Star-forming brightest cluster galaxies at z ~ 0.4 in KiDS. Further studies of cold gas and stellar properties

Brightest cluster galaxies (BCGs) are among the most massive in Universe. Their star formation (SF) history and stellar mass assembly debated. Recent studies suggest presence of an emerging population intermediate-$z$ forming gas-rich BCGs, where molecular gas reservoirs impacted by strong environmental processing. We have selected three star-forming $z\sim0.4$ BCGs Kilo-Degree Survey (KiDS), observed them with IRAM 30m telescope first CO transitions. found double-horn CO(1$\rightarrow$0) CO(3$\rightarrow$2) emission for KiDS 1433 BCG, yielding a large reservoir $M_{H_2}=(5.9\pm1.2)\times10^{10}~M_\odot$ high gas-to-stellar ratio $M_{H_2}/M_\star=(0.32^{+0.12}_{-0.10})$. increase limited sample distant detections multiple The BCG implies low concentration, while modeling spectra yields extended reservoir, characteristic radius $\sim$(5-7) kpc, which is reminiscent mature extended-disk phase some local BCGs. For other two we able to set upper limits $M_{H_2}/M_\star<0.07$ $<0.23$, lowest then combined our observations available stellar, SF, dust properties targeted compared $\sim100$ galaxies, including additional from literature. heterogeneous. On one side, show reservoirs, sustain significant SF activity, recent infall. Conversely, existence similarly forming, but gas-poor, that depletion precedes quenching.