The Nature of XBONGs and Optically Elusive AGN

Sample images from the VLA of pointlike, jetlike, and ringlike radio morphology at 1'' resolution.

Using near-IR spectra from NASA's IRTF in Hawaii, we tested whether accepted diagnostic emission line ratios were successful in selecting X-ray Bright Optically Normal Galaxies (XBONGs), which are missed in optical surveys and lead to incomplete samples. We also tested a wide variety of other AGN selection techniques on our XBONG sample, including mid-IR photometric algorithms and the presence of coronal emission lines. We also modelled our NIR spectral continua as a combination of a stellar blackbody and a population of dust near the sublimation temperature, to ascertain the importance of circumnuclear dust in causing the optical obscuration.