A cosmic UV/X-ray background model update
A cosmic UV/X-ray background model update
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DOI：
10.1093/mnras/staa302
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发表时间：
2020-04-01
影响因子：
4.8
通讯作者：
Faucher-Giguere, Claude-Andre
中科院分区：
文献类型：
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作者：
Faucher-Giguere, Claude-Andre
我们提出了一个更新的宇宙电离背景模型，从紫外线到X射线。相对于我们以前的模型，新模型提供了一个更好的匹配大量的最新的经验约束，包括：（1）新的星系和活动星系核光度函数，（2）恒星光谱，包括双星，（3）遮蔽和未遮蔽的活动星系核，（4）非电离紫外背景的测量，（5）非电离紫外背景的测量。（5）在z近似为0-6时测量星系际H I和He II的光电离率;（6）局部X射线背景;（7）改进星系际不透明度的测量。在这个模型中，活动星系核在z小于或接近3处占据H电离背景，而恒星形成星系在更高的红移处占据主导地位。结合急剧下降的活动星系核光度函数超过z类似于2，H I电离率的缓慢演变推断高红移HI Ly α森林需要从恒星形成星系的逃逸分数，增加红移（人口平均逃逸分数约为1%，足以使星系际介质在z = 3时，包括来自活动星系核的贡献）。我们提供了有效的光电离和光加热率校准，以匹配普朗克2018再电离光学深度和最近的限制，从He II Ly α森林在流体动力学模拟。
We present an updated model of the cosmic ionizing background from the UV to the X-rays. Relative to our previous model, the new model provides a better match to a large number of up-to-date empirical constraints, including: (1) new galaxy and AGN luminosity functions; (2) stellar spectra including binary stars; (3) obscured and unobscured AGN; (4) a measurement of the non-ionizing UV background; (5) measurements of the intergalactic H I and He II photoionization rates at z similar to 0-6; (6) the local X-ray background; and (7) improved measurements of the intergalactic opacity. In this model, AGN dominate the H ionizing background at z less than or similar to 3 and star-forming galaxies dominate it at higher redshifts. Combined with the steeply declining AGN luminosity function beyond z similar to 2, the slow evolution of the H I ionization rate inferred from the high-redshift HI Ly alpha forest requires an escape fraction from star-forming galaxies that increases with redshift (a population-averaged escape fraction of approximate to 1 per cent suffices to ionize the intergalactic medium at z = 3 when including the contribution from AGN). We provide effective photoionization and photoheating rates calibrated to match the Planck 2018 reionization optical depth and recent constraints from the He II Ly alpha forest in hydrodynamic simulations.