We examine the dust distribution around a sample of 70,000 low redshift galaxy groups and clusters derived from the Sloan Digital Sky Survey. By correlating spectroscopically identified background quasars with the galaxy groups we obtain the relative colour excess due to dust reddening. We present a significant detection of dust out to a clustercentric distance of 30 Mpc/h in all four independent SDSS colours, consistent with the expectations of weak lensing masses of similar mass halos and excess galaxy counts. The wavelength dependence of this colour excess is consistent with the expectations of a Milky Way dust law with R_V=3.1. Further, we find that the halo mass dependence of the dust content is much smaller than would be expected by a simple scaling, implying that the dust-to-gas ratio of the most massive clusters (~10E14 Msun/h) is ~3% of the local ISM value, while in small groups (~10E12.7 Msun/h) it is ~55% of the local ISM value. We also find that the dust must have a covering fraction on the order of 10% to explain the observed color differences, which means the dust is not just confined to the most massive galaxies. Comparing the dust profile with the excess galaxy profile, we find that the implied dust-to-galaxy ratio falls significantly towards the group or cluster center. This has a significant halo mass dependence, such that the more massive groups and clusters show a stronger reduction. This suggests that either dust is destroyed by thermal sputtering of the dust grains by the hot, dense gas or the intrinsic dust production is reduced in these galaxies.
Shaping the dust mass - star-formation rate relation
观测推断的尘埃质量和SDSS星系的恒星形成率（SFR）之间存在非常紧密的关系，M尘埃$\propto$ SFR $^{1.11}$（Da Cunha et al. 2010）。在这里，我们将Mdust-SFR关系扩展到高端，并表明它在非常大的SFR（即，粉尘质量低于给定SFR的预测值）。我们在图中确定了几个不同的演化过程：（1）恒星爆发阶段，在早期尘埃迅速积聚。在这个过程中可达到的最大粉尘质量是关系式弯曲的原因。要产生足够高的尘埃质量，需要有高的尘埃形成效率、底部轻的初始质量函数和可以忽略的超新星冲击尘埃破坏。(2)一个静止的恒星形成阶段，在此阶段中，尘埃质量和SFR随后平行下降，通过吸积和尘埃破坏，产生Mdust-SFR关系。沿该关系，尘气比近似恒定。我们证明了Mdust-SFR关系的幂律斜率与全局施密特-肯尼库特定律指数成反比（即，$\sim 0.9$）在简单的化学演化模型中。(3)一个淬灭阶段，导致恒星形成下降，而尘埃质量大致保持不变或按比例下降。结合合并，这些过程，以及重子总质量的范围，产生了一个复杂的人口的图表，增加了显着的分散到原来的Mdust-SFR关系。(4)在非常高的红移，人口的星系位于显着低于本地关系的预测。
