Search Publications
The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
Gilli, R.; Comastri, A.; Hasinger, G.
We present a detailed and self-consistent modeling of the cosmic X-ray background (XRB) based on the most up-to-date X-ray luminosity functions (XLF) and evolution of Active Galactic Nuclei (AGN). The large body of observational results collected by soft (0.5-2 keV) and hard (2-10 keV) X-ray surveys are used to constrain at best the properties of …
INTEGRAL observations of the cosmic X-ray background in the 5-100 keV range via occultation by the Earth
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +32 more
Aims: We study the spectrum of the cosmic X-ray background (CXB) in energy range ~5-100 keV.
Methods: Early in 2006 the INTEGRAL observatory performed a series of four 30 ks observations with the Earth disk crossing the field of view of the instruments. The modulation of the aperture flux due to occultation of extragalactic objects by the Eart…
INTEGRAL/IBIS all-sky survey in hard X-rays
Sunyaev, R.; Krivonos, R.; Revnivtsev, M. +3 more
We present results of an all-sky hard X-ray survey based on almost four years of observations with the IBIS telescope onboard the INTEGRAL observatory. The dead time-corrected exposure of the survey is ~33 Ms. Approximately 12% and 80% of the sky has been covered to limiting fluxes lower than 1 and 5 mCrab, respectively. Our catalog of detected so…
Probing clumpy stellar winds with a neutron star
Walter, R.; Zurita Heras, J.
Context: INTEGRAL, the European Space Agency's γ-ray observatory, tripled the number of super-giant high-mass X-ray binaries (sgHMXB) known in the Galaxy by revealing absorbed and fast transient (SFXT) systems.
Aims: In these sources, quantitative constraints on the wind clumping of the massive stars could be obtained from the study of the har…
Six new candidate ultracompact X-ray binaries
in't Zand, J. J. M.; Jonker, P. G.; Markwardt, C. B.
Ultracompact X-ray binaries (UCXBs) appear able to sustain accretion onto the compact accretor at rates lower than in wider X-ray binaries. This may be understood by the smaller accretion disks in UCXBs: a lower X-ray luminosity suffices to keep a disk completely ionized through irradiation and, thus, keep the viscosity at a sufficiently high leve…
Polarisation studies of the prompt gamma-ray emission from GRB 041219a using the spectrometer aboard INTEGRAL
McGlynn, S.; McBreen, S.; Foley, S. +6 more
Context: Linear polarisation in gamma-ray burst prompt emission is an important diagnostic with the potential to significantly constrain models. The spectrometer aboard INTEGRAL, SPI, has the capability to detect the signature of polarised emission from a bright γ-ray source. GRB 041219a is the most intense burst localised by INTEGRAL with a fluen…
Discovery of a flux-related change of the cyclotron line energy in Hercules X-1
Klochkov, D.; Wilms, J.; Staubert, R. +5 more
Aims: We present the results of ten years of repeated measurements of the Cyclotron Resonance Scattering Feature (CRSF) in the spectrum of the binary X-ray pulsar
Hard X-ray luminosity function and absorption distribution of nearby AGN: INTEGRAL all-sky survey
Sunyaev, R.; Krivonos, R.; Revnivtsev, M. +2 more
Aims:We study the hard X-ray luminosity function and absorption distribution of local (z≲ 0.1) active galactic nuclei (AGN) and discuss the implications for AGN cosmological evolution and for the cosmic X-ray background (CXB).
Methods: We use the INTEGRAL all-sky hard X-ray survey to perform a statistical study of a representative sample of ne…
An alternative hypothesis for the outburst mechanism in supergiant fast X-ray transients: the case of IGR J11215-5952
Götz, D.; Mereghetti, S.; Sidoli, L. +4 more
Context: The physical mechanism responsible for the short outbursts in a recently recognised class of high mass X-ray binaries, the supergiant fast X-ray transients (SFXTs), is still unknown. Two main hypotheses have been proposed to date: the sudden accretion by the compact object of small ejections originating in a clumpy wind from the supergian…
A model for cyclotron resonance scattering features
Santangelo, A.; Wilms, J.; Kretschmar, P. +5 more
Aims:We study the physics of cyclotron line formation in the high-energy spectra of accreting X-ray pulsars. In particular, we link numerical predictions for the line profiles to results from observational data analysis. Therefore, first we investigate the theoretical predictions and the significance of our model parameters, and second we aim at t…