论文标题
使用ACT和DES：Splashback作为宇宙时钟探测大量簇中的星系演变
Probing galaxy evolution in massive clusters using ACT and DES: splashback as a cosmic clock
论文作者
论文摘要
我们在Sunyaev-Zeldovich（SZ）效应的群集中测量了星系的预计数量密度曲线以及从高级Atacama宇宙望远镜（AffACT）调查的群集中，使用黑暗能源调查（DES）观察到的星系调查（DES）。完整星系样品的飞溅半径与仅CDM模拟的理论测量一致，并且位于$ 2.4^{+0.3} _ { - 0.4} $ MPC $ H^{ - 1} $。我们根据星系颜色将样品分开，并在轮廓形状上发现显着差异。红色的星系和绿谷中的星系显示出与理论预测一致的斜率最小值，而最蓝的星系显示出较弱的特征，出现在较小的半径上。我们通过基于Infall时间将Subhalos分配到集群Halos中，将星系映射到Subhalos向Subhalos映射到Subhalos。我们发现，最陡峭的坡度的位置以及轮廓形状的差异可以映射到不同颜色星系中心的平均时间的差异。星系剖面中斜率的最小值在暗物质光环的相空间中痕迹不连续。通过将空间配置文件与不同颜色的星系中心的时间相关联，我们可以将Splashback用作时钟来了解星系淬火。我们发现，红色星系平均在其集群中以超过$ 3.2〜 \ rm的回旋$，绿色星系约为$ 2.2〜 \ rm rm $，而蓝色星系最近被积聚了，尚未达到启示剂。使用来自完整径向轮廓的信息，我们拟合了一个简单的淬火模型，并发现簇中的星系淬灭的发作发生在延迟约为GigAyear后，并且后面的Galaxies迅速淬火，以0.6 $ gyr的指数时间表为单位。
We measure the projected number density profiles of galaxies and the splashback feature in clusters selected by the Sunyaev--Zeldovich (SZ) effect from the Advanced Atacama Cosmology Telescope (AdvACT) survey using galaxies observed by the Dark Energy Survey (DES). The splashback radius for the complete galaxy sample is consistent with theoretical measurements from CDM-only simulations, and is located at $2.4^{+0.3}_{-0.4}$ Mpc $h^{-1}$. We split the sample based on galaxy color and find significant differences in the profile shapes. Red galaxies and those in the green valley show a splashback-like minimum in their slope profile consistent with theoretical predictions, while the bluest galaxies show a weak feature that appears at a smaller radius. We develop a mapping of galaxies to subhalos in $N$-body simulations by splitting subhalos based on infall time onto the cluster halos. We find that the location of the steepest slope and differences in the shapes of the profiles can be mapped to differences in the average time of infall of galaxies of different colors. The minima of the slope in the galaxy profiles trace a discontinuity in the phase space of dark matter halos. By relating spatial profiles to infall time for galaxies of different colours, we can use splashback as a clock to understand galaxy quenching. We find that red galaxies have on average been in their clusters for over $3.2 ~\rm Gyrs$, green galaxies about $2.2 ~\rm Gyrs$, while blue galaxies have been accreted most recently and have not reached apocenter. Using the information from the complete radial profiles, we fit a simple quenching model and find that the onset of galaxy quenching in clusters occurs after a delay of about a gigayear, and that galaxies quench rapidly thereafter with an exponential timescale of $0.6$ Gyr.
