The VLA Frontier Fields Survey: A 6GHz High-resolution Radio Survey of Abell2744

Abstract

We present 6GHz radio continuum observations of the galaxy cluster Abell 2744 ($z = 0.307$) obtained with the Karl G. Jansky Very Large Array (VLA) as part of the VLA Frontier Fields program, the goal of which is to explore the radio continuum emission from high-redshift galaxies that are magnified by foreground massive galaxy clusters. With an rms noise of $\approx 1 \mu$Jy beam$^{-1}$, in the image plane, and sub-arcsec angular resolution ($\theta_{1/2}=0.82''$), this is the deepest and most detailed radio image of Abell 2744 ever obtained. A total of 93 sources is detected with a peak signal-to-noise ratio $\geq5$, of which 46 have optical/near-infrared (IR) counterparts with available redshift, magnification ($\mu$), and stellar mass (${M}_*$) estimates. The radio sources are distributed over a redshift of 0.15 to 3.55, with a median redshift value of $z = 0.93^{+1.48}_{-0.63}$ and with a range mass from $5.5\times 10^{9} \,\rm{M}_{\odot}$ to $1.3\times 10^{11} \,\rm{M}_{\odot}$. A comparison between the radio-based star formation rates (SFRs) and those derived from ultraviolet-to-near IR data reveals that radio SFRs are typically an order of magnitude higher. This discrepancy is likely a result of strong dust obscuration affecting the UV-to-NIR tracers. We look for radio counterparts of the so-called ``Little Red Dots (LRDs)'' galaxies at $z\approx6$ seen behind Abell 2744, but find no significant detections. After stacking, we derive a 3$\sigma$ upper limit to the 6GHz radio luminosity of LRDs of $4.1\times 10^{39}\,\rm erg\,s^{-1}$. Finally, we present a sample of 22 moderately/strongly lensed galaxies ($\mu \gtrsim 2$) in the VLA Frontier Fields survey, which provides a zoomed view of the star formation processes within main sequence galaxies at $z\approx 1-2$.