AAS 198th Meeting, June 2001
Session 54. Galaxy Evolution and Surveys
Display, Wednesday, June 6, 2001, 10:00am-7:00pm, Exhibit Hall

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[54.06] Models for Galaxy Evolution Seen by Multiband IR Surveys

C. Xu, C.J. Lonsdale, D.L. Shupe, J. O'Linger, F. Masci (Caltech)

Empirical `backward' galaxy evolution models are developed for multiband IR surveys. A library consisting of realistic Spectral Energy Distributions (SEDs) of 837 local IR galaxies (IRAS 25\mu m selected) from the UV (1000{Å}) to the radio (20cm) is exploited to link coherently the surveys in different wavebands, under the assumption that the local correlation between SEDs and Mid-Infrared (MIR) luminosities can be applied to earlier epochs of the Universe. Assuming a \Lambda-Cosmology (\Omega\Lambda =0.7, \Omegam = 0.3), our best-fit model (`Peak Model') predicts that since z=1.5 the population of starburst galaxies undergo a strong luminosity evolution (L=L0\times (1+z)4.2) and also a strong density evolution (\rho=\rho0\times (1+z)2), the normal late-type galaxy population undergoes a passive luminosity evolution (L=L0\times (1+z)1.5), and the galaxies with AGNs undergo a luminosity evolution similar to the evolution of optical QSOs (L=L0\times (1+z)3.5). Prior at z\geq1.5 all evolution rates drop as (1+z)-3. Remarkably, this best-fit model simultaneously fits all data (both number counts and redshift distributions) obtained from all surveys examined here, including optical B band, NIR K band, ISOCAM 15\mu m, ISOPHOT 90\mu m, 175\mu m, IRAS 60\mu m, SCUBA 850\mu m, and radio continuum 20cm. Predictions for number counts, confusion limits, redshift distributions, and color-color diagrams are made for multiband surveys using future IR satellites such as SIRTF and Herschel (FIRST).

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