Red Quasars

Pat Hall

Quasars have intrinsically blue spectra, which makes them easy to locate and study. But heavily obscured active galactic nuclei are also known to exist, in the form of radio galaxies or Seyfert 2s with broad lines seen in polarized light, for example. In between these extremes we should find a population of dust-reddened quasars. I discusss recent results on such quasars, primarily from the Sloan Digital Sky Survey. In a sample of 4576 SDSS quasars, 6% appear to be dust reddened. More than just dust reddening appears to be at work, since these quasars have narrower Balmer lines than unreddened quasars, as well as other spectral differences. Nonetheless, the color distribution of SDSS quasars contains information on the distribution of reddenings around quasars, which determines the relative contributions of unreddened, moderately reddened, and obscured quasars to the total population of luminous AGN.