The Highest Redshift Quasar at $z=7.085$: A Radio Quiet Source

We present 1-2 GHz Very Large Array A-configuration continuum observations on the highest redshift quasar known to date, the $z=7.085$ quasar ULAS J112001.48+064124.3. The results show no radio continuum emission at the optical position of the quasar or its vicinity at a level of $geq 3sigma$ or $23.1 mu$Jy beam$^{-1}$. This $3sigma$ limit corresponds to a rest frame 1.4 GHz luminosity density limit of $L_{ u,1.4,GHz} < 1.76 times 10^{24}$ W Hz$^{-1}$ for a spectral index of $alpha=0$, and $L_{ u,1.4,GHz} < 1.42 times 10^{25}$ W Hz$^{-1}$ for a spectral index of $alpha=-1$. The rest-frame 1.4 GHz luminosity limits are $L_{rad} < 6.43 times 10^6 L_{odot}$ and $L_{rm rad} < 5.20 times 10^7 L_{odot}$ for $alpha=0$ and $alpha=-1$, respectively. The derived limits for the ratio of the rest frame 1.4 GHz luminosity density to the $B$-band optical luminosity density are $Rrlap{}_{1.4}^{*} < 0.53$ and $< 4.30$ for the above noted spectral indices, respectively. Given our upper limits on the radio continuum emission and the radio-to-optical luminosity ratio, we conclude that this quasar is radio-quiet and located at the low end of the radio quiet distribution of high redshift ($z gtrsim 6$) quasars.