The First Hyper-Luminous Infrared Galaxy Discovered By WISE

Abstract

We report the discovery by the Wide-field Infrared Survey Explorer (WISE) of the z = 2.452 source WISE J181417.29+341224.9, the first hyperluminous source found in the WISE survey. WISE 1814+3412 is also the prototype for an all-sky sample of similar to 1000 extremely luminous "W1W2-dropouts" (sources faint or undetected by WISE at 3.4 and 4.6 mu m and well detected at 12 or 22 mu m). The WISE data and a 350 mu m detection give a minimum bolometric luminosity of 3.7 x 10(13) L-circle dot, with similar to 10(14) L-circle dot plausible. Follow-up images reveal four nearby sources: a QSO and two Lyman break galaxies (LBGs) at z = 2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission. Gravitational lensing is unlikely given the source locations and their different spectra and colors. The dominant LBG spectrum indicates a star formation rate similar to 300 M-circle dot yr(-1), accounting for less than or similar to 10% of the bolometric luminosity. Strong 22 mu m emission relative to 350 mu m implies that warm dust contributes significantly to the luminosity, while cooler dust normally associated with starbursts is constrained by an upper limit at 1.1 mm. Radio emission is similar to 10 times above the far-infrared/radio correlation, indicating an active galactic nucleus (AGN) is present. An obscured AGN combined with starburst and evolved stellar components can account for the observations. If the black hole mass follows the local M-BH-bulge mass relation, the implied Eddington ratio is greater than or similar to 4. WISE 1814+3412 may be a heavily obscured object where the peak AGN activity occurred prior to the peak era of star formation.