Observations of Cygnus X-1 in the MeV band by the INTEGRAL imager

Abstract

The spectrum of the MeV tail detected in the black-hole candidate Cygnus X-1 remains controversial as it appeared much harder when observed with the INTEGRAL Imager IBIS than with the INTEGRAL spectrometer SPI or CGRO. We present an independent analysis of the spectra of Cygnus X-1 observed by IBIS in the hard and soft states. We developed a new analysis software for the PICsIT detector layer and for the Compton mode data of the IBIS instrument and calibrated the idiosyncrasies of the PICsIT front-end electronics. The spectra of Cygnus X-1 obtained for the hard and soft states with the INTEGRAL imager IBIS are compatible with those obtained with the INTEGRAL spectrometer SPI, with CGRO, and with the models that attribute the MeV hard tail either to hybrid thermal/non-thermal Comptonisation or to synchrotron emission.

6 pages, 7 figures

References in corpus (1)

• Compton telescope with coded aperture mask: Imaging with the INTEGRAL/IBIS Compton mode

Cited by in corpus (7)

• Advances in Understanding High-Mass X-ray Binaries with INTEGRAL and Future Directions
• A new lepto-hadronic model applied to the first simultaneous multiwavelength data set for Cygnus X--1
• The INTEGRAL view on Black Hole X-ray Binaries
• Hybrid Comptonization and Electron-Positron Pair Production in the Black-Hole X-Ray Binary MAXI J1820+070
• Potential origin of the state-dependent high-energy tail in the black hole microquasar Cygnus X-1 as seen with INTEGRAL
• NuSTAR spectral analysis beyond 79 keV with stray light
• e-ASTROGAM mission: a major step forward for gamma-ray polarimetry