Unsupervised Classification of Gamma-ray Bursts from Blazars (GRBBLs) with Machine Learning

Abstract

Blazars dominate the extragalactic ${\hat{I}}^3$-ray sky and show pronounced flares. Using public Fermi-LAT light curves for 732 blazars with secure redshifts, I implement an automated pipeline to identify and characterize ${\hat{I}}^3$-ray bursts from blazars (GRBBLs). Each event is modeled with an exponential rise/decay profile, and spectral variability is quantified via a constant fit. From 679 high-quality GRBBLs, I apply extreme deconvolution for unsupervised classification. The GRBBL population is remarkably homogeneous; the most robust split is in achromatic vs. chromatic events, with significant overlap. Removing spectral information yields a luminosity-driven classification in type-1 and type-2 GRBBLs, although this classification is not identified in all tests. This study establishes GRBBL population studies as a tool to study blazars. As a by-product of this project I identify a correlation between peak luminosity and timescales in GRBBLs.

To appear in the Proceedings of the IAU UniversAI conference, Athens, June 2025. This contribution is a summary of the work published in A&A, 698, 101 (arXiv:2410.21974)