Affiliation: Instituto de Astrofísica e Ciências do Espaço – U. de Lisboa

Contribution: Oral

Title: Do radio-powerful AGN exist in the EoR?

Abstract: The existence of powerful AGN has been established well within the first Gyr of the Universe, through observations of tens of optically or near-infrared selected QSOs up to the currently highest redshift of z~8. Theoretical work has been developed showing how super-massive (M ∼ 10⁹ M_⊙) black holes can exist at even earlier epochs, depending on the fast assembly and growth of a suitable seed. Some of these sources should be bright at radio wavelengths, and detectable even within the Epoch of Reionisation. Such sources will be paramount to the understanding of the earliest stages of galaxy evolution but even more, as they should allow for the direct study of neutral hydrogen in the Epoch of Reionization, through SKA observations of the HI 21cm forest. In spite of these high expectations, it has been essentially impossible for radio surveys to reveal such “rosetta stone” systems, allowing for an important “detectability” (do such sources even exist at such early times, or are they just later manifestations of the EoR little red dots revealed by JWST?) vs “identification” (inadequate multiwavelength coverage) discussion. With the recent generation of SKA-percursor wide-deep radio surveys, however, by focusing on regions of the sky already hosting a comprehensive range of multiwavelength data, one may shed light on how the identification of EoR radio AGN can finally be achieved. Here, we will discuss recent strategies for the identification of the earliest radio-powerful AGN, highlighting recent work on the MIGHTEE MeerKAT and EMU ASKAP radio surveys. We will also discuss how massive whole-sky radio surveys and coordination with powerful NIR-to-mm facilities, like MOONS, JWST and ALMA, will be essential in the leading-up to an even more ambitious SKA-ELT era.

This contribution can be found here (pdf).