Discovery of a radio jet in the cloverleaf quasar at z = 2.56

The fast growth of supermassive black holes and their feedback to the host galaxies play an important role in regulating evolution galaxies, especially early Universe. However, due cosmological dimming limited angular resolution most observations, it is difficult resolve from active galactic nuclei (AGN) galaxies. Gravitational lensing, for its magnification, provides a powerful tool spatially differentiate emission originated AGN galaxy at high redshifts. Here we report discovery radio lobe strongly lensed starburst quasar, H1413+117 or Cloverleaf redshift $z= 2.56$, based on observational data optical, sub-millimetre, wavelengths. With both parametric non-parametric lens models with reconstructed images source plane, find differentially lensed, kpc scaled, single-sided lobe, located ${\sim}1.2\,\mathrm{kpc}$ north west plane. From spectral energy distribution bands, that has turning point residing between 1.5 GHz 8 GHz, indicating age 20--50 Myr. This could indicate switching quasar jet mode mode.