卫星星系的数目与中央星系性质关系的研究

Study on the Relationship between the Number Distribution of Satellite Galaxies and the Properties of Central Galaxies

卫星星系是研究星系形成的有力探针.近期的研究指出,中央星系是椭圆星系时,其卫星星系数目比旋涡星系多.为了探究这种差异,采用了新一代流体动力学模型(The Next Generation Illustris Simulations,简称TNG模拟)中TNG300-1的数据,选择了恒星质量范围为10^(10)M⊙·h^(-1)≤Mc≤10^(12)M⊙·h^(-1)的中央星系,同时根据星系的核球质量与星系的恒星质量的比值(B/T)将这个范围的中央星系划分为旋涡星系和椭圆星系.使用统计学的方法进行分析后发现:当控制暗晕质量分布,使得不同形态的中央星系所处的暗晕的质量分布完全相同时,卫星星系分布存在新的差异,即旋涡星系的卫星星系数目更多.这一结论和观测结果相反,产生这一差异的主要原因是:旋涡星系的卫星星系包含更多的冷气体,使得旋涡星系的卫星星系恒星形成效率更高.

Satellite galaxies are powerful probes of galaxies formation.Recent studies have pointed out that when the central galaxy is an elliptical galaxy,there are more satellite galaxies than spiral galaxies.In order to explore this difference,we used the data constructed from TNG300-1 of the Next Generation Illustris Simulations set.We selected the central galaxies within 1010 M⊙·h^(-1)≤Mc≤10^(12)M⊙·h^(-1)in stellar mass.At the same time,central galaxies in this range are divided into spirals and ellipticals according to the bulge-to-total mass ratio(B/T).Through the usage of statistical methods,we found that when the mass distribution of the halos is controlled(the halo mass distribution is exactly the same between spirals and ellipticals),there is still difference in the distribution of satellite galaxies.However,the satellites of the spirals are significantly more than ellipticals.This conclusion is contrary to observations.The main reason for this difference is that the satellite galaxies of spirals contain more cold gas,which makes the satellites of spirals more efficient in star formation.