Multi-messenger constraints on Abelian-Higgs cosmic string networks
Multi-messenger constraints on Abelian-Higgs cosmic string networks
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DOI：
10.1088/1475-7516/2023/04/045
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发表时间：
2022-10
影响因子：
6.4
通讯作者：
M. Hindmarsh;J. Kume
中科院分区：
文献类型：
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作者：
M. Hindmarsh;J. Kume
阿贝尔-希格斯（AH）模型中的Nielsen-Olesen涡旋是规范场论中宇宙弦的最简单的实现。大尺度数值解表明，由随机初始条件产生的AH弦网络的主要衰变通道是经典场辐射。然而，他们也表明，在特殊的初始条件下，可以创建弦环，其中经典场辐射被抑制，并且表现得像Nambu-Goto（NG）弦，具有进入引力辐射的主导衰变通道。这表明宇宙弦一般是高能粒子和引力波的来源。在这里，我们采用了一个简单的参数化的AH弦网络允许粒子和引力波的生产。参照NG样环分布的特定模型，这为该模型的“多信使”调查奠定了基础。我们发现，为了解释NANOGrav探测到的可能的引力波背景，同时满足模拟和宇宙微波背景的约束，在普朗克单位Gμ和NG类环的分数f NG的AH弦的张力应满足Gμ f NG 2.6 <$3.2 × 10-13在95%的置信度。另一方面，对于这样的弦张力，来自漫射伽马射线背景（DGRB）的约束表明，超过97%的总网络能量应该转换为暗物质（DM）或暗辐射。我们还考虑联合约束的湮灭截面，质量，和遗迹丰富的DM产生的字符串衰变。例如，对于500 GeV的DM质量，观测到的遗迹丰度可以通过衰减的AH弦来解释，这也解释了NANOGrav信号。
Nielsen-Olesen vortices in the Abelian-Higgs (AH) model are the simplest realisations of cosmic strings in a gauge field theory. Large-scale numerical solutions show that the dominant decay channel of a network of AH strings produced from random initial conditions is classical field radiation. However, they also show that with special initial conditions, loops of string can be created for which classical field radiation is suppressed, and which behave like Nambu-Goto (NG) strings with a dominant decay channel into gravitational radiation. This indicates that cosmic strings are generically sources of both high-energy particles and gravitational waves. Here we adopt a simple parametrisation of the AH string network allowing for both particle and gravitational wave production. With a reference to a specific model for NG-like loop distribution, this sets the basis for a “multi-messenger” investigation of this model. We find that, in order to explain the NANOGrav detection of a possible gravitational wave background, while satisfying the constraint on NG-like loop production from simulations and bounds from the cosmic microwave background, the tension of the AH string in Planck units Gμ and the fraction of the NG-like loops f NG should satisfy Gμ f NG 2.6 ≳ 3.2 × 10-13 at 95% confidence. On the other hand, for such string tensions, constraints from the diffuse gamma-ray background (DGRB) indicate that more than 97% of the total network energy should be converted to dark matter (DM) or dark radiation. We also consider joint constraints on the annihilation cross-section, the mass, and the relic abundance of DM produced by decays of strings. For example, for a DM mass of 500 GeV, the observed relic abundance can be explained by decaying AH strings that also account for the NANOGrav signal.