New radio-loud QSOs at the end of the Re-ionization epoch

We present the selection of high-redshift ($z\gtrsim5.7$) radio-loud (RL) quasi-stellar object (QSO) candidates from combination radio Rapid ASKAP Continuum Survey (RACS; at 888 MHz) and optical/near-infrared Dark Energy (DES). In particular, we selected six brighter than $S_{\rm 888MHz}>1$ mJy beam$^{-1}$ ${\rm mag}(z_\mathrm{{DES}})<21.3$ using dropout technique (in $i$-band). From this sample, were able to confirm high-$z$ nature ($z\sim6.1$) two sources, which are now among highest-redshift RL QSOs currently known. Based on our Gemini-South/GMOS observations, neither shows a prominent Ly$\alpha$ emission line. This suggests that both sources likely be weak emission-line hosting jets would therefore further strengthen potential increase fraction recently found in literature. However, multiwavelength observations needed constrain properties these their relativistic jets. discovery estimated space density redshift range $5.9<z<6.4$ 0.13$^{+0.18}_{-0.09}$ it consistent with expectations based current knowledge blazar population up $z\sim5$.