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      https://www.ias.ac.in/article/fulltext/joaa/042/0082

    • Keywords

       

      AstroSat; CZT imager; sub-MeV spectroscopy; gamma ray burst.

    • Abstract

       

      Cadmium–Zinc–Telluride Imager (CZTI) onboard AstroSat has been a prolific Gamma-Ray Burst (GRB) monitor. While the 2-pixel Compton scattered events (100–300 keV) are used to extract sensitive spectroscopic information, the inclusion of the low-gain pixels ($\sim$20% of the detector plane) aftercareful calibration extends the energy range of Compton energy spectra to 600 keV. The new feature also allows single-pixel spectroscopy of the GRBs to the sub-MeV range which is otherwise limited to 150 keV. We also introduced a new noise rejection algorithm in the analysis (‘Compton noise’). These new additionsnot only enhances the spectroscopic sensitivity of CZTI, but the sub-MeV spectroscopy will also allow proper characterization of the GRBs not detected by Fermi. This article describes the methodology of single, Compton event and veto spectroscopy in 100–900 keV combined for the GRBs detected in the first year of operation. CZTI in last five years has detected $\sim$20 bright GRBs. The new methodologies, when applied on the spectral analysis for this large sample of GRBs, has the potential to improve the results significantly and help in better understanding the prompt emission mechanism.

    • Author Affiliations

       

      TANMOY CHATTOPADHYAY1 SOUMYA GUPTA2 VIDUSHI SHARMA2 3 SHABNAM IYYANI2 AJAY RATHEESH4 5 6 N. P. S. MITHUN7 E. AARTHY7 SOURAV PALIT8 ABHAY KUMAR7 SANTOSH V. VADAWALE7 A. R. RAO2 9 VARUN BHALERAO1 DIPANKAR BHATTACHARYA2

      1. Kavli Institute of Astrophysics and Cosmology, 452 Lomita Mall, Stanford, CA 94305, USA.
      2. The Inter-University Centre for Astronomy and Astrophysics, Pune 411 007, India.
      3. Department of Physics, KTH Royal Institute of Technology, AlbaNova, 10691 Stockholm, Sweden.
      4. Dipartimento di Fisica, Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy.
      5. INAF Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere, 00133 Roma, RM, Italy.
      6. Dipartimento di Fisica, Universita La Sapienza, 00185P. le A. Moro 2, Roma, Italy.
      7. Physical Research Laboratory, Ahmedabad 380 009, India.
      8. Indian Institute of Technology Bombay, Mumbai 400 076, India.
      9. Tata Institute of Fundamental Research, Mumbai 400 005, India.
    • Dates

       
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