2008AJ....136..344M

We present 8.4 GHz Very Large Array (VLA) A configuration and 1.4 GHz Very Long Baseline Array (VLBA) results on the radio continuum emission from the highest redshift radio-loud quasar known to date, the z = 6.12 QSO J1427+3312. The VLA observations show an unresolved steep spectrum source with a flux density of 250±20 µJy at 8.4 GHz and a spectral index value of α^8.4 _1.4= -1.1. The 1.4 GHz VLBA images reveal several continuum components with a total flux density of 1.778±0.109 mJy, which is consistent with the flux density measured with the VLA at 1.4 GHz. Each of these components is resolved with sizes of a few milliarcseconds, and intrinsic brightness temperatures on the order of 10⁷ to 10⁸ K. The physical characteristics as revealed in these observations suggest that this quasi-stellar object may be a Compact Symmetric Object (CSO), with the two dominant components seen with the VLBA, which are separated by 31 mas (174 pc) and have intrinsic sizes of ∼22-34 pc, being the two radio lobes that are confined by the dense interstellar medium. If indeed a CSO, then the estimated kinematic age of this radio source is only 10³ yr.