3C 48: Stellar populations and the kinematics of stars and gas in the hostgalaxy

We present deep Keck LRIS spectroscopy of the host galaxy of 3C 48. Our obs ervations at various slit positions sample the different luminous component s near the quasar, including the apparent tidal tail to the northwest and s everal strong emission line regions. By fitting Bruzual & Chariot populatio n synthesis models to our spectra, we obtain ages for the most recent major episodes of star formation in various parts of the host galaxy covered by our slits. There is vigorous current star formation in regions just northea st and southeast of the quasar and post-starburst regions with ages up to s imilar to 10(8) yr in other parts of the host galaxy, but most of the north west tidal tail shows no sign of significant recent star formation. We use these model fits, together with the kinematics of the stars and gas, to out line a plausible evolutionary history for the host galaxy, its recent starb urst activity, the triggering of the quasar, and the interaction of the rad io jet with the ambient gas. There is strong evidence that the 3C 48 host i s an ongoing merger, and that it is probably near the peak of its starburst activity. Nevertheless, the quasar itself seems to suffer little extinctio n, perhaps because we are viewing it along a particularly favorable line of sight.