The Rest-frame Optical (900nm) Galaxy Luminosity Function at z ∼ 4-7: Abundance Matching Points to Limited Evolution in the MSTAR/MHALO Ratio at z ≥ 4

We present the first determination of the galaxy luminosity function (LF) at z similar to 4, 5, 6, and 7, in the rest-frame optical at lambda(rest) similar to 900 nm (z' band). The rest-frame optical light traces the content in low-mass evolved stars (similar to stellar mass-M*), minimizing potential measurement biases for M*. Moreover, it is less affected by nebular line emission contamination and dust attenuation, is independent of stellar population models, and can be probed up to z similar to 8 through Spitzer/IRAC. Our analysis leverages the unique full-depth Spitzer/IRAC 3.6-8.0 mu m data over the CANDELS/GOODS-N, CANDELS/GOODS-S, and COSMOS/UltraVISTA fields. We find that, at absolute magnitudes where M-z' is fainter than greater than or similar to-23 mag, M-z' linearly correlates with M-UV,M-1600. At brighter M-z', MUV, 1600 presents a turnover, suggesting that the stellar mass-to-light ratio M*/L-UV,L-1600 could be characterized by a very broad range of values at high stellar masses. Median-stacking analyses recover an M*/L-z' roughly independent on M-z' for M-z' greater than or similar to -23 mag, but exponentially increasing at brighter magnitudes. We find that the evolution of the LF marginally prefers a pure luminosity evolution over a pure density evolution, with the characteristic luminosity decreasing by a factor of similar to 5x between z. similar to 4 and z. similar to 7. Direct application of the recovered M*/L-z' generates stellar mass functions consistent with average measurements from the literature. Measurements of the stellar-to-halo mass ratio at fixed cumulative number density show that it is roughly constant with redshift for M-h greater than or similar to 10(12)M(circle dot). This is also supported by the fact that the evolution of the LF at 4 less than or similar to z less than or similar to 7 can be accounted for by a rigid displacement in luminosity, corresponding to the evolution of the halo mass from abundance matching.