Quasi-Periodic Oscillations in Gamma-Ray Bursts' Prompt Light Curves
Mariusz Tarnopolski
TL;DR
This study addresses quasi-periodic oscillations in the prompt emission of long gamma-ray bursts by applying wavelet-based analysis to a large Swift/BAT GRB sample, identifying 34 new QPOs. The method uses 64 ms binned light curves and wavelet scalograms with significance testing against a CARMA model, requiring QPOs to last at least three cycles and exceed $3\sigma$. The results reveal multiple QPOs per burst, including constant-leading periods and chirping signals, with notable examples such as GRB 090709A; harmonics and resonance patterns (e.g., $2:3$, $4:5$, $2:3:4$) are reported. The authors interpret the findings in the context of accretion-disk physics around black holes, favoring mechanisms like nonplanar relativistic orbits, Lense-Thirring precession, and shock oscillations, and discuss the implications for GRB central engine dynamics and jet formation.
Abstract
I report on the discovery of 34 new quasi-periodic oscillations (QPOs) in the prompt light curves of long gamma-ray bursts (GRBs) from the Swift/BAT catalog: with one or more constant leading periods, as well as several chirping signals. This is the largest homogenously identified sample or GRB QPOs to date. The presence of QPOs suggests the existence of characteristic time scales that at least in some GRBs might be related to the dynamical properties of plasma trajectories in the accretion disks powering the relativistic jets. Several scenarios for their origin were examined. We identify non-planar orbits around Kerr black holes, the Lense-Thirring effect, and shock oscillations as plausible mechanisms for the QPO generation.