Talk abstract details
Exploring extremely obscured accretion
Abstract
A high X-ray-to-optical flux ratio (high FX /
FOpt) is believed to be a good indication of
obscured accreting sources (QSO2) at $zgeq1$.
The study of these sources is currently one of
the hottest topics in extragalactic astronomy,
given the now clear strong connection between
AGN and galaxy evolution. We present a
programme on-going at the GTC to identify
sources with FX/FOpt$>$20 at high X-ray flux. At the moment we have 19 identifications (15 with GTC) in $z=0.5-2.9$ including one BL Lac, one "normal" galaxy, and both Narrow and (surprisingly) Broad Emission Line AGNs. Preliminary analyses show that all but one of them would be "X-ray QSO2s" (high X-ray luminosity and indications of substantial X-ray absorption). We will discuss the good quality X-ray spectra and optical spectra obtained so far, and what they teach us about obscured accretion at high redshift.
FOpt) is believed to be a good indication of
obscured accreting sources (QSO2) at $zgeq1$.
The study of these sources is currently one of
the hottest topics in extragalactic astronomy,
given the now clear strong connection between
AGN and galaxy evolution. We present a
programme on-going at the GTC to identify
sources with FX/FOpt$>$20 at high X-ray flux. At the moment we have 19 identifications (15 with GTC) in $z=0.5-2.9$ including one BL Lac, one "normal" galaxy, and both Narrow and (surprisingly) Broad Emission Line AGNs. Preliminary analyses show that all but one of them would be "X-ray QSO2s" (high X-ray luminosity and indications of substantial X-ray absorption). We will discuss the good quality X-ray spectra and optical spectra obtained so far, and what they teach us about obscured accretion at high redshift.