| Name: | Rushikesh Sonawane |
| Affiliation: | Indian Institute of Science Education and Research, Thiruvananthapuram |
| Conference ID : | ASI2024_516 |
| Title : | Spectro-Polarimetry of GRB180427A prompt emission: Evidence for two different emission sites. |
| Authors : | Rushikesh Sonawane1, Shabnam Iyyani1, Soumya Gupta2, and Tanmoy Chattopadhyay3 |
| Authors Affiliation: | 1 Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, 695551, India
2 Homi Bhabha National Institute, Anushakti Nagar, Mumbai Maharashtra-400094, India
3 Kavli Institute of Particle Astrophysics and Cosmology, Stanford University 452 Lomita Mall, Stanford, CA 94305, USA |
| Mode of Presentation: | Poster |
| Abstract Category : | High Energy Phenomena, Fundamental Physics and Astronomy |
| Abstract : | Gamma-ray bursts are the brightest explosions in the cosmos that happens during the death of massive stars or merger of compact objects such as binary neutron stars or a neutron star - black
hole. However, the dynamics of the origin of
these gamma-ray emissions during the event are still largely a mystery. From the joint observations of GRB 180427A by Fermi Gamma ray
space telescope and Cadmium Zinc Telluride Imager onboard AstroSat, we find conclusive evidence for gamma-ray
emissions originating from two different sites with two different polarisation properties. Consequently, the time-resolved polarisation
analysis reveals that the polarisation angle (PA) as well as the polarisation fraction (PF) evolves in
accordance to the temporal evolution of the two emission pulses which peaks with a time delay of 5+/-2 s. It is observed that the first emission pulse exhibits a spectral profile
consistent with a blackbody, while the second pulse's spectrum is consistent with a power law
with an exponential cutoff. These emissions display polarisations exceeding 22% for the
first pulse and 79% for the second pulse, with corresponding polarization angles (PA) of
-29.35 ^{+44.80}_{-10.27} deg and 32.48 ^{+6.90}_{ -36.05}deg in the detector plane respectively, at a 95% confidence level for one parameter of interest.
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