GRB minimum variability timescale with Insight-HXMT and <i>Swift</i>

The dissipation process of GRB prompt emission is still unknown. Study temporal variability may provide a unique way to discriminate the imprint inner engine activity from geometry and propagation related effects. We define minimum timescale (MVT) as shortest duration individual pulses that shape light curve for sample GRBs test correlations with peak luminosity, Lorentz factor, jet opening angle. compare these predictions recent numerical simulations relativistic structured -- possibly wobbling assess value MTV probe prompt-emission physics. used detection algorithm mepsa identify pulse within time history estimate its full width half maximum (FWHM). applied this framework two sets GRBs: Swift (from 2005 July 2022) Insight-HXMT June 2017 2021, including 221009A). then selected 401 measured z correlations. On average short have significantly shorter MVT than long GRBs. distribution extended such 060614 211211A compatible only This provides new clue on progenitor's nature. anticorrelates luminosity. confirm anticorrelation factor find correlation angle estimated afterglow, along an inverse number pulses. can emerging putative class are suggested be produced by compact binary mergers. For otherwise typical GRBs, different between angle, explained context structured, wobbling, weakly magnetised jets. (summarised)