# A closer look at the deep radio sky: Multi-component radio sources at 3-GHz VLA-COSMOS

## TL;DR

This paper characterizes multi-component radio sources at 3 GHz in the COSMOS field, revealing new detections, detailed morphologies, and host galaxy properties, enhancing understanding of radio source structures and their galaxy environments.

## Contribution

It provides a detailed classification and analysis of multi-component radio sources at 3 GHz, including new detections and morphological insights enabled by high-resolution imaging.

## Key findings

- Identified 67 multi-component radio sources, including 8 new detections at 3 GHz.
- Resolved multiple emission peaks in 28 extended sources not seen at 1.4 GHz.
- Most multi-component sources are in massive galaxies and many AGN show disturbed or bent morphologies.

## Abstract

In this data paper we present and characterise the multi-component radio sources identified in the VLA-COSMOS Large Project at 3 GHz (0.75 arcsec resolution, 2.3 {\mu}Jy/beam rms), i.e. the radio sources which are composed of two or more radio blobs.The classification of objects into multi-components was done by visual inspection of 351 of the brightest and most extended blobs from a sample of 10,899 blobs identified by the automatic code blobcat. For that purpose we used multi-wavelength information of the field, such as the 1.4-GHz VLA-COSMOS data and the UltraVISTA stacked mosaic available for COSMOS. We have identified 67 multi-component radio sources at 3 GHz: 58 sources with AGN powered radio emission and 9 star-forming galaxies. We report 8 new detections that were not observed by the VLA-COSMOS Large Project at 1.4 GHz, due to the slightly larger area coverage at 3 GHz. The increased spatial resolution of 0.75 arcsec has allowed us to resolve (and isolate) multiple emission peaks of 28 extended radio sources not identified in the 1.4-GHz VLA-COSMOS map. We report the multi-frequency flux densities (324 MHz, 325 MHz, 1.4 GHz & 3 GHz), star-formation-rates, and stellar masses of these objects. Multi-component objects at 3-GHz VLA-COSMOS inhabit mainly massive galaxies (>10^10.5 Msun). The majority of the multi-component AGN lie below the main-sequence of star-forming galaxies (SFGs), in the green valley and the quiescent region. We provide detailed description of the objects: amongst the AGN there are 2 head-tail, 10 core-lobe, 9 wide-angle-tail (WAT), 8 double-double or Z-/X-shaped, 3 bent-tail radio sources, and 26 symmetric sources, while amongst the SFGs we find the only star-forming ring seen in radio emission in COSMOS. We report a large number (32/58) of disturbed/bent multi-component AGN, 18 of which do not lie within X-ray groups in COSMOS (0.08 < z < 1.53). [abridged]