Source Counts Spanning Eight Decades of Flux Density at 1.4 GHz
Abstract
Brightness-weighted differential source counts S2n(S) spanning the eight decades of flux density between 0.25 μJy and 25 Jy at 1.4 GHz were measured from (1) the confusion brightness distribution in the MeerKAT DEEP2 image below 10 μJy, (2) counts of DEEP2 sources between 10 μJy and 2.5 mJy, and (3) counts of NVSS sources stronger than 2.5 mJy. We present our DEEP2 catalog of 1.7 × 104 discrete sources complete above S = 10 μJy over Ω = 1.04 deg2. The brightness-weighted counts converge as S2n(S) ∝ S1/2 below S = 10 μJy, so >99% of the ΔTb ∼ 0.06 K sky brightness produced by active galactic nuclei and ≈96% of the ΔTb ∼ 0.04 K added by star-forming galaxies has been resolved into sources with S ≥ 0.25 μJy. The ΔTb ≈ 0.4 K excess brightness measured by ARCADE 2 cannot be produced by faint sources smaller than ≈50 kpc if they cluster like galaxies.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2021
- DOI:
- 10.3847/1538-4357/abdd37
- arXiv:
- arXiv:2101.07827
- Bibcode:
- 2021ApJ...909..193M
- Keywords:
-
- Galaxy evolution;
- Galaxy counts;
- Star formation;
- Radio galaxies;
- 594;
- 588;
- 1569;
- 1343;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 19 pages, 13 figures, accepted for publication in ApJ