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P.J. Wiita (GSU), Gopal-Krishna, V.K. Kulkarni (NCRA/TIFR), A. Osterman (GSU)
During the ``quasar era'', 1.5 < z < 3, the comoving density of radio sources was nearly 1000 times higher than it is in the local universe. Multi-wavelength observations made in the last decade strongly suggest that the star and galaxy formation activity in the universe also has dramatically declined since z ~1.5. We suggest a close physical link between these two phenomena, by arguing that during the quasar era, much of the universe was permeated by radio lobes emerging from active galaxies. Recent evidence has indicated that many radio galaxies are active for periods exceeding 108 yr, so that extremely large lobes could be produced. 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, so the actual number of sources substantially exceeds those typically estimated. When we add results from recent cosmological models that indicate that the galaxy forming material in those epochs was concentrated in filaments occupying a small fraction of the total volume, we conclude that radio lobes permeated much of the volume occupied by the protogalactic material during that era. Compression of the protostellar gas clouds by the high pressure of the plasma inside the radio lobes could thus have provided the trigger needed for the widespread, intensive star formation activity at those cosmic epochs. This mechanism can also explain the surprisingly strong magnetization of intergalactic space recently found at those early cosmic epochs.
The author(s) of this abstract have provided an email address for comments about the abstract: wiita@chara.gsu.edu