The 1.28 GHz MeerKAT DEEP2 Image
We present the confusion-limited 1.28 GHz MeerKAT DEEP2 image covering one $\theta_b\approx 68’$ FWHM primary-beam area with $\theta=7.6^{”}$ FWHM resolution and $\sigma_n=0.55\pm 0.01$ $\mu$Jy beam$^{-1}$ rms noise. Its J2000 center position $\alpha = 04^h 13^m 26.4^s$, $\delta = -80^\circ\ 00^\prime\ 00^{”}$ was selected to minimize artifacts caused by bright sources. We introduce the new 64-element MeerKAT array and describe commissioning observations to measure the primary-beam attenuation pattern, estimate telescope pointing errors, and pinpoint (u, v) coordinate errors caused by offsets in frequency or time. We constructed a 1.4 GHz differential source count by combining a power-law count fit to the DEEP2 confusion $P(D)$ distribution from $0.25$ to $10$ $\mu$Jy with counts of individual DEEP2 sources between 10 $\mu$Jy and 2.5 mJy. Most sources fainter than $S \sim 100$ $\mu$Jy are distant star-forming galaxies (SFGs) obeying the far-IR/radio correlation, and sources stronger than 0.25 $\mu$Jy account for $\sim 93%$ of the radio background produced by SFGs. For the first time, the DEEP2 source count has reached the depth needed to reveal the majority of the star formation history of the universe. A pure luminosity evolution of the 1.4 GHz local luminosity function consistent with the Madau & Dickinson model for the evolution of SFGs based on UV and infrared data underpredicts our 1.4 GHz source count in the range.
T Mauch, W D Cotton, J J Condon, A M Matthews et al.
The Astrophysical Journal, Volume 888, Number 2.
