The goal of this proposal is to establish a method for the quantification of fundamental active galactic nucleus (AGN) properties, i.e., black hole (BH) masses and accretion rates, in high-redshift and obscured AGN. We aim to use infrared spectra from the Spitzer and Herschel space telescopes to study the kinematics and fluxes of gas emission lines originating from the AGN narrow-line region (NLR). Our first results indicate that the mid-infrared (MIR) NLR line widths follow the relation between the BH mass and the velocity dispersion of the stars in the bulge. This result indicates that the NLR kinematics can be used as a surrogate of the stellar kinematics in the computation of BH masses because they are influenced by the bulge gravitational potential. The MIR NLR luminosities correlate with the AGN bolometric luminosity, allowing us to measure its accretion rate. Still, two tests need to be performed prior to the use of NLR kinematics for the computation of BH properties. We need to i) examine how susceptible they are on outflows by studying their line profiles in wavelengths with little obscuration and in radio-loud and highly-accreting AGN, and ii) test that our technique can be applied in bright local AGN, which are the analogues of many high-z AGN. To populate the relation between the BH mass and the stellar velocity dispersion at high luminosities, we will use near-infrared data obtained with adaptive-optics assisted spectographs, to measure the stellar kinematics in local quasars. Once our tool is calibrated, we will use Spitzer and Herschel datasets to derive the first BH mass estimates of obscured type-2 AGN and to investigate for evolution in the masses of BHs from z~0 to z~3. Our tool will enable studies of the growth of (obscured) BHs and their host galaxies since the Universe was young and it can be largely used for the interpretation of future space missions datasets, such as James Webb Space Telescope spectra.
Call for proposal
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