JHK' Imaging Photometry of Seyfert 1 AGNs and Quasars I: Multi-Aperture Photometry

Abstract

Near-infrared $JHK&#39;$ imaging photometry was obtained of 331 AGNs consisting mainly of Seyfert 1 AGNs and quasars (QSOs). This sample was selected to cover a range of radio emission strength, redshift from $z=0$ to 1, and absolute $B$-magnitude from $M_B=-29$ mag to -18 mag. Among low-$z$ AGNs with $z<0.3$, Seyfert $1-1.5$ AGNs are distributed over a region from a location typical of ``galaxies&#39;&#39; to a location typical of ``QSOs&#39;&#39; in the two-color $J-H$ to $H-K&#39;$ diagram, but Seyfert $1.8-2$ AGNs are distributed around the location of ``galaxies&#39;&#39;. Moreover, bright AGNs with respect to absolute $B$-magnitude are distributed near the location of ``QSOs&#39;&#39;, while faint AGNs are near the location of ``galaxies&#39;&#39;. The distribution of such low-$z$ AGNs in this diagram was found to have little dependence on their 6 cm radio flux. The near-infrared colors of the AGNs observed with an aperture of 7 pixels ($7.49&#39;&#39;$) are more QSO-like than those observed with larger apertures up to 15 pixels ($16.1&#39;&#39;$). This aperture effect may be explained by contamination from the light of host galaxies within larger apertures. This effect is more prominent for less luminous AGNs.