Luca Ighina
INAF, Osservatorio Astronomico di Brera, Italy

Abstract
In recent years, the discovery of hundreds of  QSOs at z>5 has allowed the community to characterise the properties of the most extreme SMBHs in the early Universe.
Indeed, these objects are extremely useful tools to study the formation and the early evolution of seed BHs. In particular,  the radio-loud (RL) population, characterised by the presence of two relativistic jets, can potentially provide the strongest constraints on the growth of SMBHs in the early Universe. However, the properties of this class are still poorly constrained, due to low statistics. In this talk I will describe our efforts in constraining the evolution of the high-z RL QSO population. In particular, I will present the selection of new high-z RL QSO candidates from wide area radio (RACS) and optical/NIR (DES and PanSTARRS) surveys and their identification as z>5 systems through spectroscopic observations. Together with other RL QSOs at similar redshifts from the literature, they constitute currently the largest well-defined sample of RL QSOs at z>5 currently available, which can be used in order to constrain the redshift evolution of this population (in terms of emission and obscuration) and of their space density. At the same time, I will also describe how dedicated multi-wavelength (radio, NIR and X-ray) observations of these sources are essential in order to help constrain the properties of the SMBHs and jets hosted in these extreme systems. Finally, I will show how future surveys (EMU, LSST, EUCLID) will allow us to push these studies to unprecedented redshifts.

2024 June 07, 13:30

IA/U.Lisboa
Observatório Astronómico de Lisboa (Seminar room)
Tapada da Ajuda, 1349-018 Lisboa