斯巴鲁测光观测中天龙座矮星系的中心恒星耗竭
Central stellar depletion in the Draco dwarf from Subaru photometry
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中文总结 AI 辅助
研究通过斯巴鲁测光分析天龙座矮星系，发现其存在中心恒星耗竭的特征，该特征或反映真实物理结构，而非观测拥挤效应。
中文摘要 AI 辅助
暗物质子晕是标准宇宙学模型的基本预言，但它们的低质量群体仍难以通过观测约束。近期研究表明，子晕与矮椭球星系的相互作用会在其恒星表面密度场中引发大规模非平衡涨落，可通过基于傅里叶的统计方法识别。我们将该形式体系应用于天龙座矮星系的斯巴鲁深场测光数据，将此前的测试扩展至$\boldsymbol{\rm O}(10^4)$颗以上的解析恒星。我们利用人工恒星测试为每颗恒星赋予完整性权重，并将其纳入基于离散似然的框架。与核型轴对称Plummer模型相比，天龙座星系呈现出径向波纹，在滤波归一化残差中表现为中心恒星耗竭，周围环绕着环状过量分布；该特征在傅里叶空间中表现为信噪比$\boldsymbol{\rm S/N}=6.0$的低频峰。独立地，采用$\boldsymbol{\rm \beta\beta\beta}$模型拟合表面密度$\boldsymbol{\rm \beta}$时，在>99.9%置信度下得到$\boldsymbol{\rm d}\boldsymbol{\rm \beta}/\boldsymbol{\rm d}R>0$，即朝向中心递减的轮廓。尽管这些信号尚不能视为暗物质子晕的有力证据，但它们表明矮星系的中心恒星耗竭可能反映真实物理结构，而非单纯的拥挤效应。
英文摘要
Dark matter subhaloes are a fundamental prediction of the standard cosmological model, but their low-mass population remains difficult to constrain observationally. Recent work has shown that interactions between subhaloes and dwarf spheroidal galaxies can induce large-scale, out-of-equilibrium fluctuations in their stellar surface density fields, identifiable through Fourier-based statistics. We apply this formalism to deep Subaru photometry of the Draco dwarf, extending previous tests to $\gtrsim\mathcal{O}(10^{4})$ resolved stars. We use artificial-star tests to assign completeness weights to individual stars and incorporate them into a discrete likelihood-based framework. Relative to a cored axisymmetric Plummer model, Draco shows radial corrugations that appear in the filtered normalised residuals as a central stellar depletion surrounded by a ring-like excess. The same feature appears in Fourier space as a low-frequency peak with a signal-to-noise ratio ${\rm S/N}=6.0$. Independently, fitting the surface density $Σ$ with an $αβγ$ model yields ${\rm d}Σ/{\rm d}R>0$ at $>99.9\%$ confidence -- i.e., a profile that decreases towards the centre. Although these signatures cannot yet be regarded as robust evidence for dark subhaloes, they suggest that central stellar depletion in dwarf galaxies may reflect genuine physical structure rather than crowding alone.
发表机构
- Institute for Astronomy, University of Edinburgh（爱丁堡大学天文研究所）
- Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK（英国爱丁堡黑门山皇家天文台）
- Astronomical Science Program, The Graduate University for Advanced Studies, SOKENDAI（日本国立综合研究大学院大学天文学科学项目）
- National Astronomical Observatory of Japan（日本国立天文台）
- Institute of Corpuscular Physics (IFIC), CSIC–Universitat de València（瓦伦西亚大学-CSIC粒子物理研究所）
- VALER, Calle Mayor, 83, 1, 12001 Castellón de la Plana, Spain（西班牙卡斯特利翁德拉普拉纳大街83号1单元VALER）
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