Heavily reddened type 1 quasars at z > 2-I. Evidence for significant obscured black hole growth at the highest quasar luminosities

We present a new population of z > 2 dust-reddened, type 1 quasars with 0.5 less than or similar to E (B - V) less than or similar to 1.5, selected using near-infrared (NIR) imaging data from the UKIDSS-LAS (Large Area Survey), ESO-VHS (European Southern Obseratory-VISTA Hemisphere Survey) and WISE surveys. NIR spectra obtained using the Very Large Telescope for 24 new objects bring our total sample of spectroscopically confirmed hyperluminous (>10(13) L-circle dot), high-redshift dusty quasars to 38. There is no evidence for reddened quasars having significantly different Ha equivalent widths relative to unobscured quasars. The average black hole masses (similar to 10(9)-10(10) M-circle dot) and bolometric luminosities (similar to 10(47) erg s(-1)) are comparable to the most luminous unobscured quasars at the same redshift, but with a tail extending to very high luminosities of similar to 10(48) erg s(-1). 66 per cent of the reddened quasars are detected at >3 sigma at 22 mu m by WISE. The average 6-mu m rest-frame luminosity is log(10)(L-6 mu m/ erg s(-1)) = 47.1 +/- 0.4, making the objects among the mid-infrared brightest active galactic nuclei (AGN) currently known. The extinction-corrected space density estimate now extends over three magnitudes (-30 < M-i < -27) and demonstrates that the reddened quasar luminosity function is significantly flatter than that of the unobscured quasar population at z = 2-3. At the brightest magnitudes, M-i less than or similar to -29, the space density of our dust-reddened population exceeds that of unobscured quasars. A model where the probability that a quasar becomes dust reddened increases at high luminosity is consistent with the observations and such a dependence could be explained by an increase in luminosity and extinction during AGN-fuelling phases. The properties of our obscured type 1 quasars are distinct from the heavily obscured, Compton-thick AGN that have been identified at much fainter luminosities and we conclude that they likely correspond to a brief evolutionary phase in massive galaxy formation.