Data from: GAMA + KiDS: empirical correlations between halo mass and other galaxy properties near the knee of the stellar-to-halo mass relation

We use KiDS weak lensing data to measure variations in mean halo mass as a function of several key galaxy properties (namely stellar colour, specific star formation rate, Sérsic index, and effective radius) for a volume-limited sample of GAMA galaxies in a narrow stellar mass range [M∗ ∼(2-5) × 1010 M⊙]. This mass range is particularly interesting, inasmuch as it is where bimodalities in galaxy properties are most pronounced, and near to the break in both the galaxy stellar mass function and the stellar-to-halo mass relation (SHMR). In this narrow mass range, we find that both size and Sérsic index are better predictors of halo mass than either colour or SSFR, with the data showing a slight preference for Sérsic index. In other words, we find that mean halo mass is more tightly correlated with galaxy structure than either past star formation history or current star formation rate. Our results lead to an approximate lower bound on the dispersion in halo masses among log M∗ ≈ 10.5 galaxies: We find that the dispersion is ≳ 0.3 dex. This would imply either that offsets from the mean SHMR are closely coupled to size/structure or that the dispersion in the SHMR is larger than what past results have suggested. Our results thus provide new empirical constraints on the relationship between stellar and halo mass assembly at this particularly interesting mass range.

我们使用千度巡天（KiDS）弱引力透镜数据，针对窄恒星质量范围[M*约为(2~5)×10^10 M⊙]内的体积限制GAMA星系样本，测量平均晕质量随若干关键星系属性的变化，这些属性包括恒星颜色、比恒星形成率（specific star formation rate，SSFR）、塞斯克（Sérsic）指数以及有效半径。该恒星质量范围极具研究价值：一方面星系属性的双峰分布在此处最为显著，另一方面该范围邻近星系恒星质量函数与恒星-晕质量关系（SHMR）的拐点。在该窄质量范围内，我们发现相较于恒星颜色与SSFR，星系有效半径与塞斯克指数对晕质量的预测能力更强，且数据略微偏向于以塞斯克指数作为最优预测因子。换言之，平均晕质量与星系结构的相关性，要紧密于其与星系过去的恒星形成历史或当前恒星形成率的相关性。我们的研究结果为log M*≈10.5的星系样本的晕质量弥散给出了近似下限：该弥散值不小于0.3 dex。这意味着两种可能性：一是与恒星-晕质量关系平均值的偏移量与星系有效半径/结构紧密相关，二是恒星-晕质量关系的弥散程度大于过往研究结果的推断值。因此，我们的研究结果为该极具研究价值的质量范围内的恒星与晕质量形成演化关系提供了全新的经验约束。