Source Counts Spanning Eight Decades of Flux Density at 1.4 GHz

Abstract

Brightness-weighted differential source counts S 2 n ( S ) spanning the eight decades of flux density between 0.25 μ Jy and 25 Jy at 1.4 GHz were measured from (1) the confusion brightness distribution in the MeerKAT DEEP2 image below 10 μ Jy, (2) counts of DEEP2 sources between 10 μ Jy and 2.5 mJy, and (3) counts of NVSS sources stronger than 2.5 mJy. We present our DEEP2 catalog of 1.7 × 10 4 discrete sources complete above S = 10 μ Jy over Ω = 1.04 deg 2 . The brightness-weighted counts converge as S 2 n ( S ) ∝ S 1/2 below S = 10 μ Jy, so >99% of the Δ T b ∼ 0.06 K sky brightness produced by active galactic nuclei and ≈96% of the Δ T b ∼ 0.04 K added by star-forming galaxies has been resolved into sources with S ≥ 0.25 μ Jy. The Δ T b ≈ 0.4 K excess brightness measured by ARCADE 2 cannot be produced by faint sources smaller than ≈50 kpc if they cluster like galaxies.