[Previous] | [Session 42] | [Next]
M. A. Osterman, P. J. Wiita, P. Barai (GSU), Gopal-Krishna (NCRA/TIFR)
Previous studies of distant radio galaxies indicate that conditions in the lobes of these galaxies could trigger massive star formation in the early universe. It is very possible that the volume filling factor of radio galaxy lobes has been dramatically underestimated so far. Radio lobes produced during the "quasar era", 1.5 < z < 3, exhibit a comoving density ~ 1000 times higher than the current level. Powerful radio galaxies are found near baryonic filament junctions in the early universe, and their radio lobes should interact with different phases of circumgalactic material. Significant amounts of star formation are very likely triggered by the lobe bow shocks and overpressured cocoons. We examine recent models of FRII radio galaxy evolution. We have successfully modeled the observed redshift-power-source size-spectral index distributions using two different models of radio galaxy evolution. We then find the total number of galaxies that possessed jet powers sufficiently high to become FRII sources for all redshifts. This number greatly exceeds those that are observed in flux limited samples because of adiabatic expansion and inverse Compton losses. This allows us to estimate the total volume occupied by the synchrotron lobes of all radio sources at a given epoch. This volume is then compared with the fraction of the relevant universe which was occupied by galaxy forming material and leads us to conclude that the fractional volume radio lobes fill can be substantial. If a substantial fraction of the relevant volume of the universe was indeed occupied by radio lobes, these lobes could play a very important role in triggering large starbursts and even galaxy formation during the quasar era. We are grateful for support from Georgia State University's Research Program Enhancement funds.
[Previous] | [Session 42] | [Next]
Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.