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arXiv 1703.06110astro-ph.GAgr-qc
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高红移转动曲线和MOND

High-redshift rotation curves and MOND

Mordehai Milgrom

摘要:

Genzel等人最近发表了六个高红移盘星系($z\sim 0.9-2.4$)的自转曲线,他们发现在研究半径内“重子占优”。虽然没有达到可用于分析附近宇宙的数据所提供的标准,但这些数据在约束DM场景的宇宙学演化方面是有价值的,或者-正如我在这里讨论的-MOND的$z$依赖性。事实上,这些结果,如果采取表面价值,教我们有用的教训与MOND。a. Genzel等人发现的半光半径处的动力学加速度,与在附近宇宙中测量的MOND加速度常数:$g(R_{1/2})= (3-11)a_0$相比,是相当高的。然后,MOND预测在$R_{1/2}$中的“幻影物质”的分数最多为几十分之一,这与Genzel等人的发现非常吻合。B. MOND根据Genzel等人的重子质量估计预测的渐近旋转速度($0.55-0.75$)大大低于RC的最大速度。因此,MOND预测RC将大幅下降,超过最大值。这也与Genzel等人的发现一致。C.可以说,最重要的教训是,Genzel等人的发现对$a_0$随宇宙时间的可能变化提出了非常有意义的限制。例如,它们几乎都排除在$z\sim 2$处的$\sim 4a_0$的MOND常数的值,排除例如,$a_0\propto (1+z)^{3/2}$。

英文摘要:

Genzel et al. have recently published the rotation curves of six high-redshift disc galaxies ($z\sim 0.9-2.4$), which they find to be `baryon dominated' within the studies radii. While not up to the standard afforded by data available for analysis in the nearby Universe, these data are valuable in constraining cosmological evolution of either DM scenarios, or -- as I discuss here -- $z$-dependence of MOND. Indeed, these results, if taken at face value, teach us useful lessons in connection with MOND. a. The dynamical accelerations at the half-light radii, found by Genzel et al., are rather high compared with the MOND acceleration constant, as measured in the nearby Universe: $g(R_{1/2})= (3-11)a_0$. MOND then predicts fractions of `phantom matter' at $R_{1/2}$ of at most a few tens of percents, which, galaxy by galaxy, agree well with what Genzel et al. find. b. The asymptotic rotational speeds predicted by MOND from the baryonic-mass estimates of Genzel et al. are substantially lower ($0.55-0.75$) than the maximal speeds of the RCs. MOND thus predicts a substantial decline of the RCs beyond the maximum. This too is in line with what Genzel et al. find. c. Arguably, the most important lesson is that the findings of Genzel et al. cast very meaningful constraints on possible variation of $a_0$ with cosmic time. For example, they all but exclude a value of the MOND constant of $\sim 4a_0$ at $z\sim 2$, excluding, e.g., $a_0\propto (1+z)^{3/2}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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