24–28 Mar 2025
Florence, Italy
Europe/Rome timezone

Investigating High-Energy Time Lags in Gamma-Ray Bursts with Fermi-LAT and GBM

25 Mar 2025, 14:00
30m
Florence, Italy

Florence, Italy

Piazza Adua, 1, 50123 Firenze, Italia

Speaker

Ms Claudia Maraventano (Università di Palermo)

Description

Time lags between the arrival time of different photon energies provide valuable insight into the emission mechanisms of Gamma-Ray Bursts (GRBs). Using data from the Fermi Gamma-ray Burst Monitor (GBM, between 10 - 500 keV) and the Large Area Telescope (LAT), particularly those obtained with the Low Energy (LLE) technique (30 - 100 MeV), we analyze a sample of 70 GRBs to investigate the relationship between spectral lags and high-energy emission properties. Lags within the GBM energy range (10 keV – 1 MeV) are predominantly positive (76%), namely lower-energy photons arrive later than higher-energy ones as a possible consequence of a hard to soft spectral evolution. However, when comparing LLE (30–100 MeV) and GBM bands, in 37% of cases high-energy photons are delayed relative to low-energy ones. These negative lags can be interpreted as due to an additional spectral component rising in the LLE energy range as supported by the spectral analysis of these events.

Primary authors

Ms Claudia Maraventano (Università di Palermo) Giancarlo Ghirlanda (Istituto Nazionale di Astrofisica (INAF)) Lara Nava (Istituto Nazionale di Astrofisica (INAF)) Prof. Tiziana Di Salvo (University of Palermo) Wladimiro Leone (Istituto Nazionale di Astrofisica (INAF)) Rosario Iaria (Università di Palermo) Luciano Burderi (University of Cagliari) Anastasia Tsvetkova (Istituto Nazionale di Astrofisica (INAF))

Presentation materials