Statistical Substructure of ISP Blazar Variability: Evidence for a Distinct High-Variability Population in 4LAC-DR3 (v4: 3C 66A Confirmation)

Key Points

• This research aims to identify distinct variability patterns within a specific subgroup of ISP blazars from the 4LAC-DR3 catalog.
• Analyzed 515 ISP blazar sources using Gaussian Mixture Model (GMM) to distinguish high-variability subpopulation (C3) with N=129.
• Conducted individual Swift X-ray Telescope (XRT) analysis of 3C 66A, including 27,059 photons over 69.7 hours.
• Performed cross-source spectral analysis to compare variability characters and signatures among C3 members.
• Identified the C3 high-variability subpopulation showing 2-4x excess fractional variability, independent of observational biases.
• Confirmed X-ray spectral softening in 3C 66A with a KS test p-value of 1.15e-13, supporting previous findings.
• Cross-source comparisons reveal consistent spectral signatures among C3 members despite differing variability characteristics.