Was the cosmic web of protogalactic material permeated by lobes of radio galaxies during the quasar era?

Abstract

Evidence for extended active lifetimes (>10⁸ yr) for radio galaxies implies that many large radio lobes were produced during the "quasar era," 1.5 < z < 3, when the comoving density of radio sources was 2-3 dex higher than the present level. However, both adiabatic and inverse Compton losses against the intense microwave background substantially reduce the ages and numbers of sources that are detected in flux-limited surveys. The realization that the galaxy-forming material in those epochs was concentrated in filaments occupying a small fraction of the total volume then leads to the conclusion that radio lobes permeated much of the volume occupied by the protogalactic material during that era. The sustained overpressure in these extended lobes may have played an important role in triggering the high inferred rate of star formation at z > 1.5 and in the magnetization of the cosmic network of filaments.