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Hard X-ray polarimetry—an overview of the method, science drivers, and recent findings

Chattopadhyay, Tanmoy

The last decade has seen a leapfrog in the interest of X-ray polarimetry with a number of new polarization measurements in hard X-rays from AstroSat, POLAR, GAP, and PoGO+. The measurements provide some interesting insights into various astrophysical phenomena such as coronal geometry and disk–jet connection in black hole X-ray binaries, hard X-ra…

Exploring sub-MeV sensitivity of AstroSat–CZTI for ON-axis bright sources

Rao, A. R.; Bhalerao, Varun; Mithun, N. P. S. +5 more

The Cadmium–Zinc–Telluride Imager (CZTI) onboard AstroSat is designed for hard X-ray imaging and spectroscopy in the energy range of 20–100 keV. The CZT detectors are of 5-mm thickness and hence have good efficiency for Compton interactions beyond 100 keV. The polarisation analysis using CZTI relies on such Compton events and have been verified ex…

On the unified view of extragalactic sources based on their broadband emission properties

Iyida, E. U.; Eya, I. O.; Odo, F. C.

Our understanding of the unification of jetted active galactic nuclei (AGNs) has advanced greatly as the size of extragalactic sources increased. In this paper, based on the large sample of radio sources, we compiled 680 blazars (279 flat spectrum radio quasars (FSRQs) and 401 BL Lacertae (BL Lacs)) from the 3FGL sample and 64 Seyfert galaxies (3 …

Characterisation of cosmic ray induced noise events in AstroSat-CZT imager

Rao, A. R.; Ratheesh, A.; Mithun, N. P. S. +6 more

The Cadmium Zinc Telluride (CZT) Imager onboard AstroSat consists of pixelated CZT detectors, which are sensitive to hard X-rays above 20 keV. The individual pixels are triggered by ionising events occurring in them, and the detectors operate in a self-triggered mode, recording each event separately with information about its time of incidence, de…