The gas that feeds early galaxies
The circumgalactic medium is the gas that sits around a galaxy, outside the disk but inside the halo that holds it. It is where galaxies get their fuel: it feeds star formation, it catches the material blown back out by winds and jets, and it regulates how much gas a galaxy has to work with. In the early universe this reservoir is cool and dense enough to glow in the Lyman alpha line, which makes it possible to see directly, as an extended halo of emission around a bright quasar.
What is not settled is what the quasar’s own jets do to that gas. Radio-loud quasars drive powerful relativistic jets straight into their surroundings, and whether that disrupts the reservoir, compresses it, or barely touches it is an open question at these redshifts. Using VLT/MUSE, I mapped the diffuse gas around 15 radio-loud quasars at 3.6 < z < 6.2, reducing the data, subtracting the quasar's own point spread function, and searching for what remains. We recovered 9 new Lyman alpha halos. Comparing their surface brightness profiles, luminosities, line widths and kinematics with halos around radio-quiet quasars at the same redshifts, extended Lyman alpha emission turns out to be more common around the radio-loud ones, which points to the jets playing a real role in the gas around them. The paper is in internal review and will be submitted soon.Lyman alpha halos around radio-loud quasars
