TY - JOUR
T1 - Exploring multi-pulse GRB prompt emission via novel pulse shape model
AU - Gowri, A.
AU - Pe'er, Asaf
AU - Ryde, Felix
AU - Dereli-Bégué, Hüsne
N1 - Publisher Copyright: © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
PY - 2024/7/30
Y1 - 2024/7/30
N2 - The light curves of the prompt phase of gamma-ray bursts (GRBs) exhibit erratic and diverse behaviour, often with multiple pulses. The temporal shape of individual pulses is often modelled as ‘fast rise exponential decay’ (FRED). Here, we propose a novel fitting function to measure pulse asymmetry. We perform a time-resolved spectrum analysis on a sample of 75 pulses from twenty-seven GRBs that the Fermi Gamma-ray Burst Monitor has identified. When multi-pulse bursts are taken into account, a distinct behaviour becomes evident: the first pulses have the most symmetric-like lightcurve, while subsequent pulses show an increase in the asymmetry parameter, leading to a more FRED-like form. Furthermore, we correlate pulse temporal and spectral shapes after fitting the spectra with the classical “Band" function. A moderate positive Spearman correlation between pulse asymmetry and the low-energy spectral index αmax (where the maximum is taken over all time bins that cover the pulse shape) is identified. An overlapping emission mechanism is indicated by the fact that ∼ 64% of the GRB pulses fall within the limits of the slow-cooling synchrotron and non-dissipative photospheric emission models. Thus, our findings offer a compelling hint towards understanding the origin of GRB pulses.
AB - The light curves of the prompt phase of gamma-ray bursts (GRBs) exhibit erratic and diverse behaviour, often with multiple pulses. The temporal shape of individual pulses is often modelled as ‘fast rise exponential decay’ (FRED). Here, we propose a novel fitting function to measure pulse asymmetry. We perform a time-resolved spectrum analysis on a sample of 75 pulses from twenty-seven GRBs that the Fermi Gamma-ray Burst Monitor has identified. When multi-pulse bursts are taken into account, a distinct behaviour becomes evident: the first pulses have the most symmetric-like lightcurve, while subsequent pulses show an increase in the asymmetry parameter, leading to a more FRED-like form. Furthermore, we correlate pulse temporal and spectral shapes after fitting the spectra with the classical “Band" function. A moderate positive Spearman correlation between pulse asymmetry and the low-energy spectral index αmax (where the maximum is taken over all time bins that cover the pulse shape) is identified. An overlapping emission mechanism is indicated by the fact that ∼ 64% of the GRB pulses fall within the limits of the slow-cooling synchrotron and non-dissipative photospheric emission models. Thus, our findings offer a compelling hint towards understanding the origin of GRB pulses.
UR - http://www.scopus.com/inward/record.url?scp=85200567895&partnerID=8YFLogxK
M3 - مقالة من مؤنمر
SN - 1824-8039
VL - 461
JO - Proceedings of Science
JF - Proceedings of Science
M1 - 054
T2 - 8th High Energy Phenomena in Relativistic Outflows, HEPRO 2023
Y2 - 23 October 2023 through 26 October 2023
ER -