EM149
Resolving the faintest radio quasars detected by LOFAR
Evolutionary models for galaxy formation predict the host galaxies of unobscured quasars to exhibit sharply decreasing levels of star-formation due to radiative feedback. However, the extremely weak emission associated with low-level star-formation and the relatively short time-scales over which quenching occurs makes identifying quasar host galaxies during this late evolutionary stage challenging. We recently identified extremely faint radio emission from two highly magnified quasars at redshifts of 1.7 and 2.8 with LOFAR-LoTSS DR2. After correcting for the lensing magnifications, the two radio sources have intrinsic flux-densities at 144 MHz of 13 and 58 uJy, respectively, corresponding to radio-derived star-formation rates of just 5.5 and 73 M/yr. Here we request e-MERLIN+EVN multi-scale imaging to determine if any of the detected radio emission is due to weak jets associated with the quasars. These data will either confirm the extremely low radio-derived star-formation rates, which would be in agreement with galaxy formation models, or will find evidence for significant AGN activity, in conflict with models for radio source populations at uJy flux densities.
Observation pages at the EVN archive:
Context for this dataThis data is part of the archive of VLBI data maintained by JIVE on behalf of the EVN, a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa. The EVN archive itself has the DOI https://doi.org/10.17616/R3Z197