The Diversity of Diffuse Lyα Nebulae around Star-forming Galaxies at High Redshift
The Diversity of Diffuse Lyα Nebulae around Star-forming Galaxies at High Redshift
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DOI：
10.3847/1538-4357/837/2/172
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发表时间：
2016-11
期刊：
影响因子：
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通讯作者：
R. Xue;Kyoung-soo Lee;A. Dey;N. Reddy;Sungryong Hong;M. Prescott;H. Inami;B. Jannuzi;Anthony H.
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文献类型：
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作者：
R. Xue;Kyoung-soo Lee;A. Dey;N. Reddy;Sungryong Hong;M. Prescott;H. Inami;B. Jannuzi;Anthony H.
我们报告了在NOAO深宽视场巡天牧夫座星系中，在z = 3.78和2.66的恒星形成星系周围探测到弥漫的Lyα发射，或Lyα晕（LAH）。我们的样本由总共10000个星系组成，在两个独立的区域内，包含光谱证实的星系超密度。他们提供了一个独特的机会，调查LAH的特点如何与宿主星系的大尺度环境和物理性质的变化。我们堆叠由这些属性定义的不同样品的Lyα图像，并通过将堆叠的Lyα径向轮廓分解为紧凑的星系状和扩展的晕状分量来测量它们的LAH中值尺寸。我们发现LAH的指数尺度长度依赖于UV连续谱和Lyα光度，而不依赖于Lyα等效宽度和星系过密度参数。完整的样品主要由低紫外连续发光度的Lyα发射体（MUV <$−21）组成，LAH的大小为5-6 kpc。然而，大多数UV-或Lyα-发光的星系有更多的扩展晕，尺度长度为7-9 kpc。叠加的Lyα径向剖面比最近的理论预测下降得更陡，这些理论预测包括来自下落气体的重力冷却和卫星中低层星星形成的贡献。然而，LAH的范围与人们对星系中产生的光子的预期相匹配，然后被流出的包层中的气体共振散射。观测到的LAH大小与宿主星系性质的趋势表明，环星系介质的物理条件（覆盖分数，H i柱密度和流出速度）的变化与晕质量和/或星星形成率。
We report the detection of diffuse Lyα emission, or Lyα halos (LAHs), around star-forming galaxies at z ≈ 3.78 and 2.66 in the NOAO Deep Wide-Field Survey Boötes field. Our samples consist of a total of ∼1400 galaxies, within two separate regions containing spectroscopically confirmed galaxy overdensities. They provide a unique opportunity to investigate how the LAH characteristics vary with host galaxy large-scale environment and physical properties. We stack Lyα images of different samples defined by these properties and measure their median LAH sizes by decomposing the stacked Lyα radial profile into a compact galaxy-like and an extended halo-like component. We find that the exponential scale-length of LAHs depends on UV continuum and Lyα luminosities, but not on Lyα equivalent widths or galaxy overdensity parameters. The full samples, which are dominated by low UV-continuum luminosity Lyα emitters (MUV ≳ −21), exhibit LAH sizes of 5–6 kpc. However, the most UV- or Lyα-luminous galaxies have more extended halos with scale-lengths of 7–9 kpc. The stacked Lyα radial profiles decline more steeply than recent theoretical predictions that include the contributions from gravitational cooling of infalling gas and from low-level star formation in satellites. However, the LAH extent matches what one would expect for photons produced in the galaxy and then resonantly scattered by gas in an outflowing envelope. The observed trends of LAH sizes with host galaxy properties suggest that the physical conditions of the circumgalactic medium (covering fraction, H i column density, and outflow velocity) change with halo mass and/or star formation rates.