moss ii : mid-frequency radio catalogue of the Saraswati core region

ABSTRACT The MeerKAT Observations of the Saraswati Supercluster is an ongoing project attempting to study the radio and optical properties of the core region of the Saraswati supercluster which will eventually entail a full survey of the entire supercluster region. We have used MeerKAT L-band (1.28 GHz) images at an angular resolution of $8\,\rm arcsec$ from previous deep (central RMS noise of $11\text{-}16 \:\mu$Jy beam$^{-1}$) pilot observations of the core region ($z \sim 0.28$) of the Saraswati supercluster containing the two most massive galaxy clusters: Abell 2631 and ZwCl2341. These cluster fields cover an area of ${\sim} 1.6$ deg$^{2}$ and the radio catalogues produced from each cluster region contain 1999 and 2611 sources ($5 \sigma$ limit) for Abell 2631 and ZwCL2341, respectively. For each catalogue, we investigated the noise properties, astrometry, flux density scale accuracy, spectral properties, etc. of the radio sources. The catalogues were then corrected for various observational biases before derivation of the radio source counts. In agreement with previous studies, we find that at the sub-mJy level our counts show the characteristic flattening, indicating the increased dominance of the star-forming galaxy (SFG) population over the active galactic nuclei (AGN). Furthermore, in this sub-mJy regime the counts lie slightly higher (a ‘bump’ feature) compared to other deep MeerKAT data and recent radio-sky simulations. We suggest that this feature could be attributed to an enhanced population of intermediate SFG and/or AGNs associated with these galaxy cluster fields. In addition cosmic variance could represent an important source of uncertainty in the source counts.