Lyman Break Galaxies and the Lyα Forest
Lyman Break Galaxies and the Lyα Forest
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DOI：
10.1086/376789
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发表时间：
2002-09
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影响因子：
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通讯作者：
J. Kollmeier;D. Weinberg;R. Davé;N. Katz
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作者：
J. Kollmeier;D. Weinberg;R. Davé;N. Katz
我们使用流体动力学宇宙学模拟来预测Lyα森林吸收与星系红移z≈3的分布之间的相关性。Lyα通量衰减的概率分布函数（PDF）在星系附近系统地向更高的值移动，反映了这些星系所处的过度密集的环境。在50-200 km s-1的平滑光谱中，预测的信号仍然很强，可以用中等分辨率的类星体光谱进行测试。高红移星系对高密度区域的强烈偏倚在通量PDF上留下了清晰的印记，但预测对星系重子质量或恒星形成速率并不敏感，它们对星系和暗物质晕的预测是相似的。通量PDF对星系接近度的依赖对红移测定误差很敏感，均方根误差在150-300 km s-1之间，大大削弱了预测趋势。在更大的尺度上，5或10 h-1 Mpc立方体内的平均星系过密度与穿过立方体中心的视线上的平均Lyα通量衰减密切相关。由于星系偏差，星系的相关斜率是暗物质的3倍。预测的大尺度相关性与最近报道的观测结果在定性上一致。然而，观测也显示了星系附近的平均吸收量下降，即使我们允许星系或其中的活动星系核成为电离源，我们的模型也无法预测这一点。这种减少的吸收可能是星系对周围星系间介质反馈的标志，可能是通过星系风。我们发现，一个简化的“风”模型消除了星系周围球体中的中性氢，可以在一定程度上解释这些数据。然而，由于特殊的速度允许远距离的气体在星系红移时产生饱和吸收，这些风（或任何其他反馈机制）必须扩展到~1.5 h- 1mpc的共同运动半径才能重现观测结果。我们还讨论了目标星系的延伸Lyα发射在小角距离处“填补”预期Lyα森林吸收的可能性。
We use hydrodynamic cosmological simulations to predict correlations between Lyα forest absorption and the galaxy distribution at redshift z ≈ 3. The probability distribution function (PDF) of Lyα flux decrements shifts systematically toward higher values in the vicinity of galaxies, reflecting the overdense environments in which these galaxies reside. The predicted signal remains strong in spectra smoothed over 50-200 km s-1, allowing tests with moderate-resolution quasar spectra. The strong bias of high-redshift galaxies toward high-density regions imprints a clear signature on the flux PDF, but the predictions are not sensitive to galaxy baryon mass or star formation rate, and they are similar for galaxies and dark matter halos. The dependence of the flux PDF on galaxy proximity is sensitive to redshift determination errors, with rms errors of 150-300 km s-1 substantially weakening the predicted trends. On larger scales, the mean galaxy overdensity in a cube of 5 or 10 h-1 Mpc (comoving) is strongly correlated with the mean Lyα flux decrement on a line of sight through the cube center. The slope of the correlation is ~3 times steeper for galaxies than for dark matter as a result of galaxy bias. The predicted large-scale correlation is in qualitative agreement with recently reported observational results. However, observations also show a drop in the average absorption in the immediate vicinity of galaxies, which our models do not predict even if we allow the galaxies or active galactic nuclei within them to be ionizing sources. This decreased absorption could be a signature of galaxy feedback on the surrounding intergalactic medium, perhaps via galactic winds. We find that a simplified "wind" model that eliminates neutral hydrogen in spheres around the galaxies can marginally explain the data. However, because peculiar velocities allow gas at large distances to produce saturated absorption at the galaxy redshift, these winds (or any other feedback mechanism) must extend to comoving radii of ~1.5 h-1 Mpc to reproduce the observations. We also discuss the possibility that extended Lyα emission from the target galaxies "fills in" the expected Lyα forest absorption at small angular separations.