Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: Synchrotron Origin?

• Published in: arXiv.org 2022-01
• Main Authors: Gupta, Rahul, Gupta, S, Chattopadhyay, T, Lipunov, V, Castro-Tirado, A J, Bhattacharya, D, Pandey, S B, Oates, S R, Kumar, Amit, Y -D Hu, Valeev, A F, P Yu Minaev, Kumar, H, Vinko, J, Dimple, Sharma, V, Aryan, A, Castellón, A, Gabovich, A, Moskvitin, A, Ordasi, A, Pál, A, Pozanenko, A, B -B Zhang, Kumar, B, Svinkin, D, Saraogi, D, Vlasenko, D, Fernández-García, E, Gorbovskoy, E, Anupama, G C, Misra, K, Sárneczky, K, Kriskovics, L, Castro-Tirado, M Á, Caballero-García, M D, Tiurina, N, Balanutsa, P, Lopez, R R, Sánchez-Ramírez, R, Szakáts, R, Belkin, S, Guziy, S, Iyyani, S, Tiwari, S N, Vadawale, Santosh V, Sun, T, Bhalerao, V, Kornilov, V, Sokolov, V V
• Format: Article
• Language: English
• Subjects: Broadband; Cadmium zinc tellurides; Emission analysis; Gamma rays; Kinetic energy; Polarization; Red shift; Spectra; Synchrotrons; Telescopes; Time measurement; Zinc telluride; Zinc tellurides
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2201.01167

Multi-pulsed GRB 190530A, detected by the GBM and LAT onboard \fermi, is the sixth most fluent GBM burst detected so far. This paper presents the timing, spectral, and polarimetric analysis of the prompt emission observed using \AstroSat and \fermi to provide insight into the prompt emission radiation mechanisms. The time-integrated spectrum shows conclusive proof of two breaks due to peak energy and a second lower energy break. Time-integrated (55.43 \(\pm\) 21.30 \%) as well as time-resolved polarization measurements, made by the Cadmium Zinc Telluride Imager (CZTI) onboard \AstroSat, show a hint of high degree of polarization. The presence of a hint of high degree of polarization and the values of low energy spectral index (\(\alpha_{\rm pt}\)) do not run over the synchrotron limit for the first two pulses, supporting the synchrotron origin in an ordered magnetic field. However, during the third pulse, \(\alpha_{\rm pt}\) exceeds the synchrotron line of death in few bins, and a thermal signature along with the synchrotron component in the time-resolved spectra is observed. Furthermore, we also report the earliest optical observations constraining afterglow polarization using the MASTER (P \(