An unbiased view of X-ray obscuration amongst active galactic nuclei with NuLANDS

Nearly all active galactic nuclei (AGN) are obscured in X-rays behind column densities of N_H ≥ 10²² cm^-2. Hard X-ray studies have proven very effective to quanitfy the levels of obscuration amongst AGN, up to and just above the Compton-thick limit (N_H ∼ 1.5 × 10²⁴ cm^-2). However, Compton-thick sources with N_H values beyond this limit are typically missed in hard X-ray all-sky surveys such as Swift/BAT, requiring many studies to apply considerable bias corrections to account for the loss. Incorrectly quanitfying the heavily obscured AGN population can have a dramatic effect on synthesis models designed to fit the Cosmic X-ray Background spectrum, due to their significant contribution to the peak flux of the background at ~30 keV. This is what motivated the NuSTAR Local AGN N_H Distribution Survey (NuLANDS) - a NuSTAR 1 Ms legacy survey of an obscuration-independent, infrared selected sample of AGN, undetected by BAT and unobserved by NuSTAR before - a considerable number of which are predicted to be heavily obscured. NuSTAR is the first true X-ray focusing instrument capable of spectral analysis > 10 keV, and as such can and will place robust constraints on the N_H values of these elusive AGN. In this poster, I will present the first results from NuLANDS, including multiple newly identified Compton-thick AGN, previously undetected in the Swift/BAT 70-month catalog. I will further highlight the exciting prospects for the complete NuLANDS sample, with the ultimate goal of constructing a representative N_H distribution of AGN in the local Universe, requiring minimal bias corrections.