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.

arXiv comment6 pages, 7 figures

References in corpus (21)

• ISGRI: the INTEGRAL Soft Gamma-Ray Imager
• Radiation mechanisms and geometry of Cygnus X-1 in the soft state
• A relativistic jet from Cygnus X-1 in the low/hard X-ray state
• The Mass of the Black Hole in Cygnus X-1
• Radiative Processes, Spectral States and Variability of Black-Hole Binaries
• The INTEGRAL/IBIS Scientific Data Analysis
• Polarized Gamma-ray Emission from the Galactic Black Hole Cygnus X-1
• The Soft Gamma-Ray Spectral Variability of Cygnus X-1
• Understanding the long-term spectral variability of Cygnus X-1 with BATSE and ASM observations
• Separation of two contributions to the high energy emission of Cygnus X-1: Polarization measurements with INTEGRAL SPI
• Long term variability of Cygnus X-1 V. State definitions with all sky monitors
• The High Energy Emission of the Crab Nebula from 20 keV to 6 MeV with INTEGRAL
• High-energy gamma-ray emission from Cyg X-1 measured by Fermi and its theoretical implications
• The MeV spectral tail in Cyg X-1 and optically-thin emission of jets
• IBIS/PICsIT in-flight performances
• The magnetic field in the X-ray corona of Cygnus X-1
• Jet models for black-hole binaries in the hard spectral state
• Gamma-ray observations of Cygnus X-1 above 100 MeV in the hard and soft states
• X-ray variability patterns and radio/X-ray correlations in Cyg X-1
• Compton telescope with coded aperture mask: Imaging with the INTEGRAL/IBIS Compton mode
• The structure of the jet in Cyg X-1 inferred from orbital modulation of the radio emission

Cited by in corpus (8)

• Advances in Understanding High-Mass X-ray Binaries with INTEGRAL and Future Directions
• High-energy gamma-rays from Cyg X-1
• 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