The evolution of rest-frame UV properties, Ly α EWs, and the SFR-stellar mass relation at z ∼ 2-6 for SC4K LAEs

We explore deep rest-frame UV to FIR data in the COSMOS field to measure the individual spectral energy distributions (SED) of the similar to 4000 SC4K (Sobral et al.) Lyman alpha (Ly alpha) emitters (LAEs) at z similar to 2-6. We find typical stellar masses of 10(9.3) +/- (0.6) M-circle dot and star formation rates (SFR) of SFRSED = 4.4(-2.4)(+10.5) M-circle dot yr(-1) and SFRLy alpha = 5.9(-2.6)(+6.3) M-circle dot yr(-1), combined with very blue UV slopes of beta = -2.1(-0.4)(+0.5), but with significant variations within the population. M-UV and beta are correlated in a similar way to UV-selected sources, but LAEs are consistently bluer. This suggests that LAEs are the youngest and/or most dust-poor subset of the UV-selected population. We also study the Ly alpha rest-frame equivalent width (EW0) and find 45 'extreme' LAEs with EW0 > 240 angstrom (3 sigma), implying a low number density of (7 +/- 1) x 10(-7) Mpc(-3). Overall, we measure little to no evolution of the Ly alpha EW0 and scale length parameter (w(0)), which are consistently high (EW0 = 140(-70)(+280) angstrom, w(0) = 129(-11)(+11) angstrom) from z similar to 6 to z similar to 2 and below. However, w0 is anticorrelated with M-UV and stellar mass. Our results imply that sources selected as LAEs have a high Ly alpha escape fraction (f(esc,Ly) alpha) irrespective of cosmic time, but f(esc,Ly alpha) is still higher for UV-fainter and lower mass LAEs. The least massive LAEs (<10(9.5) M-circle dot) are typically located above the star formation 'main sequence' (MS), but the offset from the MS decreases towards z similar to 6 and towards 10(10) M-circle dot. Our results imply a lack of evolution in the properties of LAEs across time and reveals the increasing overlap in properties of LAEs and UV-continuum selected galaxies as typical star-forming galaxies at high redshift effectively become LAEs.