Abstract

Deep X-ray surveys have shown that the space density of high-luminosity AGNs peaked at higher redshifts than lower luminosity AGNs, suggesting that the most massive SMB Hs (M_BH approx 10⁸ – 10⁹ M_sun) grew first. The implication of these results is that the most rapidly growing SMB Hs in the local Universe should be of comparatively low mass (M_BH < 10⁷ M_sun). We will show that this is indeed the case by providing X-ray and mid-IR spectral constraints of the most complete census of AGN activity to D 6 M_sun). Arguably, the most direct method for measuring the true intrinsic luminosity of the central source is through sensitive hard X-ray analyses. By combining X-ray data from Chandra, XMM-Newton, Suzaku, Swift and Beppo-SAX with mid-IR spectroscopy from Spitzer-IRS we will show that these AGNs appear to be intrinsically luminous objects, many of which are heavily obscured at X-ray energies (< 10 keV). Furthermore, we constrain the relative mass accretion rates, and hence present-day growth rates of these AGNs and conclude that AGNs hosting SMBHs with M_BH approx 10⁶ M_sun are amongst the most rapidly growing in the local Universe.