Toward Accurate Modeling of Galaxy Clustering on Small Scales: Halo Model Extensions and Lingering Tension
Toward Accurate Modeling of Galaxy Clustering on Small Scales: Halo Model Extensions and Lingering Tension
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DOI：
10.3847/1538-4357/acc576
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发表时间：
2022-11
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影响因子：
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通讯作者：
G. Beltz-Mohrmann;A. O. Szewciw;A. Berlind;Manodeep Sinha
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作者：
G. Beltz-Mohrmann;A. O. Szewciw;A. Berlind;Manodeep Sinha
本文代表了对星系-晕连接提供鲁棒约束的努力，同时使用小尺度星系群集的完全数值模型测试普朗克ΛCDM宇宙学。我们探索了标准光晕占位分布模型的两个扩展：集合偏差，即光晕占位取决于光晕质量和更大的环境，以及速度偏差，即星系的速度不能完美地追踪光晕内暗物质的速度。此外，我们纳入晕质量修正，以说明重子物理对晕人口的影响。我们确定了一组最佳的聚类测量来约束SDSS DR7中低亮度和高亮度星系的“装饰”HOD模型。我们发现，对于低光度星系，同时具有装配偏差和速度偏差的模型最适合聚类测量，并且在拟合中没有张力。在这个模型中，我们分别在99%和95%的置信水平上发现了中心星系和卫星星系组合偏差的证据。此外，我们在99.9%的置信水平上发现了卫星星系速度偏差的证据。对于高光度星系，我们没有发现组合偏差或速度偏差的证据，但我们的模型与SDSS测量结果显示出明显的张力。我们发现，当我们考虑重子物理对晕质量函数的影响时，所有这些结论仍然成立，这表明我们在高亮度星系中发现的张力可能是由于我们假设的宇宙学模型的问题。
This paper represents an effort to provide robust constraints on the galaxy–halo connection and simultaneously test the Planck ΛCDM cosmology using a fully numerical model of small-scale galaxy clustering. We explore two extensions to the standard Halo Occupation Distribution model: assembly bias, whereby halo occupation depends on both halo mass and the larger environment, and velocity bias, whereby galaxy velocities do not perfectly trace the velocity of the dark matter within the halo. Moreover, we incorporate halo mass corrections to account for the impact of baryonic physics on the halo population. We identify an optimal set of clustering measurements to constrain this “decorated” HOD model for both low- and high-luminosity galaxies in SDSS DR7. We find that, for low-luminosity galaxies, a model with both assembly bias and velocity bias provides the best fit to the clustering measurements, with no tension remaining in the fit. In this model, we find evidence for both central and satellite galaxy assembly bias at the 99% and 95% confidence levels, respectively. In addition, we find evidence for satellite galaxy velocity bias at the 99.9% confidence level. For high-luminosity galaxies, we find no evidence for either assembly bias or velocity bias, but our model exhibits significant tension with SDSS measurements. We find that all of these conclusions still stand when we include the effects of baryonic physics on the halo mass function, suggesting that the tension we find for high-luminosity galaxies may be due to a problem with our assumed cosmological model.