Morphology and surface brightness evolution of z 1.1 radio galaxies

Roche, N., Eales, Stephen Anthony ORCID: https://orcid.org/0000-0002-7394-426X and Rawlings, S. 1998. Morphology and surface brightness evolution of z 1.1 radio galaxies. Monthly Notices of the Royal Astronomical Society 297 (2) , pp. 405-418. 10.1046/j.1365-8711.1998.01494.x

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Abstract

We use K′-band (2.1-µm) imaging to investigate the angular size and morphology of 10 6C radio galaxies, at redshifts 1≤z≤1.4. Two radio galaxies appear to be undergoing mergers, another contains, within a single envelope, two intensity peaks aligned with the radio jets, while the other seven appear consistent with being normal ellipticals in the K band. Intrinsic half-light radii are estimated from the areas of each radio galaxy image above a series of thresholds. The 6C galaxy radii are found to be significantly smaller than those of the more radio-luminous 3CR galaxies at similar redshifts. This would indicate that the higher mean K-band luminosity of the 3CR galaxies reflects a difference in the size of the host galaxies, and not solely a difference in the power of the active nuclei. The size-luminosity relation of the z∼1.1 6C galaxies indicates a 1.0–1.6 mag enhancement of their rest frame R-band surface brightness relative to either local ellipticals of the same size or FRII radio galaxies at z<0.2. The 3CR galaxies at z∼1.1 show a comparable enhancement in surface brightness. The mean radius of the 6C galaxies suggests that they evolve into ellipticals of L∼L* luminosity, and is consistent with their low-redshift counterparts being relatively small FRII galaxies ∼25 times lower in radio luminosity, or small FRI galaxies ∼1000 times lower in radio luminosity. Hence the 6C radio galaxies appear to undergo as much optical and radio evolution as the 3CR galaxies.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	galaxies: active; galaxies: evolution; galaxies: photometry; radio continuum: galaxies
Publisher:	Oxford University Press
ISSN:	0035-8711
Last Modified:	24 Oct 2022 11:13
URI:	https://orca.cardiff.ac.uk/id/eprint/47324

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