Speaker
Description
Obscured Active Galactic Nuclei (AGN) are the largest population of
accreting supermassive black holes. The demographics of the most
heavily obscured nuclei, however, is still largely uncertain,
especially at early cosmic times, where they may dominate the whole
AGN statistics.
A promising way to select heavily obscured AGN is through their radio
emission, which is largely unaffected by obscuration and, for
sufficiently powerful nuclei, can be revealed in excess of that
produced by star formation.
In this talk, I will present a detailed investigation of the
effectiveness of radio selection to discover heavily obscured AGN.
We first extend AGN population synthesis models of the cosmic X-ray
background to the radio band. Then, we make predictions for the major
extragalactic fields covered by both deep X-ray and radio data. Our
results show that, while X-ray selection is generally more effective
in detecting unobscured AGN, radio selection is significantly more
effective in detecting the most heavily obscured, Compton-thick
AGN. Thousands of Compton-thick nuclei are indeed expected to hide
among the sources of popular radio catalogs.
I will finally present expectations for the number of AGN to be
detected by the continuum surveys of the Square Kilometer Array
Observatory (SKAO). The SKAO is expected to detect more than 2000 AGN at
z>6, and even some tens at z>10: half of them are expected to be
Compton-thick.
| Reasearch area | Extragalactic Continuum (galaxies/AGN, galaxy clusters) |
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