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arXiv 2203.04826astro-ph.GAastro-ph.CO
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HETDEX中320 kpc外Lyman- $α$晕表面亮度分布

Surface Brightness Profile of Lyman-$α$ Halos out to 320 kpc in HETDEX

Maja Lujan Niemeyer, Eiichiro Komatsu, Chris Byrohl, Dustin Davis, Maximilian Fabricius, Karl Gebhardt, Gary J. Hill, Lutz Wisotzki, William P. Bowman, Robin Ci… 展开作者

Maja Lujan Niemeyer, Eiichiro Komatsu, Chris Byrohl, Dustin Davis, Maximilian Fabricius, Karl Gebhardt, Gary J. Hill, Lutz Wisotzki, William P. Bowman, Robin Ciardullo, Daniel J. Farrow, Steven L. Finkelstein, Eric Gawiser, Caryl Gronwall, Donghui Jeong, Martin Landriau, Chenxu Liu, Erin Mentuch Cooper, Masami Ouchi, Donald P. Schneider, Gregory R. Zeimann

摘要:

利用Hobby-Eberly望远镜暗能量实验(HETDEX)的早期观测数据,计算了968个Lyman-$α$发射星系(LAEs)在红移$1.9<z<3.5$处的中层叠加Lyman-$α$表面亮度剖面。选定的LAE是高置信度的Lyman-$α$探测,具有在良好的视宁度条件下观察到的大信噪比(点扩散函数半峰全宽$<1.4"$),不包括活动星系核(AGN)。LAE的Lyman-$α$光度为$10^{42.4}-10^{43}\, \mathrm{erg}\, \mathrm{s}^{-1}$ .我们在从周围的莱曼- $α$晕到$r\simeq 160$千秒差距(物理)的$(3.6\pm 1.3)\times 10^{-20}\,\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{cm}^{-2}\,\mathrm{arcsec}^{-2}$水平上,在中层堆叠径向剖面中探测到微弱的发射。在$r<80\,\mathrm{kpc}$上的中值堆积径向轮廓的形状与用多单元光谱探测器(MUSE)在$3<z<4$上观察到的更暗的LAEs的形状一致,表明中值堆积的莱曼- $α$轮廓在红移$2<z<4$上具有相似的形状,并且在莱曼- $α$光度的$10$的因子上具有相似的形状。虽然我们同意$r<80\,\mathrm{kpc}$的MUSE样品的结果,但我们将轮廓半径扩展了两倍。在$r>80\,\mathrm{kpc}$,我们的轮廓比MUSE模型更平坦。测量的轮廓在大多数半径上与Byrohl等人(2021)在$z=3$进行的宇宙辐射传输模拟中的星系一致。这表明,在$r\lesssim 100$ kpc处,莱曼- $α$晕的表面亮度主要由来自星系中心恒星形成区的莱曼- $α$光子的共振散射所决定,而在$r > 100$ kpc处,莱曼-$α$晕的表面亮度主要由来自周围暗物质晕中星系的光子所决定。

英文摘要:

We present the median-stacked Lyman-$α$ surface brightness profile of 968 spectroscopically selected Lyman-$α$ emitting galaxies (LAEs) at redshifts $1.9<z<3.5$ in the early data of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The selected LAEs are high-confidence Lyman-$α$ detections with large signal-to-noise ratios observed with good seeing conditions (point-spread-function full-width-at-half-maximum $<1.4"$), excluding active galactic nuclei (AGN). The Lyman-$α$ luminosities of the LAEs are $10^{42.4}-10^{43}\, \mathrm{erg}\, \mathrm{s}^{-1}$. We detect faint emission in the median-stacked radial profiles at the level of $(3.6\pm 1.3)\times 10^{-20}\,\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{cm}^{-2}\,\mathrm{arcsec}^{-2}$ from the surrounding Lyman-$α$ halos out to $r\simeq 160$ kpc (physical). The shape of the median-stacked radial profile is consistent at $r<80\,\mathrm{kpc}$ with that of much fainter LAEs at $3<z<4$ observed with the Multi Unit Spectroscopic Explorer (MUSE), indicating that the median-stacked Lyman-$α$ profiles have similar shapes at redshifts $2<z<4$ and across a factor of $10$ in Lyman-$α$ luminosity. While we agree with the results from the MUSE sample at $r<80\,\mathrm{kpc}$, we extend the profile over a factor of two in radius. At $r>80\,\mathrm{kpc}$, our profile is flatter than the MUSE model. The measured profile agrees at most radii with that of galaxies in the Byrohl et al. (2021) cosmological radiative transfer simulation at $z=3$. This suggests that the surface brightness of a Lyman-$α$ halo at $r\lesssim 100$ kpc is dominated by resonant scattering of Lyman-$α$ photons from star-forming regions in the central galaxy, whereas at $r > 100$ kpc it is dominated by photons from galaxies in surrounding dark matter halos.

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