NOAO >   Observing Info >   Approved Programs >   2006A-0303

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Proposal Information for 2006A-0303


PI: Arjun Dey, NOAO, dey@noao.edu
Address: 950 N. Cherry Ave, Tucson, AZ 85719, USA

CoI: Kate Brand, NOAO
CoI: Michael Brown, Princeton
CoI: Vandana Desai, Caltech
CoI: Emeric Le Floc'H, University of Arizona
CoI: Buell Jannuzi, NOAO
CoI: Casey Papovich, University of Arizona
CoI: Tom Soifer, Caltech
CoI: Dan Weedman, Cornell

Title: NIRI Spectroscopy of the Extreme R-[24]\ge14 Red Galaxy Population

Abstract: We have recently discovered a sample of IR-luminous objects of extreme color which may represent an early active phase in the formation of very massive galaxies. These objects are optically extremely faint (R\gtrsim 25), but nevertheless bright at mid-infrared wavelengths. Although only <1% of the mid-IR source population at bright fluxes (F_24(mu) m\gtrsim 0.8mJy), they are an increasing fraction of the source population at fainter flux densities (\gtrsim 10% at F_24(mu) m~ 0.3). \it Spitzer/IRS spectra of the brightest sources (with F_24(mu) m > 0.8mJy) suggest redshifts z~ 2. We propose to extend our study of this population to fainter mid-IR flux densities (F_24(mu) m~ 0.3) currently beyond \it Spitzer's reach. We will obtain near-IR spectra of 7 of these objects which are bright at K and with 0.3 \le F_24(mu) m < 0.8 mJy in order to determine their redshifts and investigate their spectral properties. Constraints on the redshift distribution can help determine whether or not this population is responsible for the strong evolution observed in the mid-IR number counts.


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



NOAO >   Observing Info >   Approved Programs >   2006A-0303

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