Optical--Radio Alignment in Compact Steep Spectrum Radio Sources

Session 22 - Radio - Loud AGN & Extragalactic Jets.
Display session, Wednesday, January 07
Exhibit Hall,

[22.04] Optical--Radio Alignment in Compact Steep Spectrum Radio Sources

W. H. de Vries, C. P. O'Dea, S. A. Baum (STScI), P. D. Barthel (U.Groningen (NL))

Our previous comparison of HST WFPC2 F702W images and radio maps of similar resolution of 30 3CR Compact Steep Spectrum (CSS) radio sources revealed a remarkably good alignment between the optical and radio emission (De Vries et al. 1997, ApJS, 110, 191). Unlike the alignment effect in large scale radio sources, the alignment in CSS sources is observed down to the lowest redshift in the sample (z\sim 0.1). The existing broad band data are not sufficient to distinguish between possible mechanisms for the effect, e.g., scattered nuclear light, nebular continuum, a jet-induced starburst, or emission line gas excited by the radio source. Here we present WFPC2 imaging through the linear ramp filters of restframe \ionO3 and \ionO2 line emission on a subsample of clearly aligned sources (9 galaxies, 2 quasars). By combining our HST broad and narrow band imaging with groundbased spectral information, we are able to investigate the nature of the aligned component.

Program listing for Wednesday