Σ(SFR)/M- redshift relation for clusters (black symbols) and groups (magenta symbols). Square symbols, triangles, and dots identify, respectively, the COSMOS composite systems, the GOODS systems, and the remaining systems. The red star identifies the Bullet cluster. The black solid line shows the best fit Σ(SFR)/M – z relation for the cluster sample, excluding the Bullet cluster. The relation fitted to the data is of the type Σ(SFR)/M  ∝ z^α. The dashed line shows the relation, Σ(SFR)/M  ∝ (1 + z)^α, of Bai et al. (2009) rescaled to the LIRG L_IR-regime and to the r₂₀₀ region. The magenta solid line shows the best fit for the sample of groups and poor clusters.