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Proposal Information for 2012B-0465


PI: Susan Ridgway, NOAO, ser@noao.edu
Address: PO Box 26732, 950 North Cherry Avenue, Tucson, AZ 85726-6732, USA

CoI: Mark Lacy, NRAO Headquarters
CoI: Andreea Petric, Caltech
CoI: Anna Sajina, Tufts
CoI: Tanya Urrutia, AIP, Potsdam
CoI: Duncan Farrah, Sussex

Title: The Evolution of the Obscured and Unobscured Quasar Population

Abstract: We will use GMOS-S to obtain spectra of luminous AGN and quasars selected in the mid-infrared. Mid-infrared selection is much less biased with respect to obscuration than optical and X-ray techniques, and hence allows for finding obscured (Type-2) quasars as well as Type-1 quasars. Our survey so far has been very successful and has provided an unique opportunity to construct luminosity functions for both Type-1 and Type-2 quasars selected in the same way and covering similar redshifts and luminosities. We have begun accurately quantifying the change in the obscured fraction with luminosity and redshift for the first time, and find interesting indications that at high redshift the obscured fraction rises, consistent with models for the joint formation of the galaxy and black hole populations. Our samples are, however, quite incomplete at low luminosities (and therefore high redshift), particularly in the southern hemisphere. By bringing these southern samples to a reasonable completeness level, we will greatly increase the number of high z quasars in our sample, allowing us to better judge our tantalizing initial results on the redshift evolution of the obscured fraction. In addition, these southern targets can be followed up with ALMA and GEMS/GSAOI to study the morphologies and star-formation properties of the hosts, allowing further exploration of the relationship between the formation of massive bulges and supermassive blackholes in the early universe.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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