Mid-Infrared Galaxy Luminosity Functions from the AGN and Galaxy Evolution Survey

Citation:

Dai X, Assef RJ, Kochanek CS, Brodwin M, Brown MJI, Caldwell N, Cool RJ, Dey A, Eisenhardt P, Eisenstein D, et al. Mid-Infrared Galaxy Luminosity Functions from the AGN and Galaxy Evolution Survey. The Astrophysical Journal. 2009;697 :506-521.

Date Published:

May 1, 2009

Abstract:

We present galaxy luminosity functions at 3.6, 4.5, 5.8, and 8.0 μmmeasured by combining photometry from the IRAC Shallow Survey withredshifts from the AGN and Galaxy Evolution Survey (AGES) of the NOAODeep Wide-Field Survey Boötes field. The well defined IRAC samplescontain 3800-5800 galaxies for the 3.6-8.0 μm bands withspectroscopic redshifts and z < 0.6. We obtained relatively completeluminosity functions in the local redshift bin of z < 0.2 for allfour IRAC channels that are well fitted by Schechter functions. Afteranalyzing the samples for the whole redshift range, we found significantevolution in the luminosity functions for all four IRAC channels thatcan be fitted as an evolution in M * with redshift, ΔM* = Qz. While we measured Q = 1.2 ± 0.4 and 1.1± 0.4 in the 3.6 and 4.5 μm bands consistent with thepredictions from a passively evolving population, we obtained Q = 1.8± 1.1 in the 8.0 μm band consistent with other evolving starformation rate estimates. We compared our luminosity functions with thepredictions of semianalytical galaxy formation and found the bestagreement at 3.6 and 4.5 μm, rough agreement at 8.0 μm, and alarge mismatch at 5.8 μm. These models also predicted a comparableQ-value to our luminosity functions at 8.0 μm, but predicted smallervalues at 3.6 and 4.5 μm. We also measured the luminosity functionsseparately for early- and late-type galaxies. While the luminosityfunctions of late-type galaxies resemble those for the total population,the luminosity functions of early-type galaxies in the 3.6 and 4.5 μmbands indicate deviations from the passive evolution model, especiallyfrom the measured flat luminosity density evolution. Combining ourestimates with other measurements in the literature, we found 53

Notes:

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