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Register a new userThe Local Galaxy 8 micron Luminosity Function
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J.-S. Huang SAO
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A SST survey in the NOAO Deep-Wide Field in Bootes provides a complete, 8-micron-selected sample of galaxies to a limiting (Vega) magnitude of 13.5. In the 6.88 deg$^2$ field sampled, 79% of the 4867 galaxies have spectroscopic redshifts, allowing an accurate determination of the local (z<0.3) galaxy luminosity function. Stellar and dust emission can be separated on the basis of observed galaxy colors. Dust emission (mostly PAH) accounts for 80% of the 8 micron luminosity, stellar photospheres account for 19%, and AGN emission accounts for roughly 1 %. A sub-sample of the 8 micron-selected galaxies have blue, early-type colors, but even most of these have significant PAH emission. The luminosity functions for the total 8 micron luminosity and for the dust emission alone are both well fit by Schechter functions. For the 8 micron luminosity function, the characteristic luminosity is u L_{ u}^*(8.0 micron) = 1.8 times 10^{10}$ Lsun while for the dust emission alone it is 1.6 x 10^{10}$ Lsun ull. The average 8 micron luminosity density at z<0.3 is 3.1 x 10^7 Lsun Mpc^{-3}, and the average luminosity density from dust alone is 2.5 x 10^7 Lsun Mpc^{-3}. This luminos ity arises predominantly from galaxies with 8 micron luminosities ($ u L_{ u}$) between $2times 10^9$ and $2 x 10^{10}$ Lsun, i.e., normal galaxies, not LIRGs or ULIRGs.
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