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Session: Extragalactic Astronomy and Astrophysics

Name: Dr. Ioannis Georgantopoulos (National Observatory of Athens)
Coauthors: No coauthors were included.
Type: Oral
Title: X-ray Active Galactic Nuclei at high redshift
Abstract:

X-ray observations provide the most efficient means to detect Active Galactic Nuclei that is accretion into supermassive black holes. This is because X-rays unlike the optical wavelengths are hardly affected by intrinsic obscuration. It appears that Active Galactic Nuclei evolve in parallel with the star-formation density in galaxies up to redshifts of z=2-3 (the cosmic noon epoch). Here, we provide the most accurate yet estimate of the X-ray luminosity function at even higher redshifts in the Early Universe (3>z>6) using the largest sample so far (>600) of high-redshift AGNs selected in the Chandra deep fields, Legacy-COSMOS and XMM-XXL northern fields. One third of the X-ray sources have available spectroscopic information, while we derived the X-ray spectral parameters for all the sources in our sample in order to determine the intrinsic obscuration. Our estimated luminosity function is in agreement with an exponential decline model similar to what is witnessed at optical wavelengths, while the derived BHAD lies well below the star-formation density. Comparison with a number of cosmological galaxy simulations is presented.