2025/06/10 by A. Annuar, D. M. Alexander, Annuar, A. +45
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · pdf · doi:10.48550/arxiv.2506.08527
openalex publication_date 2025/06/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a census of the Compton-thick (CT) active galactic nucleus (AGN) population and the column density (N_\rmH) distribution of AGN in our cosmic backyard using a mid-infrared selected AGN sample within 15 Mpc. The column densities are measured from broadband X-ray spectral analysis, mainly using data from Chandra and NuSTAR. Our sample probes AGN with intrinsic 2-10 keV luminosities of L\rm 2-10, int = 1037-1043 erg s-1, reaching a parameter space inaccessible to more distant samples. We directly measure a 32+30-18% CT AGN fraction and obtain an N_\rmH distribution that agrees with that inferred by the Swift-BAT survey. Restricting the sample to the largely unexplored domain of low-luminosity AGN with L\rm 2-10, int ≤ 1042 erg s-1, we found a CT fraction of 19+30-14%, consistent with those observed at higher luminosities. Comparing the host-galaxy properties between the two samples, we find consistent star formation rates, though the majority of our galaxy have lower stellar masses (by ≈ 0.3 dex). In contrast, the two samples have very different black hole mass (M\rm BH) distributions, with our sample having ≈1.5 dex lower mean mass (M\rm BH ∼ 106 M_\odot). Additionally, our sample contains a significantly higher number of LINERs and H_\rmII-type nuclei. The Eddington ratio range probed by our sample, however, is the same as Swift-BAT, although the latter dominates at higher accretion rates, and our sample is more evenly distributed. The majority of our sample with λ\rm Edd ≥ 10-3 tend to be CT, while those with λ\rm Edd < 10-3 are mostly unobscured or mildly obscured.