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Emission lines and optical continuum in low-luminosity radio galaxies

K. A. Wills·R. Morganti·C. N. Tadhunter·T. G. Robinson·M. Villar-Martin
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Abstract

We present spectroscopic observations of a complete sub-sample of 13 low-luminosity radio galaxies selected from the 2Jy sample. The underlying continuum in these sources is carefully modelled in order to make a much-needed comparison between the emission line and continuum properties of FRIs with those of other classes of radio sources. We find that 5 galaxies in the sample show a measurable UV excess: 2 of the these sources are BL Lacs and in the remaining 3 galaxies we argue that the most likely contributor to the UV excess is a young stellar component. Excluding the BL Lacs, we therefore find that \~30% of the sample show evidence for young stars, which is similar to the results obtained for higher luminosity samples. We compare our results with far-infrared measurements in order to investigate the far-infrared-starburst link. The nature of the optical-radio correlations is investigated in light of this new available data and, in contrast to previous studies, we find that the FRI sources follow the correlations with a similar slope to that found for the FRIIs. Finally, we compare the luminosity of the emission lines in the FRI and BL Lac sources and find a significant difference in the [OIII] line luminosities of the two groups. Our results are discussed in the context of the unified schemes.

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K. A. Wills, R. Morganti, C. N. Tadhunter, T. G. Robinson, M. Villar-Martin. 2003-10-09. Emission lines and optical continuum in low-luminosity radio galaxies. https://doi.org/10.1111/j.1365-2966.2004.07195.x

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