[2603.18109] Discovery of Bimodal Drift Rate Structure in FRB 20240114A: Evidence for Dual Emission Regions

Astrophysics > High Energy Astrophysical Phenomena arXiv:2603.18109 (astro-ph) This paper has been withdrawn by arXiv Admin [Submitted on 18 Mar 2026 (v1), last revised 3 Apr 2026 (this version, v2)] Title:Discovery of Bimodal Drift Rate Structure in FRB 20240114A: Evidence for Dual Emission Regions Authors:Santosh Arron View a PDF of the paper titled Discovery of Bimodal Drift Rate Structure in FRB 20240114A: Evidence for Dual Emission Regions, by Santosh Arron No PDF available, click to view other formats Abstract:We report the discovery of bimodal structure in the drift rate distribution of upward-drifting burst clusters from the hyperactive repeating fast radio burst FRB 20240114A. Using unsupervised machine learning (UMAP dimensionality reduction combined with HDBSCAN density-based clustering) applied to 233 upward-drifting burst clusters from the FAST telescope dataset, we identify a distinct subpopulation of 45 burst clusters (Cluster C1) with mean drift rates 2.5x higher than typical upward-drifting burst clusters (245.6 vs 98.1 MHz/ms). Gaussian mixture modeling reveals strong evidence for bimodality (delta-BIC = 296.6), with clearly separated modes (Ashman's D = 2.70 > 2) and a statistically significant gap in the distribution (11.3 sigma). Crucially, we demonstrate that this bimodality persists when restricting the analysis to single-component (U1) burst clusters only (delta-BIC = 19.9, Ashman's D = 2.71), confirming that the result is not an artifact of combini...