论文标题
SKA实验中的EOR信号的银河无免费发射对前景的贡献
Contribution of Galactic free-free emission to the foreground for EoR signal in SKA experiments
论文作者
论文摘要
压倒性的前景污染阻碍了在电离时期（EOR）期间中性氢的21 cm信号的准确检测。在各种前景组件中，研究较少的无银河空发射，因此它对EOR观察结果的影响尚不清楚。在这项工作中，我们采用了观察到的$ \ rmHα$强度图，并校正了吸收灰尘和散射，SIMFAST21软件以及最新的SKA1-LOW布局配置，以模拟SKA“观察到的“观察到的”图像“无河流免费发射和EOR信号”的图像。 By calculating the one-dimensional power spectra from the simulated image cubes, we find that the Galactic free-free emission is about $10^{3.5}$-$10^{2.0}$, $10^{3.0}$-$10^{1.3}$, and $10^{2.5}$-$10^{1.0}$ times more luminous than the EoR signal on scales of $ 0.1〜 \ rm mpc^{ - 1} <k <2〜 \ rm mpc^{ - 1} $ in $ 116 $ - $ 124 $，$ 146 $ - $ 154 $和$ 186 $ - $ 194 $ $ $ {\ rm MHz} $ freefeny Bands。 We further analyse the two-dimensional power spectra inside the properly defined EoR window and find that the leaked Galactic free-free emission can still cause non-negligible contamination, as the ratios of its power (amplitude squared) to the EoR signal power can reach about $200\%$, $60\%$, and $15\%$ on scales of $1.2~\rm Mpc^{-1}$ in分别三个频带。因此，我们得出的结论是，作为严重污染的前景成分，无银河的自由发射需要在即将到来的深度EOR观察中进行仔细处理。
The overwhelming foreground contamination hinders the accurate detection of the 21-cm signal of neutral hydrogen during the Epoch of Reionization (EoR). Among various foreground components, the Galactic free-free emission is less studied, so that its impact on the EoR observations remains unclear. In this work, we employ the observed $\rm Hα$ intensity map with the correction of dust absorption and scattering, the Simfast21 software, and the latest SKA1-Low layout configuration to simulate the SKA "observed" images of Galactic free-free emission and the EoR signal. By calculating the one-dimensional power spectra from the simulated image cubes, we find that the Galactic free-free emission is about $10^{3.5}$-$10^{2.0}$, $10^{3.0}$-$10^{1.3}$, and $10^{2.5}$-$10^{1.0}$ times more luminous than the EoR signal on scales of $0.1~\rm Mpc^{-1} < k < 2~\rm Mpc^{-1}$ in the $116$-$124$, $146$-$154$, and $186$-$194$ ${\rm MHz}$ frequency bands. We further analyse the two-dimensional power spectra inside the properly defined EoR window and find that the leaked Galactic free-free emission can still cause non-negligible contamination, as the ratios of its power (amplitude squared) to the EoR signal power can reach about $200\%$, $60\%$, and $15\%$ on scales of $1.2~\rm Mpc^{-1}$ in three frequency bands, respectively. Therefore, we conclude that the Galactic free-free emission, as a severe contaminating foreground component, needs to be carefully treated in the forthcoming deep EoR observations.
