论文标题
从21厘米边缘数据的无金属恒星形成速率密度的提示
A hint on the metal-free star formation rate density from 21cm-EDGES data
论文作者
论文摘要
我们旨在提供对无金属（人口III; POP III）星形密度密度$ \dotρ_{*}^{III} $的第一个数据约束估计，以便再现Edge and Edge and Edges 21-CM Global 21-CM Global 21-CM Global odshifts（$ Z \ gtrsim 16 $）所需的必需。我们的模型是Lyman Alpha（Ly $α$），POP III和富含金属的人口II（POP II）恒星的无线电和X射线背景。对于后者，我们使用{\ it delphi}半分析模型的恒星形成速率密度估计（和LY $α$背景），该模型已被证明在$ z \ gtrsim 5 $上以$ z \ gtrsim 5 $的星系的所有关键可观测值进行了重现；无线电和X射线背景是使用低$ z $值固定的。使用Markov链蒙特卡洛分析获得了表征流行III恒星特性的自由参数的约束。 Our results yield a $\dotρ_{*}^{III}$ that whilst increasing from $z \sim 21-16$ thereafter shows a sharp decline which is in excellent agreement with the results found by \citet{valiante2016} to simulate the growth of $z \sim 6 - 7$ quasars and their host galaxies, suggesting that the bulk of Pop III star formation occurs in the rarest and $ z \ Lessim 20 $的最巨大的金属罚款光环。这使流行III星可以在$ z \ sim 21-15 $之间生产出快速增长的$α$背景。此外，流行III星团必须提供一个无线电背景，该背景比Pop II恒星所提供的$ 3-4 $数量级约3-4美元，尽管Pop II恒星主导了X射线背景。
We aim to provide the first data-constrained estimate of the metal-free (Population III; Pop III) star formation rate density $\dotρ_{*}^{III}$ required at high-redshifts ($z \gtrsim 16$) in order to reproduce both the amplitude and the redshift of the EDGES 21-cm global signal. Our model accounts for the Lyman Alpha (Ly$α$), radio and X-ray backgrounds from both Pop III and metal-enriched Population II (Pop II) stars. For the latter, we use the star formation rate density estimates (and the Ly$α$ background) from the {\it Delphi} semi-analytic model that has been shown to reproduce all key observables for galaxies at $z \gtrsim 5$; the radio and X-ray backgrounds are fixed using low-$z$ values. The constraints on the free parameters characterizing the properties of the Pop III stars are obtained using a Markov Chain Monte Carlo analysis. Our results yield a $\dotρ_{*}^{III}$ that whilst increasing from $z \sim 21-16$ thereafter shows a sharp decline which is in excellent agreement with the results found by \citet{valiante2016} to simulate the growth of $z \sim 6 - 7$ quasars and their host galaxies, suggesting that the bulk of Pop III star formation occurs in the rarest and most massive metal-poor halos at $z \lesssim 20$. This allows Pop III stars to produce a rapidly growing Ly$α$ background between $z \sim 21-15$. Further, Pop III stars are required to provide a radio background that is about $3-4$ orders of magnitude higher than that provided by Pop II stars although Pop II stars dominate the X-ray background.
