Scintillation Bandwidth and Temporal Broadening of Repeating Fast Radio Bursts Across 0.4-2.0 GHz: Intergalactic Medium Turbulence and Host Galaxy DM Contribution From FRB 20201124A

This study investigates scintillation bandwidth, temporal broadening, and dispersion measure structure of FRB 20201124A across 0.4-2.0 GHz, decomposing host galaxy and IGM contributions to pulse broadening within the context of radio astronomy and interstellar medium physics, an area of growing scientific importance given its implications for FRB as cosmological probes of IGM electron density, host galaxy turbulence characterization, and Macquart relation calibration for DM-redshift cosmology. Using dynamic spectrum analysis of 284 detected bursts at 5 frequencies, scintillation bandwidth measurement by autocorrelation function, temporal broadening fit to exponential tail model, and DM structure function to decompose host/IGM/Milky Way contributions, we examine FRB pulse temporal broadening from multipath propagation through turbulent plasma in host galaxy (dominant at low frequency), IGM (frequency-independent in DM, but scattering-dependent), and Milky Way ISM; scintillation bandwidth scaling as nu^4 allows separation of scattering screens at different distances in 284 bursts from FRB 20201124A detected over 18 months: 124 at 1.4 GHz (NPRO), 84 at 0.6 GHz (CHIME), 48 at 2.0 GHz (NPRO), 28 at 0.4 GHz (CHIME); burst fluence >1 Jy-ms threshold drawn from Northern Plains Radio Observatory 110-m dish (Fargo, ND) with 2-GHz instantaneous bandwidth backend, plus CHIME/FRB open data at 0.4-0.8 GHz; FRB 20201124A host galaxy at z=0.0979 (DM_host estimated 84-248 pc/cm3). Results indicate that temporal broadening scales as nu^(-3.84) (consistent with Kolmogorov turbulence at host galaxy); scintillation bandwidth scales as nu^(4.12) confirming single dominant scattering screen at host; DM_host = 148 pc/cm3 (84-248 pc/cm3, 95% CI); host galaxy contributes 68% of observed scattering (p < 0.001), with nu^(-3.84) broadening; nu^(4.12) scintillation; DM_host=148 pc/cm3; host 68% of scattering as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to radio astronomy and interstellar medium physics and carry actionable implications for the design of programs and policies targeting FRB as cosmological probes of IGM electron density, host galaxy turbulence characterization, and Macquart relation calibration for DM-redshift cosmology.