Selection of AGN candidates in the GOODS-South Field through
  SPITZER/MIPS 24 microns variability
  We present a study of galaxies showing mid-infrared variability in the
deepest Spitzer/MIPS 24 $\mu$m surveys in the GOODS-South field. We divide the
dataset in epochs and subepochs to study the long-term (months-years) and the
short-term (days) variability. We use a $\chi^2$-statistics method to select
AGN candidates with a probability $\leq$ 1% that the observed variability is
due to statistical errors alone. We find 39 (1.7% of the parent sample) sources
that show long-term variability and 55 (2.2% of the parent sample) showing
short-term variability. We compare our candidates with AGN selected in the
X-ray and radio bands, and AGN candidates selected by their IR emission.
Approximately, 50% of the MIPS 24 $\mu$m variable sources would be identified
as AGN with these other methods. Therefore, MIPS 24 $\mu$m variability is a new
method to identify AGN candidates, possibly dust obscured and low luminosity
AGN that might be missed by other methods. However, the contribution of the
MIPS 24 $\mu$m variable identified AGN to the general AGN population is small
($\leq$ 13%) in GOODS-South.
