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The Nature of the Compact/Symmetric Near-IR Continuum Source in 4C 40.36

Research paper by E. Egami, L. Armus, G. Neugebauer, B. T. Soifer, A. S. Evans, T. W. Murphy

Indexed on: 30 Sep '99Published on: 30 Sep '99Published in: Astrophysics



Abstract

Using NICMOS on HST, we have imaged the emission-line nebulae and the line-free continuum in 4C 40.36, a ultra-steep spectrum FR II radio galaxy at z=2.269. The line-free continuum was found to be extremely compact and symmetric while the emission-line nebulae seen in H-alpha+[N II] show very clumpy structures spreading almost linearly over 16 kpc. However, this linear structure is clearly misaligned from the radio axis. The SED of the line-free continuum is very flat, suggesting that if the continuum emission is produced by a single source, it is likely to be a young bursting stellar population or scattered AGN light. However, because of the lack of a line-free optical image with a comparable spatial resolution, we cannot exclude the possibility that the observed SED is a composite of a young blue population and an old red population.