January 1, 2010.
A large fraction of objects in the universe vary in brightness as a function of time. Whereas Kozlowski et al. (2010) investigated a large sample of variable AGN with the Spitzer Space Telescope in the mid-IR for the first time, the WISE telescope can probe AGN variability at much shorter time scales, ranging from hours to months. Also, WISE is an all-sky survey, and thereby provides a much larger catalogue of infrared sources to analyze. A comprehensive list of quasi-stellar objects (QSO) was generated using the NASA/IPAC Extragalactic Database (NED). The light curves of these 132,851 objects were obtained using WISE observations. The standard deviation and band-to-band correlation coefficients were calculated for each object. We consider sources in different variability levels where these variability levels correspond to the objects’ deviation from the median SD values of the light curve. In addition, we compute the variability of the objects over different time scales and compare the results to Kozlowski et al. (2010) to observe how variability of AGNs evolve over a period of hours to months. We present light curves of the most variable objects in our sample and characterize the variability of all the objects as a function of time.
NASA Jet Propulsion Laboratory (JPL)