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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 606550.0, MPI für Astronomie / Publikationen_mpia
Probing the faint end of the quasar luminosity function at z~ 4 in the COSMOS field
Authors:Ikeda, H.; Nagao, T.; Matsuoka, K.; Taniguchi, Y.; Shioya, Y.; Trump, J. R.; Capak, P.; Comastri, A.; Enoki, M.; Ideue, Y.; Kakazu, Y.; Koekemoer, A. M.; Morokuma, T.; Murayama, T.; Saito, T.; Salvato, M.; Schinnerer, E.; Scoville, N. Z.; Silverman, J. D.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:The Astrophysical Journal Letters
Issue / Number:2
Audience:Not Specified
Abstract / Description:We searched for quasars that are ~3 mag fainter than the SDSS quasars in the redshift range 3.7 <~ z <~ 4.7 in the COSMOS field to constrain the faint end of the quasar luminosity function (QLF). Using optical photometric data, we selected 31 quasar candidates with 22 < i' < 24 at z ~ 4. We obtained optical spectra for most of these candidates using FOCAS on the Subaru telescope and identified eight low-luminosity quasars at z ~ 4. In order to derive the QLF based on our spectroscopic follow-up campaign, we estimated the photometric completeness of our quasar survey through detailed Monte Carlo simulations. Our QLF at z ~ 4 has a much shallower faint-end slope (β = -1.67+0.11 -0.17) than that obtained by other recent surveys in the same redshift. Our result is consistent with the scenario of downsizing evolution of active galactic nuclei inferred by recent optical and X-ray quasar surveys at lower redshifts.
Free Keywords:cosmology: observations; quasars: general; surveys
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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