We present the rest-frame V -band luminosity function ( LF ) of galaxies at 0.4 \leq z < 4.0 , measured from a near-infrared selected sample constructed from the NMBS , the FIRES , the FIREWORKS , and the ultra-deep NICMOS and WFC3 observations in the HDFN , HUDF , and GOODS-CDFS , all having high-quality optical to mid-infrared data .
This unique sample combines data from surveys with a large range of depths and areas in a self-consistent way , allowing us to ( 1 ) minimize the uncertainties due to cosmic variance ; and ( 2 ) simultaneously constrain the bright and faint ends with unprecedented accuracy over the targeted redshift range , probing the LF down to 0.1 ~ { } L ^ { \star } at z \sim 3.9 .
We find that ( 1 ) the faint end is fairly flat and with a constant slope from z = 4 , with \alpha = -1.27 \pm 0.05 ; ( 2 ) the characteristic magnitude has dimmed by 1.3 mag from z \sim 3.7 to z = 0.1 ; ( 3 ) the characteristic density has increased by a factor of \sim 8 from z \sim 3.7 to z = 0.1 , with 50 % of this increase from z \sim 4 to z \sim 1.8 ; and ( 4 ) the luminosity density peaks at z \approx 1 - 1.5 , increasing by a factor of \sim 4 from z = 4.0 to z \approx 1 - 1.5 , and subsequently decreasing by a factor of \sim 1.5 by z = 0.1 .
We find no evidence for a steepening of the faint-end slope with redshift out to z = 4 , in contrast with previous observational claims and theoretical predictions .
The constant faint-end slope suggests that the efficiency of stellar feedback may evolve with redshift .
Alternative interpretations are discussed , such as different masses of the halos hosting faint galaxies at low and high redshifts and/or environmental effects .