| Description |
Using the WISE Preliminary Data Release mid-infrared and UKIDSS near-infrared catalogs, we have identified a sample of 0.8<z<1.5 infrared-bright galaxies with extremely large 9.7 micron silicate absorptions (virgul 5 magnitudes). These highly obscured sources present a small but not well determined fraction of the whole ULIRG population, possibly representing one the earliest stages in the transition from star formation to black hole accretion domination, before the concealing gas and dust is expelled from the galaxy. From over 1200 square degrees and 1.6 million 12-micron sources, we extracted 230 extreme silicate absorbers, increasing the sample of known extreme silicate absorption sources by more than an order of magnitude from the mere handful (virgul5) now known. We propose to obtain 70, 100, and 160 micron PACS imaging of a sub-sample of 45 for which we have spectroscopic redshifts. This will allow us to measure and characterize the peak of the infrared emission providing total bolometric luminosities and allowing a full decomposition of the contributions of hot, warm, and cool dust within these extreme sources. We will also measure their mid-infrared continuum slope, critical for an accurate measurement of the depth of the silicate absorption feature. Combined with hot dust emission, the strength of the silicate absorption will put strong constraints on the size of emitting region. |
