We investigate the relationship between faint X-ray and 1.4 GHz radio source populations detected within 3 \arcmin of the Hubble Deep Field North using the 1 Ms Chandra and 40 \mu Jy VLA surveys .
Within this region , we find that \approx 42 % of the 62 X-ray sources have radio counterparts and \approx 71 % of the 28 radio sources have X-ray counterparts ; thus a 40 \mu Jy VLA survey at 1.4 GHz appears to be well-matched to a 1 Ms Chandra observation .
Among the different source populations sampled , we find that the majority of the 18 X-ray detected emission-line galaxies ( ELGs ) have radio and mid-infrared ISOCAM counterparts and appear to be luminous star-forming galaxies at z = 0.3 –1.3 .
Importantly , the radio-detected ELGs make up \approx 35 % of the X-ray source population at 0.5–8.0 keV X-ray fluxes between \approx ( 1 – 5 ) \times 10 ^ { -16 } erg cm ^ { -2 } s ^ { -1 } and signal the emergence of the luminous , high- z starburst galaxy population in the X-ray band .
We find that the locally-determined correlation between X-ray luminosities and 1.4 GHz radio luminosity densities of the late-type galaxies can easily be extended to include the luminous intermediate-redshift ELGs , suggesting that the X-ray and radio emission processes are generally associated in star-forming galaxies .
This result implies that the X-ray emission can be used as an indicator of star formation rate for star-forming galaxies .
Finally , we show that there appear to be two statistically distinct types of ISOCAM -detected star-forming galaxies : those with detectable radio and X-ray emission and those without .
The latter type may have stronger mid-infrared emission-line features that increase their detectability at mid-infrared wavelengths .