Infrared-detected AGNs in the Local Universe
  Spitzer/IRAC color selection is a promising technique to identify hot
accreting nuclei, that is to say AGN, in galaxies. We demonstrate this using a
small sample of SAURON galaxies, and explore this further. The goal of this
study is to find a simple and efficient way to reveal optically obscured
nuclear accretion in (nearby) galaxies. We apply an infrared selection method
to the Spitzer Survey of Stellar Structures in Galaxies (S4G) sample of more
than 2500 galaxies, together with its extension sample of more than 400
galaxies. We use the Spitzer colors to find galaxies in the S$^{4}$G survey
containing a hot core, suggesting the presence of a strong AGN, and study the
detection fraction as a function of morphological type. We test this infrared
color selection method by examining the radio properties of the galaxies, using
the VLA NVSS and FIRST surveys. Using the radio data, we demonstrate that
galaxies displaying hot mid-infrared nuclei stand out as being (candidate)
active galaxies. When using, instead of Spitzer, colors from the lower spatial
resolution WISE mission, we reproduce these results. Hence multi-band infrared
imaging represents a useful tool to uncover optically obscured nuclear activity
in galaxies.
