Coronagraphic Imaging of 3C 273 with the Advanced Camera for Surveys

The nearby and luminous QSO 3C 273 was imaged in 2002 July with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in coronagraphic mode in F475W (g), F606W (V), and F814W (I) as part of the Early Release Observations (ERO) program. After subtraction of the remaining PSF of the QSO, these images offer the most detailed view yet of the morphology and colors of the host galaxy of this QSO. We find that the central light distribution is elongated along the jet axis and its outer edge is delineated by an arc, centered on the jet at a radius of ~26 from the QSO and bluer than the surrounding galaxy. This system is embedded in an extended galactic halo. Compared with early-type galaxies of similar redshifts and luminosities, the light distribution of 3C 273 is flatter in the core, likely from suppression by dust, but similar in the outer halo. The QSO is displaced from the isophotal center of the galaxy by ~14. Previously known emission-line extensions are confirmed and new morphological features are identified, including a dramatic spiral-shaped plume, two faint filaments, a dust lane, and a knot along the jet axis. Part of the inner jet is unambiguously detected in all three bandpasses, and its morphology matches that of a MERLIN radio map. Different mechanisms that could explain the morphology of 3C 273 are considered, such as scattered QSO radiation, a face-on disk, and a merger event.