UVUDF: UV Luminosity Functions at the Cosmic High Noon

We present the rest-1500 angstrom UV luminosity functions (LF) for star-forming galaxies during the cosmic high noonthe peak of cosmic star formation rate at 1.5 < z < 3. We use deep NUV imaging data obtained as part of the Hubble Ultra-Violet Ultra Deep Field (UVUDF) program, along with existing deep optical and NIR coverage on the HUDF. We select F225W, F275W, and F336W dropout samples using the Lyman break technique, along with samples in the corresponding redshift ranges selected using photometric redshifts, and measure the rest-frame UV LF at z similar to 1.7, 2.2, 3.0, respectively, using the modified maximum likelihood estimator. We perform simulations to quantify the survey and sample incompleteness for the UVUDF samples to correct the effective volume calculations for the LF. We select galaxies down to M-UV = -15.9, -16.3, -16.8 and fit a faint-end slope of 1.20(-0.13)(+0.10) -1.32(-0.14)(+0.10), -1.39(-0.12)(+0.08) at 1.4 < z < 1.9, 1.8 < z < 2.6, and 2.4 < z < 3.6, respectively. We compare the star formation properties of z similar to 2 galaxies from these UV observations with results from Ha and UV + IR observations. We find a lack of high-SFR sources in the UV LF compared to the Ha and UV+ IR, likely due to dusty SFGs not being properly accounted for by the generic IRX-beta relation used to correct for dust. We compute a volume-averaged UV-to-H alpha ratio by abundance matching the rest-frame UV LF and H alpha LF. We find an increasing UV-to-H alpha ratio toward low-mass galaxies (M* less than or similar to 5 10(9) M-circle dot). We conclude that this could be due to a larger contribution from starbursting galaxies compared to the high-mass end.