PREPRINT
32FC69AC-4D4D-4769-B4A9-7A8809D9658D

# Source counts at 7.7 to 21 $\mu$m in CEERS field with James Webb Space Telescope

Cossas K. -W. Wu, Chih-Teng Ling, Tomotsugu Goto, Ece Kilerci, Seong Jin Kim, Tetsuya Hashimoto, Yu-Wei Lin, Po-Ya Wang, Yuri Uno, Simon C. -C. Ho, Tiger Yu-Yang Hsiao

Submitted on 5 September 2022

## Abstract

Source count -- the number density of sources as a function of flux density -- is one of the most fundamental statistics of imaging observations. One of the advantages is its simplicity, i.e., compared with more complicated and advanced analyses such as luminosity/mass functions, there is little room for analysis errors to distort results, yet the source counts still carry important information on galaxy formation and evolution. In this paper, we present these fundamental statistics for the newly advent James Webb Space Telescope (JWST) MIRI instrument. Specifically, we present source counts at the six mid-infrared bands, i.e., 7.7, 10, 12.8, 15, 18 and 21 $\mu$m. The resulting IR populations of galaxies source counts are up to $\sim$1000 times deeper than previous works, reflecting the superb sensitivity of the JWST, and agree with model predictions based on the previous generations of space infrared telescopes, except for the 7.7 $\mu$m. The deviation in 7.7 $\mu$m might come from the underestimation of flux in the previous modelling. Once the JWST collects multi-band data with photometric redshifts, more advanced analyses will allow us to disentangle the luminosity and density evolution of each population of galaxies in further detail.

## Preprint

Comment: 8 pages, 15 figures, submitted to MNRAS

Subjects: Astrophysics - Astrophysics of Galaxies; Astrophysics - Cosmology and Nongalactic Astrophysics