James Webb Space Telescope Feed Post


EarlyReleases
Date: 9/28/2023

PEARLS: JWST counterparts of micro-Jy radio sources in the Time Domain Field


Wider-field images of ID 193. The radio image is on the left, and the other panels show two NIRCam images as labeled. Field of view is 16'' in all panels. Ellipses show positions and sizes of four radio sources, the southern two of which are outside the NIRCam coverage. The ID 194 nucleus is saturated in the original NIRCam data and therefore appears black. Abstract: The Time Domain Field (TDF) near the North Ecliptic Pole in JWST's continuous-viewing zone will become a premier "blank field" for extragalactic science. JWST/NIRCam data in a 16 arcmin2 portion of the TDF identify 4.4 µm counterparts for 62 of 63 3 GHz sources with S(3 GHz) > 5 {\mu}Jy. The one unidentified radio source may be a lobe of a nearby Seyfert galaxy, or it may be an infrared-faint radio source. The bulk properties of the radio-host galaxies are consistent with those found by previous work: redshifts range from 0.14 to 4.4 with a median redshift of 1.33. The radio emission arises primarily from star formation in ~2/3 of the sample and from an active galactic nucleus in ~1/3, but just over half the sample shows evidence for an AGN either in the spectral energy distribution or by radio excess. All but three counterparts are brighter than magnitude 23 AB at 4.4 µm, and the exquisite resolution of JWST identifies correct counterparts for sources for which observations with lower angular resolution would mis-identify a nearby bright source as the counterpart when the correct one is faint and red. Up to 11% of counterparts might have been unidentified or misidentified absent NIRCam observations.