Mid-infrared Variability in Nearby Galaxies from the MaNGA Sample

Abstract We use mid-infrared variability in galaxies to search for active galactic nuclei (AGN) in the local universe. We use a sample of 10,220 galaxies from the Mapping Nearby Galaxies at Apache Point Observatory survey, part of the Sloan Digital Sky Survey. For each galaxy, we examine its mid-infrared variability in the W2 [4.6 μ m] band over 13 years using data from the Wide Infrared Survey Explorer (WISE) All-Sky and Near Earth Objects WISE missions. We demonstrate that we can detect variability signatures as small as about 7% in the rms variation of W2 flux for the majority of cases. Using other AGN signatures of the variable galaxies, such as optical narrow lines, optical broad lines, and WISE W1 − W2 colors, we show that ∼75% of the variables show these additional AGN signatures, indicating that the bulk of these cases are likely to be AGN. We also identify seven galaxies that have light curves characteristic of tidal disruption events. We present here a publicly available catalog of the light-curve variability in W2 of these galaxies.