Near-Infrared Observations of Extended Emission around PG 1545+210

Abstract

Infrared images at H and Ks of the quasar PG 1545+210 clearly show both extended emission centered on the quasar and a companion galaxy. The magnitudes of the extended emission deduced from these observations depend strongly on the model adopted for the emission. Both an exponential disk model and a de Vaucouleurs model provide adequate fits to the extended emission. If it is assumed to follow an exponential disk galaxy, these measurements imply that the host galaxy has absolute magnitudes comparable with those of a Schechter L^* galaxy. With this assumption for the intrinsic light distribution, the H magnitude and the Hubble Space Telescope limit on the V magnitude are inconsistent with color predictions for unreddened spiral galaxies at the redshift of the quasar. If the data are fitted to a de Vaucouleurs model, the extended emission dominates the total energy of the system and significantly exceeds that of an L^* galaxy. The companion galaxy has colors consistent with its being at the redshift of the quasar, but its luminosity is at most a small part of that of the entire system. If the companion is at the redshift of PG 1545+210, its absolute magnitude is M_H ∼ -22 mag, significantly fainter than that of an L^* galaxy.

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