We use a simple optical/infrared photometric selection of high redshift QSOs which identifies a Lyman Break in the optical and requires a red IRAC color to distinguish QSOs from common interlopers. We find 100 U-dropout (z=3) QSO candidates with r'<22 within 11.2 deg^2 in the ELAIS-N1 & ELAIS-N2 fields in the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Legacy Survey. Spectroscopy of 10 candidates shows that they are all QSOs with 2.83<z<3.44. We use detailed simulations which incorporate variations in QSO SEDs, IGM transmission and imaging depth to derive a completeness of 85-90% between 3.0<z<3.4. The resulting luminosity function is two magnitudes fainter than SDSS and, when combined with those data, gives a faint end slop \beta = 1.62 \pm 0.18, consistent with measurements at z<2 and steeper than initial measurements at the same redshift.
@article{arxiv.astro-ph/0604373,
title = {The z=3 QSO Luminosity Function with SWIRE},
author = {B. Siana and M. Polletta and H. E. Smith and C. J. Lonsdale and E. Gonzalez-Solares and D. Farrah and T. S. R. Babbedge and M. Rowan-Robinson and J. Surace and D. Shupe and F. Fang},
journal= {arXiv preprint arXiv:astro-ph/0604373},
year = {2007}
}
Comments
4 pages, 2 color figures. To appear in the proceedings for the Spitzer Science Center 2005 Conference: Infrared Diagnostics of Galaxy Evolution, Ed. R. Chary. November, 2005, Pasadena