮灭为两个轻子末态的PAMELA正电子过剩的所有解释。通过新的中间态湮灭成四个轻子,虽然受到数据的限制,但并不排除。

英文摘要:

We examine the constraints on final state radiation from Weakly Interacting Massive Particle (WIMP) dark matter candidates annihilating into various standard model final states, as imposed by the measurement of the isotropic diffuse gamma-ray background by the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope. The expected isotropic diffuse signal from dark matter annihilation has contributions from the local Milky Way (MW) as well as from extragalactic dark matter. The signal from the MW is very insensitive to the adopted dark matter profile of the halos, and dominates the signal from extragalactic halos, which is sensitive to the low mass cut-off of the halo mass function. We adopt a conservative model for both the low halo mass survival cut-off and the substructure boost factor of the Galactic and extragalactic components, and only consider the primary final state radiation. This provides robust constraints which reach the thermal production cross-section for low mass WIMPs annihilating into hadronic modes. We also reanalyze limits from HESS observations of the Galactic Ridge region using a conservative model for the dark matter halo profile. When combined with the HESS constraint, the isotropic diffuse spectrum rules out all interpretations of the PAMELA positron excess based on dark matter annihilation into two lepton final states. Annihilation into four leptons through new intermediate states, although constrained by the data, is not excluded.

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