Abstract Details
| Name: Aarthy E Affiliation: Junior Research Fellow Conference ID: ASI2017_1281 Title : GRB Polarization using AstroSat CZTI Authors and Co-Authors : T. Chattopadhyay (PRL, Penn State University), S. V. Vadawale (PRL), N. P. S. Mithun (PRL), A. R. Rao (TIFR), D. Bhattacharya (IUCAA), V. B. Bhalerao (IUCAA), S. Mate (IUCAA), A. M. Vibute (IUCAA), S. Sreekumar (VSSC) Abstract Type : Oral Abstract Category : Extragalactic astronomy Abstract : Cadmium Zinc Telluride Imager (CZTI), one of the five instruments onboard AstroSat is primarily meant for simultaneous spectroscopy and imaging in the energy range 20 keV to 200 keV. The increasing transparency of the collimators and other supporting structures of CZTI at energies beyond 100 keV provides a unique opportunity to detect GRBs during their prompt emission. At the same energy range CZTI is shown to work as a sensitive Compton Polarimeter [Chattopadhyay et al, 2014, EXPA, Vadawale et al 2015, A&A] primarily due to the pixilation nature of the detectors and significant Compton scattering probability at energies beyond 100 keV. Given the fact that GRB prompt emission is highly polarized as corroborated by recent findings by GAP and INTEGRAL, they are one of the suitable polarimetry targets for CZTI. We have analysed all the GRBs detected by CZTI over duration of one year. Around 47 GRBs were detected by CZTI from September 2015 to September 2016 and we obtained significant detection of polarization for 11 GRBs. A detailed Geant 4 simulation of AstroSat mass model including all the instruments onboard and the satellite structure was developed for polarization analysis. We would present the preliminary polarization results of the GRBs. Statistical analysis of a large sample of GRB polarization from CZTI would lead to a better understanding of the emission mechanism of GRBs. Some of these aspects along with the prospects of CZTI in constraining the emission mechanisms for GRB prompt emission would be briefly discussed here. |