Title: A New Compton-thick AGN in our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR,
Abstract: NGC 1448 is one of the nearest luminous galaxies ($L_{8-1000\mu m} >$ 10$^{9}
L_{\odot}$) to ours ($z$ $=$ 0.00390), and yet the active galactic nucleus
(AGN) it hosts was only recently discovered, in 2009. In this paper, we present
an analysis of the nuclear source across three wavebands: mid-infrared (MIR)
continuum, optical, and X-rays. We observed the source with the Nuclear
Spectroscopic Telescope Array (NuSTAR), and combined this data with archival
Chandra data to perform broadband X-ray spectral fitting ($\approx$0.5-40 keV)
of the AGN for the first time. Our X-ray spectral analysis reveals that the AGN
is buried under a Compton-thick (CT) column of obscuring gas along our
line-of-sight, with a column density of $N_{\rm H}$(los) $\gtrsim$ 2.5 $\times$
10$^{24}$ cm$^{-2}$. The best-fitting torus models measured an intrinsic 2-10
keV luminosity of $L_{2-10\rm{,int}}$ $=$ (3.5-7.6) $\times$ 10$^{40}$ erg
s$^{-1}$, making NGC 1448 one of the lowest luminosity CTAGNs known. In
addition to the NuSTAR observation, we also performed optical spectroscopy for
the nucleus in this edge-on galaxy using the European Southern Observatory New
Technology Telescope. We re-classify the optical nuclear spectrum as a Seyfert
on the basis of the Baldwin-Philips-Terlevich diagnostic diagrams, thus
identifying the AGN at optical wavelengths for the first time. We also present
high spatial resolution MIR observations of NGC 1448 with Gemini/T-ReCS, in
which a compact nucleus is clearly detected. The absorption-corrected 2-10 keV
luminosity measured from our X-ray spectral analysis agrees with that predicted
from the optical [OIII]$\lambda$5007\AA\ emission line and the MIR 12$\mu$m
continuum, further supporting the CT nature of the AGN.