We have observed the composite active galactic nucleus ( AGN ) -starburst galaxy NGC 6764 with the Very Long Baseline Array at 1.6 and 4.9 GHz .
These observations have detected a “ core-jet ” structure and a possible weak counterjet component at 1.6 GHz .
The upper limits to the core and jet ( 1.6 - 4.9 GHz ) spectral index are 0.6 and 0.3 , respectively .
Taken together with the high brightness temperature of \sim 10 ^ { 7 } K for the core region , the radio emission appears to be coming from a synchrotron jet .
At a position angle of \sim 25 \arcdeg , the parsec-scale jet seems to be pointing closely toward the western edge of the southern kpc-scale bubble in NGC 6764 .
A real connection between the parsec- and sub-kpc-scale emission would not only suggest the presence of a curved jet , but also a close link between the AGN jet and the radio bubbles in NGC 6764 .
We demonstrate that a precessing jet model can explain the radio morphology from parsec- to sub-kpc scales , and the model best-fit parameters of jet speed and orientation are fully consistent with the observed jet-to-counterjet surface brightness ratio .
The jet however appears to be disrupted on scales of hundreds of parsecs , possibly due to interaction with , and entrainment of the interstellar medium gas , which subsequently leads to the formation of bubbles .
The jet energetics in NGC 6764 suggest that it would take 12 - 21 Myr to inflate the ( southern ) bubble .
This timescale corresponds roughly to the starburst episode that took place in NGC 6764 about 15 - 50 Myr ago , and could be indicative of a close connection between jet formation and the starburst activity in this galaxy .