eROSITA宇宙学与星系群：到位力半径的热气体预算

中文摘要 AI 辅助

将热气体排出星系群和星系团位力区域之外的非引力过程，统称为重子反馈，在Mpc尺度上重塑宇宙物质分布中起着关键作用。我们使用eROSITA对从eROSITA-DE数据首次公开释放（eRASS1）中选取的25个完整星系群样本的观测结果，这些星系群通过2微米红移巡天光学星系群表（2MRS）识别。我们提取并拟合面亮度（SBx）轮廓，给出到$R_{200}$的热气体质量和热气体丰度轮廓。我们对$M_{\text{gas}}-M_{\text{tot}}$、$L_{\text{X}}-M_{\text{tot}}$和$L_{\text{X}}-M_{\text{gas}}$关系进行贝叶斯分析，同时考虑孔径协方差效应。在$R_{500}$处，我们报告均匀平坦的SBx轮廓，其平均$\beta$参数为$0.38\text{pm}0.04$，在$R_{500}$之外陡化为$\beta=0.76\text{pm}0.19$。我们在样本的中位质量$M_{500}=2.54\times10^{13}M_{\odot}$处测量到亚宇宙热气体丰度$f_{\text{gas,500}}=4.32\text{pm}0.42\\%$；同样，在$R_{200}$和中位质量$M_{200}=3.69\times10^{13}M_{\odot}$处，我们得到$f_{\text{gas,200}}=5.78\text{pm}0.69\\%$。我们的$f_{\text{gas}}-M_{\text{tot}}$和$L_{\text{X}}-M_{\text{tot}}$关系与FLAMINGO模拟的强反馈变体预测存在显著偏差（张力为$2.5\sigma$至$8.0\sigma$），而基准FLAMINGO和BAHAMAS与我们的测量结果最为吻合。利用我们测量的重子丰度和\texttt{SP(k)}模型，我们推断在$k=5\\ h\\ \text{Mpc}^{-1}$处，物质功率谱相对于仅暗物质宇宙降低了$10\\%-15\\%$，这与基准FLAMINGO和BAHAMAS一致，同时在更小尺度上与强反馈变体的张力不断增大。

英文摘要

Non-gravitational processes that expel hot gas beyond the virial regions of groups and clusters of galaxies, known collectively as baryonic feedback, play a key role in reshaping the matter distribution of the Universe on Mpc scales. We use eROSITA observations of a complete sample of 25 galaxy groups selected from the first public release of the eROSITA-DE data (eRASS1) and identified with the Two Micron Redshift Survey optical group catalogue (2MRS). We extract and fit surface brightness (SBx) profiles and present hot gas mass and hot gas fraction profiles out to $R_{200}$. We perform a Bayesian analysis of $M_{\mathrm{gas}}-M_{\mathrm{tot}}$, $L_{\mathrm{X}}-M_{\mathrm{tot}}$, and $L_{\mathrm{X}}-M_{\mathrm{gas}}$ relations, taking into account the aperture covariance effects. At $R_{500}$, we report uniformly flat SBx profiles with a mean $β$ parameter of $0.38 \pm0.04$, steepening to $β= 0.76\pm0.19$ beyond $R_{500}$. We measure a sub-cosmic hot gas fraction at the median mass of our sample $M_{500} = 2.54\times10^{13}M_{\odot}$ of $ f_{\mathrm{gas,500}} = 4.32\pm0.42\%$. Similarly, at $R_{200}$ and the median mass $M_{\mathrm{ 200}} = 3.69\times10^{13}M_{\odot}$, we obtain $f_{\mathrm{gas,200}}=5.78\pm0.69\%$. Our $f_{\mathrm{gas}}-M_{\mathrm{tot}}$ and $L_{\mathrm{X}}-M_{\mathrm{tot}}$ relations show significant deviations from the predictions of the strong feedback variants of the FLAMINGO simulation ($2.5σ$ to $8.0σ$ tension), while fiducial FLAMINGO and BAHAMAS provide the closest match to our measurements. Using our measured baryon fractions and the SP(k) model, we infer a $10\%-15\%$ reduction in the matter power spectrum at $k = 5\ h\ \mathrm{Mpc}^{-1}$ relative to a dark matter-only universe, in agreement with fiducial FLAMINGO and BAHAMAS, while revealing a growing tension on smaller scales with the strong feedback variants.

发表机构

• University of Helsinki（赫尔辛基大学）
• University of Geneva（日内瓦大学）
• University of Tartu（塔尔图大学）
• Estonian Academy of Sciences（爱沙尼亚科学院）
• INAF-IASF Milano（意大利国家天体物理研究所米兰分院）
• Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森尼天体物理中心）
• INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano（意大利国家天体物理研究所空间与宇宙物理米兰研究所）

机构由 AI 辅助整理，请以论文原文为准。

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Accepted for publication in A&A