比较宇宙学模拟中的引力波背景预测与脉冲星计时观测
Comparing gravitational wave background predictions from cosmological simulations to pulsar timing observations
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中文总结 AI 辅助
研究脉冲星计时阵列探测到的引力波背景，构建统计框架量化其与理论预测的张力，探讨不同假设影响，应用于模拟与观测对比，还探索黑洞种群修改及模拟体积影响。
中文摘要 AI 辅助
脉冲星计时阵列最近探测到引力波背景，可能是超大质量黑洞双星合并引力波的首个证据。本文提出首个综合统计框架量化脉冲星计时阵列测量与理论预测间的张力，研究不同假设影响，应用于比较模拟与观测，还探索黑洞种群修改及模拟体积影响。
英文摘要
The recent detection of a gravitational wave background (GWB) by pulsar timing arrays (PTAs) may represent the first evidence of gravitational waves from merging supermassive black hole binaries, opening a new window on the low-frequency end of the gravitational wave spectrum. These inspiralling binaries are expected to dominate the signal, although most theoretical models seem to predict somewhat lower amplitudes than what is observed. We present the first comprehensive statistical framework to quantify the tension between PTA measurements and theoretical predictions, maximising the constraining power of current data and allowing straightforward application to future PTA datasets. We further investigate how different assumptions in the observational inference, particularly the use of a power-law model for the GWB spectrum, can bias tension estimates and potentially overstate discrepancies with theory. We apply our framework to compare predictions from the FABLE cosmological simulation with the NANOGrav 15-year dataset. For our fiducial black hole population, we find tension values of $1σ$-$2.5σ$, indicating no statistically significant disagreement with the observations. We further explore physically motivated modifications to the merging black hole population, guided by electromagnetic observations and theoretical uncertainties. In particular, scenarios with boosted black hole masses at high redshift and more equal-mass mergers substantially increase the predicted GWB amplitude, improving agreement with PTA data. Finally, we investigate the high-mass end of the black hole mass function and the impact of finite simulation volume. We find that the $(100 \, \mathrm{cMpc} \, h^{-1})^3$ FABLE box is sufficient to robustly predict the GWB signal at the most constraining frequency.
发表机构
- University of Cambridge（剑桥大学）
- Kavli Institute for Cosmology, Cambridge (KICC), University of Cambridge（剑桥卡弗里宇宙学研究所）
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge（剑桥大学数学科学中心应用数学与理论物理系）
- Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire（赫特福德大学物理、天文与数学系天体物理学研究中心）
- Università di Milano - Bicocca（米兰比可卡大学）
- INAF, Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）
- INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所米兰-比可卡分部）
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