Previous abstract Next abstract
We analyze low-dispersion optical spectra (5000-10000 \AA ), from the Isaac Newton Telescope with faint-object spectrograph, for six candidate hotspots in radio galaxies and quasars. Each is tested against template power-law, galaxy, and in some cases stellar spectra via $\chi^2$ minimization. We confirm that the hot spot in 3C 303 shows a featureless power-law continuum. The tentative hotspot identification in the northeast lobe of 3C 319 is in fact a galaxy in the surrounding cluster. The hotspot candidate in 3C 330 is sufficiently diffuse that we have no useful detection. One candidate object near the north hot spot of 3C 390.3 appears to be a superimposed star.
The very red hot-spot candidate near 3C 247 is better fit by a truncated power-law synchrotron form than a star; we would have clearly detected molecular absorption features from any star matching its measured (V-K) color. We also present coronagraphic observations of the spectrum of the 3C 273 jet and the hot spot at its tip; it does not appear that the jet color reddens as strongly along the jet as has been reported.
Our data also include the nuclei of the central galaxies; we report 4000-\AA\ break amplitudes for several objects to $z=0.75$, and measure emission lines as far red as [S II] $\lambda \lambda 6717,6731$ for 3C 330 at $z=0.55$.
This research was conducted as part of an NSF Research Experiences for Undergraduates program under grant AST-9300413.
Monday program listing