发表机构
University of Maryland, College Park; NASA Goddard Space Flight Center; Joint Space-Science Institute, University of Maryland, College Park; University of Illinois at Urbana-Champaign（马里兰大学帕克分校; NASA戈达德太空飞行中心; 马里兰大学联合空间科学研究所; 伊利诺伊大学厄巴纳-香槟分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用类PSR~J0740+6620合成NICER数据，发现氢氦大气不匹配在低斑点-背景比下几乎不引入半径偏差，但在高比值下可导致显著偏差，而贝叶斯证据始终能识别正确大气模型，凸显其用于模型比较的重要性。
AI 中文摘要
对中子星半径的约束有助于揭示其内部冷致密物质的性质。先前使用合成中子星内部成分探测器（NICER）脉冲波形数据的研究表明，由此得出的半径推断对几类建模系统效应具有稳健性。本文基于质量约为2.1倍太阳质量的脉冲星PSR~J0740+6620的合成数据，探讨了假设错误大气成分的后果。我们发现，当合成数据假设氦大气而推断时假设氢大气，或反之，在真实PSR~J0740+6620数据的斑点-背景比下，对推断半径产生的偏差很小。然而，当我们将斑点-背景比提高约20倍，同时保持总计数固定在观测到的约5.5×10^5时，我们发现成分不匹配可能产生显著有偏的半径估计，同时仍隐藏在统计上可接受的残差拟合中。即使在这些情况下，贝叶斯证据也始终能识别出正确的大气模型。我们的发现强调了使用贝叶斯证据进行模型比较和拟合优度检验的重要性。
英文摘要
Constraints on neutron star radii provide insight into the properties of the cold, dense matter in their interiors. Previous studies using synthetic Neutron star Interior Composition Explorer (NICER) pulse waveform data have demonstrated that radius inferences derived therefrom are robust against several classes of modeling systematics. Here we explore the consequences of assuming the wrong atmospheric composition, using synthetic data based on the $\sim 2.1~M_\odot$ pulsar PSR~J0740$+$6620. We find that the assumption of a hydrogen atmosphere when the synthetic data assumed a helium atmosphere, or vice versa, produces little bias in the inferred radius at the spot-to-background ratio of the actual PSR~J0740$+$6620 data. However, when we increase the spot-to-background ratio by a factor of $\sim20$ while keeping the total number of counts fixed at the observed $\sim 5.5\times 10^5$, we find that composition mismatch can produce significantly biased radius estimates while remaining hidden inside a fit with statistically acceptable residuals. Even in these cases, the Bayesian evidence consistently identifies the correct atmospheric model. Our findings reinforce the importance of using the Bayesian evidence for model comparison and goodness-of-fit tests.
Comments23 pages, 10 figures, 6 tables. Accepted to ApJ
