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arXiv 2207.09342astro-ph.GA
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$3 < z < 5$ 处的总静止系紫外光度函数:对 $M_{\rm UV}$ 从 $-28$ 到 $-16$ 的 AGN 和星系的联合研究

The total rest-frame UV luminosity function from $3 < z < 5$: A simultaneous study of AGN and galaxies from $-28<M_{\rm UV}<-16$

N. J. Adams, R. A. A. Bowler, M. J. Jarvis, R. G. Varadaraj, B. Häußler

AI总结:

本研究利用 HSC 和 VISTA 深场数据,测量 $z=3-5$ 的紫外光度函数,联合拟合 AGN 与星系,发现 AGN 演化迅速但不足以独自维持再电离。

摘要:

我们利用分别来自 96894、38655 和 7571 个源的数据,测量了红移 $z=3$、$z=4$ 和 $z=5$ 处的静止系紫外光度函数,以描绘再电离纪元之后不久 AGN 主导与星系主导的紫外发射之间的转变。源的选择采用了综合的光度红移方法,利用了由 HSC 和 VISTA 共同覆盖的 $10$ 平方度的深河外遗留场。模板拟合覆盖了 $0.3\text{--}2.4\mu$m 的波长范围,实现了 $80\text{--}90$% 的完备性,远高于经典的色-色截断方法。测量得到的光度函数覆盖了 $-26<M_{\rm UV}<-19.25$ 的范围。利用其他研究的补充结果,该范围进一步扩展至 $-28.5<M_{\rm UV}<-16$,从而能够对联合的 AGN 和星系光度函数进行同时拟合。我们发现,在 $z\sim3$ 处紫外明亮星系($M_{\rm UV}<-22$)的数量少于 $z\sim4$ 处,这表明在尘埃遮蔽的同时,广泛存在的熄灭过程开始出现;并且 AGN 光度函数的演化非常迅速,其数量密度在 $3<z<6$ 范围内上升了约两个数量级。目前仍难以确定双幂律(DPL)函数形式是否比 Schechter 函数更受青睐来描述星系紫外光度函数。根据我们的紫外光度函数估算氢电离光子预算,我们发现 AGN 可以贡献于但无法独自维持宇宙在 $z=3-5$ 时的再电离。然而,快速演化的 AGN 光度函数强烈不支持其在再电离纪元(EoR)内有显著贡献。

英文摘要:

We present measurements of the rest-frame ultraviolet luminosity function at redshifts $z=3$, $z=4$ and $z=5$, using 96894, 38655 and 7571 sources respectively to map the transition between AGN and galaxy-dominated ultraviolet emission shortly after the epoch of reionization. Sources are selected using a comprehensive photometric redshift approach, using $10$deg$^2$ of deep extragalactic legacy fields covered by both HSC and VISTA. The use of template fitting spanning a wavelength range of $0.3\text{--}2.4μ$m achieves $80\text{--}90$ per cent completeness, much higher than classical colour-colour cut methodology. The measured LF encompasses $-26<M_{\rm UV}<-19.25$. This is further extended to $-28.5<M_{\rm UV}<-16$ using complementary results from other studies, allowing for the simultaneous fitting of the combined AGN and galaxy LF. We find that there are fewer UV luminous galaxies ($M_{\rm UV}<-22$) at $z\sim3$ than $z\sim4$, indicative of an onset of widespread quenching alongside dust obscuration, and that the evolution of the AGN LF is very rapid, with their number density rising by around 2 orders of magnitude from $3<z<6$. It remains difficult to determine if a double power law (DPL) functional form is preferred over the Schechter function to describe the galaxy UV LF. Estimating the Hydrogen ionizing photon budget from our UV LFs, we find that AGN can contribute to, but cannot solely maintain, the reionization of the Universe at $z=3-5$. However, the rapidly evolving AGN LF strongly disfavours a significant contribution within the EoR.

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