Search Publications
Gamma-ray spectroscopy of positron annihilation in the Milky Way
Diehl, Roland; Greiner, Jochen; Siegert, Thomas +5 more
Context. The annihilation of positrons in the Galaxy's interstellar medium produces characteristic gamma-rays with a line at 511 keV. This gamma-ray emission has been observed with the spectrometer SPI on ESA's INTEGRAL observatory, confirming a puzzling morphology with bright emission from an extended bulge-like region, while emission from the di…
Gamma rays detected from Cygnus X-1 with likely jet origin
Aharonian, F.; Blanch, O.; de Oña Wilhelmi, E. +4 more
Aims: We probe the high-energy (>60 MeV) emission from the black hole X-ray binary system, Cygnus X-1, and investigate its origin.
Methods: We analyzed 7.5 yr of data by Fermi-LAT with the latest Pass 8 software version.
Results: We report the detection of a signal at 8σ statistical significance that is spatially coincident with …
Search for 511 keV emission in satellite galaxies of the Milky Way with INTEGRAL/SPI
Vincent, Aaron C.; Diehl, Roland; Siegert, Thomas +3 more
Context. The positron (e+) annihilation γ-ray signal in the Milky Way (MW) shows a puzzling morphology: a very bright bulge and a very low surface-brightness disk. A coherent explanation of the e+ origin, propagation through the Galaxy and subsequent annihilation in the interstellar medium has not yet been found. Tentative ex…
Gamma-ray emission from SN2014J near maximum optical light
Sunyaev, R.; Churazov, E.; Hernanz, M. +17 more
Context. The optical light curve of Type Ia supernovae (SNIa) is powered by thermalized gamma-rays produced by the decay of 56Ni and 56Co, the main radioactive isotopes synthesized by the thermonuclear explosion of a C/O white dwarf.
Aims: Gamma-rays escaping the ejecta can be used as a diagnostic tool for studying the c…
GK Persei and EX Hydrae: Intermediate polars with small magnetospheres
Werner, K.; Ducci, L.; Doroshenko, V. +2 more
Observed hard X-ray spectra of intermediate polars are determined mainly by the accretion flow velocity at the white dwarf surface, which is normally close to the free-fall velocity. This allows us to estimate the white dwarf masses as the white dwarf mass-radius relation M - R and the expected free-fall velocities at the surface are well known. T…
Revealing the broad iron Kα line in Cygnus X-1 through simultaneous XMM-Newton, RXTE, and INTEGRAL observations
Grinberg, Victoria; Pottschmidt, Katja; Staubert, Rüdiger +15 more
We report on the analysis of the broad Fe Kα line feature of Cyg X-1 in the spectra of four simultaneous hard intermediate state observations made with the X-ray Multiple Mirror mission (XMM-Newton), the Rossi X-ray Timing Explorer (RXTE), and the International Gamma-Ray Astrophysics Laboratory (INTEGRAL). The high quality of the XMM-Newton data t…
Study of the reflection spectrum of the LMXB 4U 1702-429
Sanna, A.; Papitto, A.; Di Salvo, T. +7 more
Context. The source
Continued decay in the cyclotron line energy in Hercules X-1
Harrison, F. A.; Klochkov, D.; Wilms, J. +2 more
The centroid energy Ecyc of the cyclotron line in the spectrum of the binary X-ray pulsar
The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars
Buson, S.; Gehrels, N.; Dauser, T. +32 more
Context. Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics.
Aims: We study the spectral evolution between quiescent and flaring periods of 22 radio-loud AGN through multiepoch, quasi-simultaneous broadband spectra. For many of these sources these ar…
The origin of seed photons for Comptonization in the black hole binary Swift J1753.5-0127
Tsygankov, S.; Neustroev, V.; Veledina, A. +1 more
Aims: The black hole binary Swift J1753.5-0127 is providing a unique data set to study accretion flows. Various investigations of this system and of other black holes have not, however, led to an agreement on the accretion flow geometry or on the seed photon source for Comptonization during different stages of X-ray outbursts. We place constr…