We present sensitive phase-referenced VLBI results on the radio continuum emission from the z = 4.7 double source BRI 1202–0725 .
The observations were carried out at 1425 MHz using the Very Long Baseline Array ( VLBA ) , the phased Very Large Array ( VLA ) , and the Green Bank Telescope ( GBT ) .

Our sensitive VLBI images of BRI 1202–0725 at 0.25 \times 0.14 arcsec resolution show a continuum structure in each of its two components .
Fitting Gaussian models to these continuum structures yield total flux densities of 315 \pm 38 and 250 \pm 39 ~ { } \mu Jy , for the northern and the southern components , respectively .
The estimated intrinsic brightness temperatures of these continuum structures are \sim 2 \times 10 ^ { 4 } K. Neither component is detected at the full VLBI resolution ( 29 mas \times 7 mas ) , with a 4 \sigma point source upper limit of 40 \mu Jy beam ^ { -1 } , or an upper limit to the intrinsic brightness temperature of 6.7 \times 10 ^ { 5 } K. The highest angular resolution with at least a 4 \sigma detection is \sim 85 mas .
At this resolution , the images reveal a single continuum feature in the northern component of BRI 1202–0725 , and two continuum features in the southern component , separated by 320 mas .
This is similar to the structures seen in the high resolution images of the CO emission .

The extent of the observed continuum sources at 1.4 GHz and the derived brightness temperatures are consistent with nuclear starbursts .
Moreover , the absence of any compact high-brightness temperature source suggests that there is no radio-loud AGN in BRI 1202–0725 .