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Title: The 3CR radio galaxies at redshift z ˜ 1
Author: Best, P. N.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1997
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Hubble Space Telescope (HST) observations are presented for a sample of 28 3CR radio galaxies in the redshift range 0.6 < z < 1.8, together with maps of their radio structure at comparable angular resolution obtained using the VLA interferometer, and infrared images of the field taken with UKIRT. The HST images display a wide range of bizarre structures which tend to be aligned along the radio axis. The morphology of the optical emission evolves strongly with the physical size of the radio source, suggesting that the predominant cause of the optical alignment is a massive burst of star formation induced by shocks associated with the passage of the radio hotspots through the host galaxy. Such a starburst would evolve and fade throughout the lifetime of the radio source. This model is supported by the HST observations of 3C34, which provide evidence for such a burst of star formation having been induced in a companion galaxy by the impact of the radio jet. In contrast, the infrared images show giant elliptical galaxies. The radial intensity profiles of the galaxies are well-matched at radii ≤ 30 kpc by a de Vaucouleur's law, whilst at greater radii they show an excess of emission similar to that of cD galaxy halos. Their infrared K-magnitudes are tightly correlated with redshift, consistent with them being a passively evolving population of galaxies which formed at high redshift. Passive evolution of their stellar populations is also required if their surface brightness vs characteristic size relation is to match the fundamental plane defined by low redshift giant elliptical galaxies. The implications of these results for the formation and evolution of massive galaxies and for the cosmic evolution of the radio source population are discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available