research

radio-loud quasars are essential to understand the accretion and growth of black holes, especially in the early universe. there are over 300 quasars at z>5, but black hole masses are only attained for 2 of them. the great void lies before us limits our understanding to the effect of radio jets in the early universe.

the main problem we are coping with: quasars at the early universe are surprisingly heavy. if we trace back their evolutionary track, they might undergo a long period of supper-eddington accretion. at the same time, there is theoretical and observational evidence that jet can help the black holes to accrete faster. if gathering enough info on radio-loud population, the knowledge to their accretion history might help us to crack the myth of the earliest black holes in the universe.

to achieve this, we carried out optical/nir spectroscopy with mods/luci slit spectroscopy at lbt. our current sample of ~20 quasars will triple the size of existing sample on black hole properties measurements to z>5 radio-loud quasars. also more interesting infos on the blueshifts from CIV and MgII will be accessible in our samples. stay tuned!

blazars are a sub-class of agns that appear to be extremely variable and bright. this is due to their superluminal radio jets are pointing at us at a very small angle. based on this scenario, blazars are expected to show compact radio morphology.

vlass is a radio sky survey with high angular resolution. the before not resolved features are now clear identified in its images. to put it in another way, the compact radio morphology in previous surveys might look different in vlass. taking advantage of the unprecedented radio survey images and a novel automatic algorithm on morphology, we are resolving structures for blazar candidates, and rule out those that show clear non-blazar morphology – symmetrical face-on jets.

check out the manuscript of the work here.