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We present a study of galaxies showing mid-infrared variability in data takenin the deepest Spitzer/MIPS 24 $\mu$m surveys in the GOODS-South field. Wedivide 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. That is, 0.03sources $\times$ arcmin$^{-2}$ for both, long-term and short-term variablesources. After removing the expected number of false positives inherent to themethod, the estimated percentages are 1.0% and 1.4% of the parent sample forthe long-term and short-term respectively. We compare our candidates with AGNselected in the X-ray and radio bands, and AGN candidates selected by their IRemission. Approximately, 50% of the MIPS 24 $\mu$m variable sources would beidentified as AGN with these other methods. Therefore, MIPS 24 $\mu$mvariability is a new method to identify AGN candidates, possibly dust obscuredand low luminosity AGN, that might be missed by other methods. However, thecontribution of the MIPS 24 $\mu$m variable identified AGN to the general AGNpopulation is small ($\leq$ 13%) in GOODS-South.

Selection of AGN candidates in the GOODS-South Field through SPITZER/MIPS 24 $\mu$m variability