We kindly invite you to the Tor Vergata Astrophysics Seminar on Wednesday November 22nd at 14:30 CET.


Join IN PERSON in Aula Paoluzi (Physics Department) or online on the MS Teams at: https://rebrand.ly/Seminar-Peca


To avoid issues with the connection, we encourage you to download and use the free MS Teams App.


TITLE: Unveiling the Dark Side of the Universe: Harnessing the Power of Big Data to Reveal a Hidden and Heavily Obscured AGN Population


SPEAKER: Dr. Alessandro Peca (University of Miami, USA)


ABSTRACT: We present a study of over 3000 X-ray AGN in the Stripe 82X field, analyzing their intrinsic properties and deriving model-independent obscured and unobscured AGN evolution up to redshift 4. Our findings reveal a discrepancy when tracing the black hole accretion density by comparing our results with current and up-to-date evolutionary models. Specifically, we find evidence for a heavily Compton-thick AGN population that remains undetected even when combining X-ray and infrared data at all redshifts. These results challenge our understanding of AGN evolution and suggest that Compton-thick sources play a larger role in the accretion history of AGN than previously thought. Building on these insights, we extend this work in two parallel endeavors: First, we introduce Stripe 82XL, an extension of the Stripe 82X survey. Leveraging data from both XMM and Chandra source catalogs, S82XL expands the survey area to a vast 55 square degrees, doubling the depth of its predecessor. Simultaneously, we are constructing the AGN-DataBase (AGN-DB), an archive for all the discovered AGN. AGN-DB offers a comprehensive catalog of AGN properties and classifications, leveraging the wealth of data from all the available archives and surveys.  With this double approach, we can capture fainter, more obscured, and higher redshift AGN, further improving our understanding of AGN evolution.