| Description: | The cold circumgalactic medium is an elusive but critical component in the evolution of distant galaxies. In a cosmic tale of Spiderwebs, Anthills, and Dragonflies, I will present what we learned about the cold molecular gas on large scales around some of the most massive systems in the Universe, namely powerful radio galaxies and quasars. By pushing interferometers to low resolution, we reached the surface-brightness sensitivity to image the cold CGM on ~100 kpc scale and capture a variety of evolutionary processes, from molecular halo gas that fuels in-situ star formation across the Spiderweb galaxy, to cold-stream accretion that drives the evolution of the Anthill galaxy. Recent discoveries also suggest that molecular gas is particularly widespread around some radio-loud systems, and that radio sources can brighten up in the presence of molecular gas in the environment, thus indicating an interplay between the radio source and its cold environment. If widespread molecular gas, and associated cooling and accretion processes, are common around distant galaxies, then this will require us to revise our ideas about how galaxies are formed. The upcoming era of ALMA Band 1 and later the Next-Generation VLA will offer exciting possibilities for studying the cold molecular medium across the Early Universe. I will conclude this talk with a brief overview of the telescopes and CASA data processing software that will make this happen. |
