A Hubble Space Telescope WFPC2 Snapshot Survey of 2MASS-selected Red QSOs

Abstract

Using simple infrared color selection, the Two Micron All Sky Survey (2MASS) has found a large number of red, previously unidentified, radio-quiet quasi-stellar objects (QSOs). Although missed by UV/optical surveys, the 2MASS QSOs have Ks-band luminosities that are comparable to "classical" QSOs. This suggests the possible discovery of a previously predicted large population of dust-obscured radio-quiet QSOs. We present the results of an imaging survey of 29 2MASS QSOs observed with the Wide-Field Planetary Camera 2 on board the Hubble Space Telescope. I-band images, which benefit from the relative faintness of the nuclei at optical wavelengths, are used to characterize the host galaxies, measure the nuclear contribution to the total observed I-band emission, and survey the surrounding environments. The 2MASS QSOs are found to lie in galaxies with a variety of morphologies, luminosities, and dynamical states, not unlike those hosting radio-quiet Palomar-Green QSOs. Our analysis suggests that the extraordinary red colors of the 2MASS QSOs are caused by extinction of an otherwise typical QSO spectrum due to dust near the nucleus.