Study on the Characterization of Intra-Day Variability in the Mid-infrared of Blazars

The variability is one of the most fundamental observational features of Blazars, the generation of Intra-Day Variability (IDV) is still a controversial issue. In this paper, we combine the 4LAC-DR2 catalog with the fifth Roma-BZCAT catalog to study the characteristics of mid-infrared IDV of different classes of Blazars using data from the ALLWISE project. The results show that: (1) The IDV of Low Synchrotron Peaked Blazars (LSPs) exhibit larger variability amplitudes compared to Intermediate Synchrotron Peaked Blazars (ISPs) and High Synchrotron Peaked Blazars (HSPs); (2) The IDV of Flat Spectrum Radio Quasars (FSRQs) also exhibit larger variability amplitudes compared to BL Lacertae objects (BL Lacs), and the color changes of both tend to become bluer when brighter; (3) The IDV of Fermi-detected Blazars exhibits a smaller variability amplitude compared to Non-Fermi-detected Blazars. Based on the study of the above results, we suggest that Blazars' observed emission in the mid-infrared band may come from a spatial scale range of ~10^-4 pc, that its IDV production may be related to physical processes intrinsic the jet, and that the amplitudes of the IDV may be closely related to the synchrotron peak of the Spectral Energy Distribution (SED).