论文标题

限制哈勃常数及其下限

Constraining the Hubble constant and its lower limit from the proper motion of extragalactic radio jets

论文作者

Hsiao, Tiger Yu-Yang, Goto, Tomotsugu, Hashimoto, Tetsuya, Santos, Daryl Joe D., Wong, Yi Hang Valerie, Kim, Seong Jin, Raquel, Bjorn Jasper R., Ho, Simon C. -C., Chen, Bo-Han, Kilerci, Ece, Lu, Ting-Yi, On, Alvina Y. L., Lin, Yu-Wei, Wu, Cossas K. -W.

论文摘要

哈勃常数($ h_ {0} $)是描述当前时代宇宙膨胀率的测量值。但是,早期宇宙和晚期宇宙的测量值之间存在$4.4σ$的差异。在这项研究中,我们提出了一种无模型和无距离的方法来约束$ h_ {0} $。将弗里德曼 - 莱玛 - 罗伯逊 - 罗伯逊 - 罗伯逊 - 罗伯逊 - 罗伯逊 - 罗伯逊 - 罗伯逊 - 罗伯逊 - 宇宙学与$ h_ {0} $的下限($ h _ {\ rm 0,min} $)的适当运动的几何关系结合在一起,只能使用三个无环形的观测值来确定$ h_ {0} $的$ h_ {0} $。喷气机。使用这些,我们建议在$ h _ {\ rm 0,min} $之间使用Kolmogorov-Smirnov测试(K-S测试)来区分宇宙学。我们模拟了100、200和500次静脉外射流,具有3个适当运动的准确性($μ__{a} $和$μ__{r} $),$ 10 \%$,$ 5 \%\%$,$ 1 \%$,与当前和未来无线电台的准确性相通用。我们在模拟样本之间执行K-S测试作为具有不同$ H_ {0} $的理论分布,以及JET和模拟观察数据的速度分布的幂律索引。我们的结果表明,增加样本量会导致对幂律指数和中等准确性的哈勃常数(即$ 10 \%$和$ 5 \%$)的严格限制,而$ 1 \%$ $的准确性则增加了样本量,导致对势力法指数的更严格约束。在所有情况下,提高准确性与幂律指数相比,在哈勃常数方面的限制更好,但它减轻了堕落。

The Hubble constant ($H_{0}$) is a measurement to describe the expansion rate of the Universe in the current era. However, there is a $4.4σ$ discrepancy between the measurements from the early Universe and the late Universe. In this research, we propose a model-free and distance-free method to constrain $H_{0}$. Combining Friedman-Lemaître-Robertson-Walker cosmology with geometrical relation of the proper motion of extragalactic jets, the lower limit ($H_{\rm 0,min}$) of $H_{0}$ can be determined using only three cosmology-free observables: the redshifts of the host galaxies, as well as the approaching and receding angular velocities of radio jets. Using these, we propose to use the Kolmogorov-Smirnov test (K-S test) between cumulative distribution functions of $H_{\rm 0,min}$ to differentiate cosmology. We simulate 100, 200, and 500 extragalactic jets with 3 levels of accuracy of the proper motion ($μ_{a}$ and $μ_{r}$), at $10\%$, $5\%$, and $1\%$, corresponding to the accuracies of the current and future radio interferometers. We perform K-S tests between the simulated samples as theoretical distributions with different $H_{0}$ and power-law index of velocity distribution of jets and mock observational data. Our result suggests increasing sample sizes leads to tighter constraints on both power-law index and the Hubble constant at moderate accuracy (i.e., $10\%$ and $5\%$) while at $1\%$ accuracy, increasing sample sizes leads to tighter constraints on power-law index more. Improving accuracy results in better constraints in the Hubble constant compared with the power-law index in all cases but it alleviates the degeneracy.

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