Characterization and Radio SED fitting of radio-loud high-redshift quasars

As part of my previous project on searching for high-redshift quasars with SED fitting for 4MOST/ChANGES, we identified a significant number of candidates with radio detections. To confirm their nature and characterize their properties, we carried out spectroscopic follow-up observations at the Palomar Observatory and the Gemini North Observatory, which led to the confirmation of 3 radio-loud quasars at z > 5.

How can we combine the radio, infrared, and optical information of these sources to build a more complete picture of radio-loud AGN at high redshift — and use that to prioritize the most promising candidates for future follow-up?

I am currently co-supervising Edgar Harutyunyan, a senior-year bachelor student from Leipzig University, who is studying the radio properties of these sources and building a radio SED fitting framework. Combined with the existing optical and infrared photometry, this will enable a multiwavelength SED fitting across the radio–IR–optical bands, providing a physically motivated way to rank candidates by the probability of being genuine radio-loud high-redshift quasars.

The higher-probability sources selected from this multiwavelength approach will be prioritized for upcoming spectroscopic follow-up campaigns. Stay tuned for updates!