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arXiv 2109.11291astro-ph.COastro-ph.GAastro-ph.HE
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费米大天区望远镜在矮不规则星系中寻找暗物质

Dark Matter search in dwarf irregular galaxies with the Fermi Large Area Telescope

V. Gammaldi, J. Pérez-Romero, J. Coronado-Blázquez, M. Di Mauro, E. V. Karukes, M. A. Sánchez-Conde, P. Salucci

备注：
19 pages, 9 figures, Accepted for Publication in PRD
发表信息：
Phys. Rev. D 104, 083026 (2021)
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摘要：

我们分析了11年的费米-LAT数据对应的7个矮不规则（dIrr）星系的天空区域。DIrrs是暗物质（DM）占主导地位的系统，建议作为有趣的目标，间接搜索DM与伽马射线。星系代表了有趣的情况下，从观测和数值模拟推断的密度分布（核心与尖）之间的强烈分歧。在这项工作中，我们通过考虑两种不同的DM轮廓来解决这个问题，基于对旋转曲线的拟合（在这种情况下是Burkert核心轮廓）和N体宇宙学模拟的结果（即，NFW尖突剖面）。在我们的分析中，我们还包括晕子结构，预计这将使DM信号在诸如dIrrs的晕中提高10倍。对于每个DM模型和dIrr，我们创建了一个空间模板的预期DM诱导的伽马射线信号用于费米LAT数据的分析。在我们的样品中没有从任何目标检测到显著的发射。因此，我们计算DM湮灭截面与质量参数空间的上限。在7个dIrrs中，我们发现IC 10和NGC 6822产生最严格的个体约束，独立于所采用的DM配置文件。我们还产生合并DM限制的样品中的所有对象，这原来是占主导地位的IC 10的所有DM模型和湮灭通道，即$b\bar{b}$，$τ^+τ^-$和$W^+W^-$。最强的约束获得的$b\bar{b}$和$\langleσv \rangle \sim 7 \times 10^{-26}\text{cm}^{3}\text{s}^{-1}$在$m_χ\sim 6$ GeV的水平。虽然这些限制是一个因素的3高于热遗迹截面在低WIMP质量，他们是独立的，并补充那些通过其他目标。

英文摘要：

We analyze 11 years of Fermi-LAT data corresponding to the sky regions of 7 dwarf irregular (dIrr) galaxies. DIrrs are dark matter (DM) dominated systems, proposed as interesting targets for the indirect search of DM with gamma rays. The galaxies represent interesting cases with a strong disagreement between the density profiles (core vs. cusp) inferred from observations and numerical simulations. In this work, we addressed the problem by considering two different DM profiles, based on both the fit to the rotation curve (in this case a Burkert cored profile) and results from N-body cosmological simulations (i.e., NFW cuspy profile). We also include halo substructures in our analysis, which is expected to boost the DM signal a factor of ten in halos such as those of dIrrs. For each DM model and dIrr, we create a spatial template of the expected DM-induced gamma-ray signal to be used in the analysis of Fermi-LAT data. No significant emission is detected from any of the targets in our sample. Thus, we compute upper limits on the DM annihilation cross-section versus mass parameter space. Among the 7 dIrrs, we find IC10 and NGC6822 to yield the most stringent individual constraints, independently of the adopted DM profile. We also produce combined DM limits for all objects in the sample, which turn out to be dominated by IC10 for all DM models and annihilation channels, i.e. $b\bar{b}$, $τ^+τ^-$ and $W^+W^-$. The strongest constraints are obtained for $b\bar{b}$ and are at the level of $\langleσv \rangle \sim 7 \times 10^{-26}\text{cm}^{3}\text{s}^{-1}$ at $m_χ\sim 6$ GeV. Though these limits are a factor of 3 higher than the thermal relic cross section at low WIMP masses, they are independent from and complementary to those obtained by means of other targets.

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