Unveiling Star Formation and its Demise in Ultra-compact Post-merger Galaxies using Jansky VLA Continuum Measurements

AGN feedback has emerged as the favored solution to the "overcooling" problem, the deficit of massive galaxies observed when compared to predictions from ΛCDM simulations. A sample of massive and compact galaxies hosting high-velocity gas outflows was found at z ≈ 0.6, estimated to have exceptionally large star formation rate (SFR) surface densities, approaching the proposed "Eddington limit" for radiation pressure on dust grains. This suggests that star formation rather than AGN feedback may be driving the observed outflows. However, these estimates suffer from significant systematic uncertainties due to large extrapolations needed to calculate SFRs with mid-IR observations, and because mid-IR emission may be extincted in these dense and dusty star forming cores. Therefore, we desired a more direct star formation tracer transparent to dust. In this poster, we present SFR estimates calculated using 1.5 GHz continuum observations taken with the VLA for 21 of these galaxies. For a majority of the sample, we estimate SFRs a factor of ∼ 2.5 smaller than those calculated from the IR. We conclude that this shift may stem from the template used to extrapolate mid-IR observations to yield a SFR assuming too cool of dust temperatures. With better estimates of these galaxies' true SFRs, we can more effectively investigate whether star formation feedback is indeed driving these outflows. We can also use this sample as an analog to understand massive galaxy evolution at z > 3, where extremely compact galaxies were more common.