论文标题
关于高红移的巨大星系星系的电离辐射的低逃生径流的起源
On the origin of low escape fractions of ionizing radiation from massive star-forming galaxies at high redshift
论文作者
论文摘要
从$ z \ sim3 $ - $ 4 $衍生出的电离辐射的低逃生辐射分数的物理起源尚不清楚。我们执行理想化的圆盘银河模拟，以了解金属性和气体等银河系特性如何使用具有强烈恒星反馈的辐射流动力学模拟来影响Lyman Continuum（Lyc）光子的逃脱。我们发现，从质量$ $ $ $ m_h \ simeq10^{11} \，m_ \ odot $是$ \ odot $ is $ \ \ weft <f _ {\ rm eSc}^{\ rm eSc}^{\ rm rm 3d $ \ y \ y \ right \ rim prime $ m_h \ odot $ rm odot $ rm rm eSc}^{ LYC光子的大约一半被吸收在100 pc的尺度内，另一半被吸收在ISM中（$ \ sillsim 2 \，{\ rm kpc} $）。当气体的金属性增加到$ z = 0.02 $时，逃生分数将显着降低至$ \ weft <f _ {\ rm Esc}^{\ rm 3d} \ right> \ right> \ simeq1 \％$，因为年轻的恒星被他们的生物云延长了更长的时间。相反，将气体质量增加5倍，导致$ \ weft <f _ {\ rm Esc}^{\ rm 3d} \ right> \ simeq 5 \，\％$，因为lyc光子仅由厚圆盘中度地吸收。我们的实验表明，高金属性可能更负责在巨大的星形星系中观察到的低逃逸部分，这支持了随着晕光质量增加而降低逃生部分的情况。最后，观察到恒星形成或银河流出速率的逃逸分数和表面密度之间的相关性可忽略不计。
The physical origin of low escape fractions of ionizing radiation derived from massive star-forming galaxies at $z\sim3$-$4$ is not well understood. We perform idealised disc galaxy simulations to understand how galactic properties such as metallicity and gas mass affect the escape of Lyman Continuum (LyC) photons using radiation-hydrodynamic simulations with strong stellar feedback. We find that the luminosity-weighted escape fraction from a metal-poor ($Z=0.002$) galaxy embedded in a halo of mass $M_h\simeq10^{11}\,M_\odot$ is $\left<f_{\rm esc}^{\rm 3D}\right>\simeq 10\,\%$. Roughly half of the LyC photons are absorbed within scales of 100 pc, and the other half is absorbed in the ISM ($\lesssim 2\, {\rm kpc}$). When the metallicity of the gas is increased to $Z=0.02$, the escape fraction is significantly reduced to $\left<f_{\rm esc}^{\rm 3D}\right>\simeq1\%$ because young stars are enshrouded by their birth clouds for a longer time. In contrast, increasing the gas mass by a factor of 5 leads to $\left<f_{\rm esc}^{\rm 3D}\right>\simeq 5\, \%$ because LyC photons are only moderately absorbed by the thicker disc. Our experiments suggest that high metallicity is likely more responsible for the low escape fractions observed in massive star-forming galaxies, supporting the scenario in which the escape fraction is decreasing with increasing halo mass. Finally, negligible correlation is observed between the escape fraction and surface density of star formation or galactic outflow rates.
