Gamma-Ray Polarimetry

Bernard, D.; Chattopadhyay, Tanmoy; Kislat, Fabian; Produit, N.

doi:10.1007/978-981-16-4544-0_52-1

Cited by 1 publication

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“…In the CZTI, polarization is estimated from the azimuthal scattering angle distribution (ASAD) of the Compton scattered photons (see Lei et al 1997;Chattopadhyay 2021;Bernard et al 2022 for the Compton scattering technique details). The CZTI consists of a large pixelated detector plane (geometric area of 976 cm 2 ) with pixel size of 2.5 mm × 2.5 mm and 5 mm thickness, and possesses considerable Compton scattering efficiency above 100 keV, making it suitable for Compton scattering polarimetry in 100-380 keV.…”

Section: Appendix B X-ray Polarimetry With Czt-imagermentioning

confidence: 99%

High Hard X-Ray Polarization in Cygnus X-1 Confined to the Intermediate Hard State: Evidence for a Variable Jet Component

Chattopadhyay,

Kumar,

Rao

et al. 2023

ApJL

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Cygnus X-1, the well-known accreting black hole system, exhibits several observational features hinting at an intricate interplay between the accretion disk, its atmosphere known as the corona, and the putative relativistic jet. It has been extensively studied using all available observational methods, including using the newly available technique of sensitive X-ray polarimetry. X-ray polarization characteristics are distinct for coronal and jet emissions. The low X-ray polarization measured below ∼100 keV is understood as arising from the corona. In contrast, the high polarization measurements reported above ∼400 keV required a separate jet-dominated spectral component, which spectroscopy does not demonstrate conclusively. Here we report precise polarization measurements in the 100–380 keV region made during three different subclasses of spectral states of the source using the CZTI instrument onboard AstroSat. A high polarization (23% ± 4%) is found mainly in the Intermediate Hard State of the source, and the energy-resolved measurements smoothly connect the coronal and the jet regimes. When high polarization is observed, the simultaneous spectral data hints at a separate power-law component above 100 keV. We examine the possible sources of this energy-dependent high polarization in Cygnus X-1.

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Section: Appendix B X-ray Polarimetry With Czt-imagermentioning

confidence: 99%