Oral Presentation

Unveiling heavily obscured SMBH growth in the early universe

Author(s): Naoki Matsumoto (Tohoku univ.)

Presenter: Naoki Matsumoto (Tohoku University)

Heavily obscured AGN in the early universe is an important population that represents an early violent growth phase of the SMBHs and host spheroidal components. Recent deep/wide surveys show the possibility that many luminous AGN are so obscured that they could be undetectable even in the hard X-ray band (i.e., heavily obscured AGN) at z>3 and they have large contribution to overall SMBHs growth rate. We performed a search for z>3 heavily obscured AGN in the XMM-LSS and COSMOS field focusing on their strong rest-frame NIR emission originated from AGN hot dust. As a result of the selection, ~70% of selected sources are not detected by the deep X-ray survey in these fields. SED fitting analysis on all selected candidates revealed that the AGN bolometric luminosities reach log(Lbol)~46-48, indicating that they can be heavily obscured and host a SMBH under vigorous growth phase. In order to evaluate their contribution to the cosmic SMBH growth rate, we estimated the black hole accretion rate density (BHAD) utilizing the estimated Lbol. The estimated BHAD of including heavily obscured AGN significantly exceeds the previous X-ray studies and reaches the theoretical simulations that reproduce the observed massive SMBHs in the present day.